ABSTRACTS 1969 PARTICLE ACCELERATOR CONFERENCE ACCELERATOR ENGINEERING AND TECHNOLOGY March 5-7, 1969 Shoreham Hotel Washington, D.C. Sponsored by American Physical Society Institute of Electrical and Electronics Engineers Nuclear Science Group National Bureau of Standards, Center for Radiation Research National Science Foundation U.S. Atomic Energy Commission FOREWORD This book of abstracts has been prepared for the convenience of the Conference participants. The papers are listed in the order that they will appear in the Conference Proceedings. The papers that will be presented orally are indicated in the index by a dagger. Time limitations will permit the presentation of only a relatively few of the many excellent papers accepted by the Program Committee. Papers for oral presentation were chosen to depict the present and emerging state-of-the-art and to achieve a well-balanced program. In the Proceedings no distinction will be made between papers which were presented and those which were not. These abstracts are also being published in the Bulletin of the American Physical Society and the IEEE Spectrum . The Conference Proceedings, to be published as an issue of IEEE Transactions on Nuclear Science , will be mailed to Conference participants this summer. Complimentary copies will not be sent to all authors as in the past. Order forms for additional copies will be available at the registration desk. The cost of publishing the Proceedings will be partially borne by the National Science Foundation and the United States Atomic Energy Commission. U. S. DEPARTMENT OF COMMERCE National Bureau of Standards Washington, D. C. PROGRAM Wednesday, March 5, 1969 9:30 A.M. - Regency Room Opening Remarks - J. A. Martin, Oak Ridge National Laboratory, Conference Chairman Welcome - Carl O. Muehlhause, Director, Center for Radiation Research, National Bureau of Standards 9:45 A.M. - Session A - Regency Room Plenary Session I Chairman: G. K. Green, Brookhaven National Laboratory 2:00 P.M. - Session B - Palladian Room Ion Sources, High Voltage Equipment, DC Accelerators and Operating Machines Chairman: R. G. Herb, University of Wisconsin 2:00 P.M. - Session C - Diplomat Room Beam Dynamics Chairman: E. D. Courant, National Accelerator Laboratory Thursday, March 6, 1969 9:00 A.M. - Session D - Diplomat Room Linear Accelerators Chairman: L. Rosen, Los Alamos Scientific Laboratory 9:00 A.M. - Session E - Palladian Room Cyclotrons Chairman: M. S. Livingston, National Accelerator Laboratory 2:00 P.M. - Session F - Diplomat Room Radiofrequency Systems, Safety, Radiation and Remote Handling Chairman: P. R. Tunnicliffe, Chalk River Nuclear Laboratories 2:00 P.M. - Session G - Palladian Room Magnets (including Superconducting), Power Supplies, Round Table Discussion on Heavy Ion Accelerators Chairman: G. R. Lambertson, Lawrence Radiation Laboratories 6:00 P.M. - Cocktails - Regency Room The hotel will make bar service available. 7:30 P.M. - Dinner Session - Regency Room Speaker: The Honorable Craig Hosmer, Congressman from California, member of the Joint Committee on Atomic Energy Friday, March 7, 1969 9:00 A.M. - Session H - Diplomat Room Computer Uses, Instrumentation, Controls and Vacuum Systems Chairman: B. B. Cork, Argonne National Laboratory 9:00 A.M. - Session I - Palladian Room Round Table Discussion on Booster Injectors, New Accelerator Ideas, Superconducting Accelerators Chairman: E. J. Lofgren, Lawrence Radiation Laboratory 2:00 P.M. - Session J - Regency Room Plenary Session II Chairman: R. S. Livingston, Oak Ridge National Laboratory Session A - Plenary I Al Invited Paper. Accelerators and the World Around Us , Denis M. Robinson, High Voltage Engineering Corp . A2 Invited Paper. Serpukhov 70-GeV Proton Synchrotron Start-Up and Adjustment, A. A. Naumov, Institute of High Energy Physics, Serpukhov, USSR. A3 Invited Paper. The 200-GeV Accelerator , T. L. Collins, National Accel- erator Laboratory. Ak Invited Paper. Collective Method of Proton Acceleration , V. P. Sarant- sev, Joint Institute for Nuclear Research, Dubna. A 5 Invited Paper. The Electron-Ring Accelerator , D. Keefe, Lawrence Radi- ation Laboratory. Session B - Ion Sources, High Voltage Equipment, DC Accelerators, and Operating Machines Bl Invited Paper. Some Considerations Associated with Accelerator Ion Sources , Th. J. M. Sluyters, BNL " ~ B2t A Mass Analyzer System for the High Voltage Terminal of a Van de Graaff Heavy-Ion Accelerator , F . G . Ruedenaur , MIT B3t An Ion Source for Negative Heavy Ions , M. Mueller and G. Hortig, Max- Planck- Institute, Heidelberg Bk Ion Source Modification for He~ Ions , G. F. Wells and J. W. Johnson, ORNL B5 Inert Gas Ion Beams from a Duoplasmatron Ion Source , N. Wells and P. R. Hanley, Radiation Dynamics B6 High Current, Continuous Duoplasmatron Ion Source , John H. Ormrod, AECL, Chalk River B7 Test of LASL Ion Source with 200-kV Pierce Accelerating Column , C. R. Emigh, E. A. Meyer and D. W. Mueller, LASL B8 The "HIPAC" as a Source of Highly Stripped Heavy Ions , J. D. Daugherty, J. E. Eninger, C. S. Janes and R. H. Levy, Avco Everett Research Labora- tory B9 Current Status of the "HIPAC " Source of Highly Stripped Heavy Ions , J. D. Daugherty, J. E. Eninger, G. S. Janes and R. H. Levy, Avco Everett Research Laboratory BlOt Design and Performance of the Sandia Laboratories Hermes II Flash X-ray Generator , Thomas Hugh Martin, Sandia Laboratories tPresented orally. Bll Development of a 18 -Megavolt Marx Generator , D. L. Johnson, T. H. Martin and K. R. Prestwich, Sandia Laboratories, Albuquerque B12 Dynamics of Electron Beam Flow from Pulsed, High Current "Field Emission ", Cathodes , W. R. McNeil and J. R. Uglum, Ion Physics Corporation B13t A Monte -Carlo Model for the Heavy-Ion Charge Change Accelerator , G. Hor- tig, Max-Planck-Institute, Heidelberg BlU The Ion Optic System for the Heavy-Ion Charge Change Accelerator , M. Schechter, G. Hortig and H. Spillecke, Max-Planck-Institute, Heidelberg B15- Invited Paper. Tandem Accelerators , H. E. Wegner, BNL Bl6t The Tandem Dynamitron , P. R. Hanley, M. R. Cleland, C. F. Mason, K. H. Morgans tern and C. C. Thompson, Radiation Dynamics B17 Suppression of Vertical "Jitter" of the Beam from an Inclined Field Tube 3-Stage FN-Type Tandem Van de Graaff Accelerator , Nancy J. Caling, Harold Fauska and Fred H. Schmidt, University of Washington Bl8 Magnetically Suppressed Tubes for Electrostatic Accelerators , F • A . Howe , AERE, Aldermaston, England B19 A Study of Vacuum Requirements for the Acceleration of Heavy Ions in an MP Tandem Van de Graaff , F. Chmara, G. Ryding and J. Shaw, High Voltage Engineering Corp. B20 Wide -Range Van de Graaff Pulser , E. J. Rogers, BNL B21 Selection of a Vac -Ion Pump for a Terminal Ion Source , J. A. Benjamin, BNL B22 A High Speed Gas -Handling System for the Brookhaven National Labora - tory Three-Stage Tandem Van de Graaff Facility , K. F. Minati, Brook- haven National Laboratory B23 High Voltage Insulators for Particle Accelerators , K. D. Srivastava, University of Waterloo, Canada B2^4 Acceleration of Intense Positive Ion Beams at Megavolt Potentials , M. R. Cleland, P. R. Hanley and C. C. Thompson, Radiation Dynamics B25 High Voltage DC Power Supplies for Beam Injectors , Glint er Reinhold, Emile Haefely & Co., Switzerland B26 Pressurized 1-MeV Electron Accelerator of the Twin-Tank Design for Electron Microscopy , Glinter Reinhold, Emile Haefely & Co., Switzerland B27 Design Equations for Dynamitron Type Power Supplies in the Megavolt Range , C. C. Thompson and M. R. Cleland, Radiation Dynamics B28 Performance and Modifications of a 200-keV Heavy Ion Accelerator Facil - ity, Roman Laubert and Richard K. Robinson, New York University B29 The Injector Complex for the LAMPF Accelerator , P. W. Allison, C. R. Emigh and R. R. Stevens, Jr., LASL B30 A Polarized Ion Source for the Berkeley 88 -Inch Cyclotron , A. Luccio, D. J. Clark, D. Elo, P. Frazier, D. Morris and M. Renkas , LRL B31 Production and Acceleration of Deuterium and Helium Ions , A. Passner, T. Bertuccio, M. Isaila, D. Sober and K. Vosburgh, Princeton-Pennsylvania Accelerator B32 Some Results of Studies of Proton Beam Production and Transport for PLANIM , T. R. Walsh, et al., Rutherford Laboratory, England B33 Post Acceleration Beam Pulse Length Chopper , R. J. Averill and T. L. Collins, Cambridge Electron Accelerator, Harvard University B3^+ Operation of a h-mk Dynamitron as a Monoenergetic Neutron Source , P. R. Hanley, Radiation Dynamics; A. W. Haberl and A. Taylor, Cornell University B35 Performance of the Cornell 10-CeV Electron Synchrotron , M. Tigner, Cornell University B36t Operation and Performance of the UW Physical Sciences Laboratory Electron Storage Ring , E. M. Rowe , R. A. Otte, C. H. Pruett and J. D. Steben, University of Wisconsin B37t A ccelerator Development Activity of the Radiotechnical Institute, USSR Academy of Sciences, A. L. Mints, Radiotechnical Institute of the USSR Academy of Sciences, Moscow B38 Simultaneous Multiple Targeting Techniques , L. G. Ratner, F. Hornstra, S. Marcowitz, T. Romanowski, R. Scherr, ANL; N. Reay, Ohio State University B39 Bevatron External Proton Beam Facilities , T. Elioff, R. J. Force, W. D. Hart sough and K. H. Lou, LRL B^O Design and Construction of Physical Facilities, AGS Conversion Project , J. H. Lancaster, BNL Session C - Beam Dynamics CI Invited Paper. Beam Dynamics in Circular Accelerators , L. Smith, National Accelerator Laboratory C2t Beam Amplitude Behavior upon Crossing a Linear Coupling Resonance with Damping in One Dimension , M. J. Lee and E. D. Courant, BNL; C. Pellegrini, Laboratori Nazionali di Frascati; A. M. Sessler, LRL C3 t Transverse Space-Charge Effects in Circular Accelerators , Frank J. Sach- erer, LRL CU t The Effect of Ions on the Symmetrical Throbbing Beam Mode , H. G. Here-ward, P. L. Morton, K. H. Schindl, CERN, Geneva ~ C5t Collective Effects in Accelerators , A. A. Kolomenski, Physical Insti- tute of the USSR Academy of Sciences (Lebedev), Moscow C6 Damping Bunch Shape Oscillations in the Brookhaven ACS , E . C . Raka , BNL C7 Investigations of Gradient Corrections for the ACS , J. C. Herrera and M. Month, BNL C8 Orbits and Nonlinear Effects in Terms of the Field Coefficients in the Median Plane , C. S. Chien, ANL C9 Invited Paper. Beam Dynamics in Linear Accelerators , R. L. Gluckstern, University of Massachusetts, Amherst ClOt Numerical Calculations on Transverse Emittance Growth in Bright Linac Beams , R. Chasman, BNL Cll t Interaction of a Particle Beam with Superconducting Waveguide of a Proton Accelerator , F. Heller, H. Hirschmann, C. Passow, E. Sauter, D. Schulze, H. Siefkes, Universitat Karlsruhe C12 Space-Charge Forces in a Linac Buncher , B. G. Chidley and C. E. Lee- Whiting, Atomic Energy of Canada Limited C13 Multigap Debunchers , A. Benton, BNL ClU Phase Stability Studies for the ING Linac , W. S. Chapman, Chalk River Nuclear Laboratories C15 An Analysis of Travelling -Wave Prebunchers , G. W. Petersen and W. J. Gallagher, Applied Radiation Cl6 Transverse Space-Charge Effects in Bunched Beams , J . Claus , BNL C17 Design of the Low Energy Beam Transport System of the BNL 200 MeV Injector Linac, R. Chasman and T. J. M. Sluyters, BNL Cl8 Space Charge Effects in High Current Linear Electron Accelerator Trans - port Systems , T . Khoe and G . Mavrogenes , ANL C19 Particle Trajectory Perturbations in Beam Handling Systems , J. Dobson, Gulf General Atomic; W. J. Gallagher, Applied Radiation Corporation C20 Design and Evaluation of Particle Beam Handling Systems , Annija Calejs and Philip Trent, High Voltage Engineering Corp. C21t Initial Performance of the AGS Slow External Beam , L. N. Blumberg, M. Q. Barton, G. W. Bennett, J. D. Fox, H. C. H. Hsieh, R. J. Nawrocky and A. V. Soukas, BNL C22 Extraction and Transfer of High-Quality Beams from Synchrotrons of the FOOFDOD Type, with Application to the Omnitron , Philip F . Meads , Jr . , Brobeck and Associates; Frank B. Selph, Lawrence Radiation Laboratory C23 Two-Turn Extraction from an Injector Synchrotron, A. Van Steenbergen , BNL C2U The Effect of Momentum Spread in Slow Extraction at an Integer Resonance - A Theoretical Study , P. Strolin and E. J. N. Wilson, CERN, Geneva C25 An External Beam for the Cornell 2-GeV Electron Synchrotron , A. Browman, Louis N. Hand, G. Rouse, and T. Tso, Cornell University C26t Design of the 200-GeV Slow Extracted Beam at HAL, R. Andrews, A. Maschke, R. Mob ley, and C. Rode, National Accelerator Laboratory C27 Energy-Loss Extraction System with Thin-Septum Plunged Magnet at HLMROD , A. G. A. M. Armstrong, M. J. O'Connell, R. H. C. Morgan and M. J. Shee- han, Rutherford Laboratory, England C28 Extraction from NIMROD Using the Two-Thirds Resonance , M. R. Harold, Rutherford Laboratory, England C29 Lattice of the NAL 200-GeV Proton Synchrotron , A. A. Garren, National Accelerator Laboratory C30 Lenses for High Energy Electron Beams , W. J. Gallagher, Applied Radiation Corporation C31 Design of a High Energy Medical Linear Accelerator , H. Huber and H. Le- boutet, CSF - Corbeville C32 The Application of Transient Beam Loading in Linear Accelerators to Obtain a Fixed Charge/Pulse , J. Dobs on and C. B. Williams, Gulf General Atomic Incorporated C33 Proton Beam Cooling with Electrons in the Non-Relativistic-Case , W. Maur- er, Ke rnf or s chungs zent rum Karlsruhe Session D - Linear Accelerators Dl Invited Paper. Prospects for High Duty Cycle Electron Linear Acceler - ators , J. E. Leiss, National Bureau of Standards D2t The Astron Linear Accelerator , Jack W. Beal, LRL, Livermore D3t First Operation of the High Duty Cycle Saclay Electron Linac (A.L.S.) , G. Azam and H. Leboutet, CSF, Corbeville; F. Netter and C. Tzara, CEN de Saclay DU Dynamics of the Beam of Electrons in the A.L.S. , G. Azam, A. Bensussan, H. Leboutet and G. Roux, CSF - Corbeville D5 Converter and Positron Acceleration on the A.L.S. , Mine. J. Aucouturier, H. Leboutet, G. Azam and C. Perraudin, CSF, Corbeville D6 Dutch Proposal for 10% Duty Factor, High Energy Electron Linac , C . De Vries and P. J. T. Bruinsma, Institute for Nuclear Physics Research, Amsterdam D7 The 95-MeV Electron Linac at Amsterdam , P. J. T. Bruinsma and C. De Vries, Institute for Nuclear Research, Amsterdam D8t Recent Beam Performance and Developments at SLAC , R. H. Helm, H. A. Hogg, R. F. Koontz, G. A. Loew, R. H. Miller and R. B. Neal, SLAC D9 Klystron Performance at SLAC , Jean V. Lebacqz, SLAC D10 The Development of a 30-MW, 2856-MHz Klystron for Accelerator Service , F. G. Hammer sand and J. R. Tomcavage, RCA Dllt Performance of 1^0-MeV High Current Short Pulse Linac at ORNL , N. Pering, Varian Associates; T. A. Lewis, ORNL D12 Standing Wave Operation of Electron Linear Accelerators , W. J. Gallagher, Applied Radiation Corp. D13 Velocity Modulation System for Enhancement of 50 Picosecond Radiation Pulse , N. J. Norris and R. K. Hanst, E.G. and G. Dlk Invited Paper . Resonantly Coupled Standing -Wave Accelerator Structures for Electron and Proton Linac Applications , E. A. Knapp, LASL D15 Resonant Frequencies and Mode Structures of an Alvarez Type Linac Cavity , M. J. Lee, R. Chasman, H. K. Peterson, BNL; R. L. Cluckstern, University of Massachusetts Dl6 Method for Calculating Mode Structure and Field Flatness in an Alvarez Type Linac Cavity , R. L. Cluckstern, University of Massachusetts D17 Invited Paper. Proton Linear Accelerator , G. W. Wheeler, BNL Dl8 Status of the RF System for the 200-MeV Linac Injector for the AGS , J. Keane, R. F. Lankshear, J. F. Sheehan and R. L. Witkover, BNL D19 Beam Emittance-Time Variation of the 50-MeV Proton Linear Accelerator of the Zero Gradient Synchrotron , Mohamed E. Abdelaziz, UAR Atomic Energy Establishment, Cairo D20 A Unique High Duty Factor Series Hard-Tube Modulator for Use in the Los Alamos Meson Physics Facility , J. Ross Faulkner, IASL D21 The BNL 50-MeV Linac RF Multiport System , J. T. Kean, B. DeVito and A. J. McNerney, BNL D22 Micro-wave Instrumentation for Accelerator RF Systems , R. A. Jameson, W. J. Hoffert and D. I. Morris, LASL "~ D23t Recent Improvements to the Berkeley Hilac , R. Main, J. M. Haughian, D. Vorkoeper, A. T. Watanabe, T. Henderson and E. Chuck, LRL D2^ Study on Interdigital H-Type Structure for Heavy-Ion Linear Accelerators , M. Bres, A. Chabert, J. C. Gavet, D. T. Tran, B. Veyron, G. Voisin, Institut de Physique Nucleaire, Universite de Lyon, France D25 A New Structure for Heavy Ion Linacs , J. Pottier, CEN de Saclay, France D26 Transit Time Factors and Field Magnification Factors in Ion Linac Gaps , D. 0. Boehne, University of Heidelberg, West Germany D27 RF System Development for the Heavy Ion Linac , B. Stadler, Unilac Group, University of Heidelberg, West Germany D28 Linac Cavity Technology , D. Boehne, Unilac Group, University of Heidel- berg, West Germany D29 An Inexpensive Method of Cooling an RF Cavity , R. Main and J. M. Haughian, LRL Session E - Cyclotrons El Invited Paper , General Design Features of the Indiana University 200 - MeV Cyclotron , M. E. Rickey, M. B. Sampson and B. M. Bardin, Indiana University E2 Invited Paper. Synchrocyclotron Improvement Programs , Henry G. Blosser, Michigan State University E3t Magnetic Field Tolerances for the TRIUMF 500-MeV H~ Cyclotron , M. K. Craddock and J. Reginald Richardson, University of British Columbia E^-t JINR Synchrocyclotron Modernization Design , V. P. Dmitrievsky, Joint Institute of Nuclear Research, Dubna E5t Nevis Synchrocyclotron Conversion Project , R. Cohen, E. Martin, J. Rain- water, R. Schneider and K. Ziegler, Columbia University, and S. Ohnuma, Yale University E6 Electric Focusing at the Center of a Cyclotron , R. Cohen and J. Rainwater, Columbia University E7 Nevis Synchrocyclotron Conversion Program - RF System , R. Schneider and J. Rainwater, Columbia University E8 Extraction from the Modified Nevis Synchrocyclotron , R. Cohen, E. Martin, K. Ziegler, Columbia University, and S. Ohnuma, Yale University E9 t The University of Maryland Isochronous Cyclotron , R. E. Berg, J. F. Bridges, K. D. Jenkins, H. Kim, M. Reiser and T. Zinneman, University of Maryland; T. H. Johnson, W. H. White, Raytheon Company; P. Delphin, F. Dupont, A. Dupuis , R. Jean, R. Lacaze, H. Leboutet, Compagnie Generale de T.S.F., Paris E10 Design of the Beam Transport System for the University of Maryland Cyclotron , R. E. Berg, University of Maryland Ell Magnet and Extraction Studies , P. Delphin, CSF, Paris; H. Kim and M. Reiser, University of Maryland E12 Center - Region Design and Initial Orbits in the Maryland University Isochronous Cyclotron , M. Reiser and T. Zinneman, University of Mary- land; F. Dupont and P. Delphin, CSF, Paris E13t Calculation of the Central Orbits in a Compact Isochronous Cyclotron , J. M. Van Nieuwland and N. Hazewindus, Philips Research Laboratories, Eindhoven ElU Axial Injection System for a Compact Isochronous Cyclotron , N. Haze- windus and A. Petterson, Philips Research Laboratories, Eindhoven E15 RF System for a Compact Isochronous Cyclotron , J. Geel and A. J. J. Franken, Philips Research Laboratories, Eindhoven El6t Beam Optics and Space Charge Effects in the Axial Injection Line for the 88-in. Cyclotron , F. C. Resmini and D. J. Clark, LRL E17 Design and Construction of the Axial Injection System for the 88-in . Cyclotron , D. Clark, R. Burger, A. Carneiro, D. Elo, P. Frazier, A. Luccio, D. Morris, M. Renkas , F. Resmini, LRL El8t Extraction from the Julich 90-MeV-d AEG-Isochronous Cyclotron H. Thimmel and P. Wucherer, AEG-Telefunken E19 The k MeV Separated-Orbit Cyclotron , J. A. Martin, L. N. Howell, E. D. Hudson, R. S. Livingston, J. E. Mann, S. W. Mosko, E. G. Richardson, Jr., R. E. Worsham, N. F. Ziegler, ORNL E20 Test Results from Coaxial Cavities for Separated Orbit Cyclotrons , N. F. Ziegler, ORNL E21 Unique Mechanical Fabrication Techniques on the Brookhaven National Laboratory Cyclotron , R. J. McCracken, C. P. Baker, J. Mann, J. Hes- singer, BNL E22 Improvements in the Michigan State University Cyclotron RF System , William P. Johnson, Michigan State University E23 Ion Phase Measuring Equipment of the Relativistic Isochronous Cyclotron at Julich, H. Eyber and E. Bittel, AEG-Telefunken E24- A Low Power Magnetic Channel with Dipole Compensation , T. Khoe, R. Benaroya, J. J. Livingood, W. J. Ramler, and ¥. Wesolowski, Argonne National Laboratory E25 Magnetic Extraction Channel for the 30-Inch AW 1 Cyclotron , George 0. Hendry and James L. Tom, The Cyclotron Corporation E26 Beam Loss Due to the Pr — "Qz = 1 and the 3x) r — "Qz = 3 Resonances , M. L. Mallory and J. A. Martin, Oak Ridge National Laboratory E27 Meson Channel Design for the SREL Synchrocyclotron , H. 0. Funs ten and R. T. Siegel, College of William and Mary E28 Design of Stopped Muon Channels , S. Ohnuma, Yale University Session F - Radiofrequency Systems, Safety, Radiation and Remote Handling Fl NAL Booster and Storage Ring RF Systems , J. A. Dinkel, Q. A. Kerns, L. A. Klaisner, and G. S. Tool, National Accelerator Laboratory F2 + Electronic Systems of the 70-GeV Proton Synchrotron , S.M. Rubchinsky, Radiotechnical Institute of the USSR Academy of Sciences, Moscow F3 Calculated Beam-Loading Effects in the NAL Main Ring RF System , G. Rees, National Accelerator Laboratory F4 A Dielectric -Loaded Slow Wave Structure for Separation of Relativistic Particles , Christopher T. M. Chang, John W. Dawson, and Robert L. Kustom, Argonne National Laboratory F5 Long-Pulse Radio Frequency Separator Test Facility , John W. Dawson, Alfred Moretti, and Joseph J. Peerson, Argonne National Laboratory F6 Improvement in the RF Capture by Using Nonsinusoidal Accelerating Voltages , T. Bertuccio, M. Isaila, J. Kirchgessner, F. Larsen, A. Passner, and K. Prelec, Princeton- Pennsylvania Accelerator F7 Engineering Study of Thermal Problems in Ferrites of AGS Accelerating Cavities , E. Jablonski and V. J. Buchanan, Brookhaven National Labora- tory F8 Application of the Two -Power- Supply Method to the Ferrite Bias of an RF Resonator of a Rapid-Cycling Synchrotron , Louis L. Reginato and Bob H. Smith, Lawrence Radiation Laboratory F9 Non-linear Effects in "Linear" Ferrites at High Rf Fields , G. Rakowsky, Brookhaven National Laboratory F10 Digital Measurement of Ferrite Hysteresis Loops , J. E. Katz, Lawrence Radiation Laboratory; Q,. A. Kerns and B. R. Sandberg, National Ac- celerator Laboratory Fll Simplified Design Techniques for Distributed Power Amplifiers for Synchrotron and Cyclotron Driver Applications , William L. Gagnon and Bob H. Smith, Lawrence Radiation Laboratory F12 The Electrical Breakdown of Vacuum Insulated Electrodes Under Radio Frequency Stress , Robert L. Kustom, Argonne National Laboratory F13 Numerical Design of the Shape of an Azimuthally Symmetric RF Cavity that Resonates at Given Frequencies and Has Zero Response at Other Specified Frequencies , Francis C. Younger and Philip F. Meads, Jr., Brobeck and Associates F14 Invited Paper. Safety Guidelines for Accelerator Installations , H. Paul Hernandez, Lawrence Radiation Laboratory F15 Tables for the Determination of the Lateral Shielding Requirements of High Energy Electron and Proton Accelerators , Keran 'Brien, USAEC Health and Safety Laboratory-NY F16 Radiation Studies Around Extracted Proton Beams at Nimrod , K. B. Shaw and G. R. Stevenson, Rutherford High Energy Laboratory F17 Gamma Ray Background Analysis of the NASA Langley Research Center SREL 600-MeV Proton Synchrocyclotron for the Relatively Short and Long-Li ved Gamma Rays , Emanuel Rind, NASA — Langley Research Center F18 Primary Safety Problems of Particle Accelerators , Wm. Cornelius Hall, Chemtree Laboratories F19 A Fast Protection System for Linear Accelerators , Dale T. Van Buren, Los Alamos Scientific Laboratory F20 The University of Toronto Solid-State Interlock System , E. W. Horrigan, R. Millar, and K. Schwedtmann, University of Toronto F21 New Personnel Interlock System and Procedures for the RPI Linac Lab , J. Haken, D. S. Morse, and R. M. Ryan, Rensselaer Polytechnic Institute F22 A Multichannel Radiation Monitor with Logarithmic Response from 0.1 to 1Q 6 mR/hr , T. G. Dzubay and R. E. Pollock, Princeton University F23 Remote Maintenance Concepts for the Los Alamos Meson Physics Facility , Mahlon T. Wilson, LASL F24 General- Purpose Servo-Manipulator for Remote Maintenance of Accelera - tors , C. R. Flatau, Brookhaven National Laboratory F25 Application of Remote Handling in the PS-Tunnel , M. Ellefsplass, R. A. Home, and W. Richter, CERN F26 Neutron Flux in a Labyrinth Due to a 3-GeV Proton Beam Incident on Lead , W. Schimmerling and M. Awschalom, Princeton-Pennsylvania Accelerator F27 Radiation Damage Studies of Zero Gradient Synchrotron Magnet Insulation and Related Materials , F. W. Markley, G. A. Forster, R. Booth, Argonne National Laboratory F28 Mineral -Insulated Magnets for High Radiation Environments , A. Harvey and S. A. Walker, Atomic Energy of Canada Limited and Pyrotenax of Canada Limited F29 The "Sphere Dump" — A New Low-Cost High-Power Beam Dump Concept and a Catalytic Hydrogen-Oxygen Recombiner for Radioactive Water Systems , D. R. Walz and L. R. Lucas, Stanford Linear Accelerator Center F30 Stopping a 200-MeV, 40-kW Proton Beam , G. S. Levine and W. H. Moore, Brookhaven National Laboratory F31 The Radiation Shielding and Beam Dumps for the NAL 100-GeV Proton Storage Rings , Miguel Awschalom, National Accelerator Laboratory F32 External Target Irradiation Facility for the Princeton University AVF Cyclotron , C. C. Foster, B. Greenebaum, and E. A. Phillips, Princeton University F33 Shutter and Collimator "with Rotating Radiation-Cooled Elements for the Beam from the Princeton AVF Cyclotron , C. C. Foster, Princeton University F34 Improvements in Liquid Hydrogen Target Techniques , Mitchell 0. Hoenig, Cambridge Electron Accelerator, Harvard University F35 A Liquid Hydrogen Target for SLAC 's 30-mA Electron Beam , R. Bell, H. Clay, J. Mark and W. Pierce, Stanford Linear Accelerator Center F36 Refrigerated Liquid Hydrogen Targets at the Zero Gradient Synchrotron , Richard D. Roman, Argonne National Laboratory F37 Insulated-Target Instrumentation in the AGS Slow External Beam , G. W. Bennett, Deutsche s El ektronen- Synchrotron F38 Insertion and Extraction of Internal Targetry at the Zero Gradient Synchrotron , Thaddeus D. Cassidy, Andrew J. Gorka, and Robert B. Wehrle, Argonne National Laboratory F39 Self -Optimizing Target Control System , Charles W. Potts and Donald F. Marcks, Argonne National Laboratory F4-0 A Taut Wire Alignment System with Automatic Readout of 5 of the 6 Degrees of Freedom of a System of Solid Bodies , William Davie s -White, Stanford Linear Accelerator Center F41 A Precision Goniometer for Use in Accelerators , E. A. Thebado, Cambridge Electron Accelerator F42 Low Conductivity Cooling Water Systems , George Homsy and William J. Jones, Cambridge Electron Accelerator F43 Accelerator Cooling System Design and Economics , E. Eno, W. P. Carpender, E. C. Litsinger and M. K. Lyster, Lawrence Radiation Laboratory F44 Inert Gas Purifier for SLAC 's 2-m Streamer Chamber , Per Thingstad, Stanford Linear Accelerator Center Session G - Magnets (Including Superconducting), Power Supplies, Round Table Discussion on Heavy Ion Accelerators __t Gl Some Engineering Problems of the Serpukhov Accelerator, E. G. Komar, The Research Institute of Elec trophy sic al Equipment, Leningrad , USSR G2 Design of the Main Ring Magnets for the NAL 2Q0-GeV Synchrotron , R. J. Lari, Argonne National Laboratory; L. C. Teng, National Ac- celerator Laboratory G3 Direct Powering of the 200-GeV Synchrotron Magnets From the Utility System , R. L. Cassel, National Accelerator Laboratory; J. E. Van Ness, Northwestern University G4 Static Power Supplies for Pulse Loads , J. A. Fox, Rutherford Labora- tory, England G5 Pulsing the ZGS Directly from the Utility Line , Alfred Rohrmayer and John F. Sellers, Argonne National Laboratory G6 Tolerable Limits of Voltage Fluctuations Produced by Magnets Pulsed Directly off Alternating Current Power Lines , Walter F. Praeg, Argonne National Laboratory G7 Ripple Filter Systems of the Zero Gradient Synchrotron and Means for Long, Magnetically-Controlled Beam Spills , Edward J. Barsotti, Walter F, Praeg, and James M. Stephenson, Argonne National Laboratory G8 Modifications to the ZGS Ring Magnet Power Supply Generator Excitation Control , John F. Sellers and Alfred Rohrmayer, Argonne National Lab- oratory G9 Extended Flattop Operation of Bevatron Results from Generator Dovetail Failure Studies , W. W. Salsig and H. W. Vogel, Lawrence Radiation Laboratory G10 Flat Topping the CEA Alternating Gradient Magnetic Field , R. J. Averill, Cambridge Electron Accelerator, Harvard University Gil High Stability, High Current, Programmed Power Supplies for Nimrod Extraction Systems , F. S. Gilbert, Rutherford Laboratory, England G12 Large DC Magnet Power Supplies at SLAC , Martin M. Berndt, Stanford Linear Accelerator Center G13 Recent Work on Superconducting Synchrotrons , J. D. Lewin and P. F. Smith, Rutherford Laboratory, England G14 Measured Losses in Pulsed Superconducting Magnets , William S. Gilbert, Lawrence Radiation Laboratory G15 Superconducting Synchrotron Magnets , W. B. Sampson, R. B. Britton, G. H. Morgan, P. F. Dahl and J. P. Blewett, Brookhaven National Lab- oratory G16 Operating Experience with a Superconducting Magnet in an Accelerator Experiment , William Chamberlain, Lawrence Radiation Laboratory G17 Fabrication and Operation of Superconducting Beam- Transport Magnets Using Niobium Titanium , Robert B. Meuser, Lawrence Radiation Labora- tory Gl£> High Field Iron Magnets for Operation at Cryogenic Temperatures , G. T. Danby, J. E. Allinger and J. W. Jackson, Brookhaven National Labora- tory G19 Adhesive and Insulating Systems for Cryogenic and Superconducting Coils , F. Markley, A. McKamey and J. Biggs, Argonne National Labora- tory G20 High-Quality Narrow Quadrupole Magnets , K. H. Lou, J. M. Hauptman, and J. E. Walter, Lawrence Radiation Laboratory G21 Design of the ISR Inflect or , H. Kuhn, W. C. Middelkoop, H. 'Hanlon, CERN, Geneva G22 Design and Performance of the Omnitron Septum Test Magnet , K. Halback, D. T. Scalise, and E. H. Hoyer, Lawrence Radiation Laboratory G23 A Gradient Ferrite Pulsed Inf lector for 130-MeV Electrons , T. Dickin- son, Cambridge Electron Accelerator, Harvard University G2<4 The Design of Beam Inflector Magnets for Ultrahigh Vacuum Operation , R. D. Hay, Cambridge Electron Accelerator G25 The Ultraflector Current Switch , L. A. Lav and J. M. Pater son, Cam- bridge Electron Accelerator, Harvard University G26 A System for High Field Pulsing and Demagnetizing of Multipole Magnets in the AGS , U. Vogel, Brookhaven National Laboratory G27 Slow External Beam Ejection Magnets and Power Supplies , H. C. H. Hsieh and A. V. Soukas, Brookhaven National Laboratory G28 Development of the Floating Wire Method for the Control of Complex Optical Systems , J. Jaouen, J. Pinel and D. T. Tran, CSF — Corbeville G29 Differential Analysis of Magnetic Field Measurements with Applications , Jonathan D. Young, Lawrence Radiation Laboratory G30 Computer Solutions for Three -Dimensional Electromagnetic Field Geom - etries , D. Nelson, H. Kim and M. Reiser, University of Maryland G31 Two -Dimensional, Uniform Current Density, Air-Core Coil Configurations for the Production of Specified Magnetic Fields , G. H. Morgan, Brook- haven National Laboratory G32 Iron Magnets Without Air Gaps , G. Parzen, Brookhaven National Labora- tory G33 Investigation of the Characteristics of Ceramic Capacitors for Synchro - tron Kicker-Magnet Application , David L. Smart and Bob H. Smith, Lawrence Radiation Laboratory G34- Electrical Tests of Zero Gradient Synchrotron Magnet Coils , Kostas Burba and Alfred Rohrmayer, Argonne National Laboratory G35 Experience with Aluminum Coil Magnets , Edward Roskowski, Stanford Linear Accelerator Center G36 The Effect of Distorted Voltages in Experiment Areas and Suggested Improvements , Alfred Rohrmayer, Joseph R. Stapay, and Arnold G. Vanderf lught , Argonne National Laboratory G37 The Power and Cooling Interconnection of the 2QQ-GeV Synchrotron Magnets , J. A. Satti, National Accelerator Laboratory G38 Temperature Distributions, Heat Transfer and Resulting Life Expectanc y of Transformer Windings , C. A. Harris and D. R. Walz, Stanford Linear Accelerator Center G39 Round Table Discussion of Heavy Ion Accelerators , R. M. Main, Lawrence Radiation Laboratory; J. A. Martin, Oak Ridge National Laboratory; P. H. Rose, High Voltage Engineering Corporation; C. Schmelzer, Uni- versity of Heidelberg. Moderator: R. S. Livingston, Oak Ridge National Laboratory Session H - Computer Uses, Instrumentation, Controls and Vacuum Systems HI Invited Paper. Computers in Accelerator Control Rooms — A Personal Appraisal , M. Q. Barton, Brookhaven National Laboratory H2 Invited Paper. Beam Detection Using Residual Gas Ionization , W. H. DeLuca, Argonne National Laboratory H3 Qn-Line Computer Monitoring and Optimization of a Multiple Target Proton Beam Line , F. Hornstra, Jr., and R. E. Scherr, Argonne National Laboratory H4 Capabilities and Uses of a Graphic Display System as an Interface Between the ZGS Computer and the Human Operator , L. G. Lewis, M. J. Knott, R. George, C. S. Chien, A. Valente, and G. Gunderson, Argonne National Laboratory H5 Instrumentation and Control of AGS Slow External Beam , J. D. Fox, G. W. Bennett, G. S. Levine, R. J. Nawrocky, L. E. Repeta and A. V. Soukas, Brookhaven National Laboratory H6 The Use of Computer Developed and Generated Displays in the Monitor - ing and Control of Accelerators , R. Frankel, Brookhaven National Laboratory H7 Improving Information Exchange Between the AGS and Its Experimenters , A. R. Watts and G. ¥. Cornish, Brookhaven National Laboratory H8 Computer Controlled Energy Spread Measurement at the CERN PS Linac , U. Kracht, A. Van Der Schueren, U. Tallgren, P. Tetu, CERN, Geneva H9 Fast Automatic Beam Momentum Analyzing System for a 300-nsec, 300- Ampere, 3 to 6-MeV Electron Beam , J. F. Ryan, W. A. Sherwood, and M. E. Smith, Lawrence Radiation Laboratory, Livermore H10 Beam Matching, Steering, and Design Using a CDC-924, and Oscilloscope , and Programs Developed at Argonne National Laboratory , Stewart Marco- witz, George Concaildi, and Richard George, Argonne National Labora- tory Hll A Digital Resonance Control System for the Drift-Tube Linac , John B. Sharp and George R. Swain, Los Alamos Scientific Laboratory H12 Stimulation and Measurement of Radial Betatron Oscillations in the Bevatron Using the rf Accelerating System, K. C. Crebbin and F. H. Lothrop, Lawrence Radiation Laboratory H13 Controls for the CERN Intersecting Storage Rings , 0. Grobner, D. Neet, P. Rieben, B. Sagnell, G. Schaffer, R. Scholl, K. Unser, P. Wolsten- holme, CERN, Geneva H14- Computer Control of the PPA Synchrotron , J. Henness, M. Isaila, K. Koepke, D. Sober , W. Yang, Princeton- Pennsylvania Accelerator H15 S1AC Accelerator Control Computer , Daryl Reagan, Stanford Linear Accelerator Center H16 The Process Control Computer at the CERN Proton Synchrotron; Its Application in the Operation of a Fast Ejected Beam , H. Van Der Beken, D. R. Machen, J. H. B. Madsen and Ch. Serre, CERN, Geneva H17 Digital Control of Bevatron External Proton Beam Transport Magnets , Don Evans, Lawrence Radiation Laboratory HIS Zero Gradient Synchrotron Experimental Area Control System , Earl W. Hoffman, Paolo Marcato, David H. Nordby, Leroy G. Parslow, and Frank L. Schweingruber, Argonne National Laboratory H19 Computer-Control for the Maryland Cyclotron , J. Etter, K. Jenkins and D. Nelson, University of Maryland H20 OMNIBUS — A Multi-Programming Executive System for the Zero Gradient Synchrotron Control Computer , M. Knott, A. Brescia, and A. Valente, Argonne National Laboratory H21 Real-Time Executive for a Small Computer System , C. Stewart, Brook- haven National Laboratory H22 A Compact Data Acquisition and Control Terminal for Particle Accelera - tors , D. R. Machen, R. A. Gore, and D. W. Weber, Los Alamos Scientific Laboratory H23 A Versatile Technique for Interfacing a Control Computer with Remote Data Acquisition and Control Stations along Particle Accelerators , F. Duncan Terry, Los Alamos Scientific Laboratory H24- PCM Data Transmission System Using Split Phase Code , Ezra C. Budge, Los Alamos Scientific Laboratory H25 Multiplexing Digital Beam Information Signals to Accelerator Users , F. Greeley, M. Knott, L. Lewis, C. Swoboda, Argonne National Labora- tory H26 Application of Telephone Crossbar Relays to Computer Control of a Particle Accelerator , James W. Davis, Warren L. Dexter, and Bob H. Smith, Lawrence Radiation Laboratory H27 Automated Multiple-Beam Charged-Particle Transport System , Warren L. Dexter, Lawrence Radiation Laboratory H28 Ion Source Control Through High Voltage Isolation Distances Utilizing Photon-Coupled Solid State Devices , Robert L. Bennett, University of Wisconsin H29 Linear Light Link Data Transmission , Ezra C. Budge, Los Alamos Scientific Laboratory H30 The Measurement of AGS Spacial Beam Density Distributions by Means of Flipping Targets , U. Vogel, Brookhaven National Laboratory H31 The CPS Gas-Ionization Beam Scanner , CD. Johnson and L. Thorndahl, CERN, Geneva H32 Beam Profile Monitors for Fast and Slow Extracted Proton Beams , D. A. G. Neerfc, CERN, Geneva H33 Dynamic Beam Profile Measurements at DESY using Synchrotron x-Radiation , ¥. Ebeling, G. W. Bennett, Deutsches Elektronen-Synchrotron H34 Detectors for CEA RF Monitors , B. Anderson, Cambridge Electron Accelera- tor H35 Beam Monitoring at the NBS Linac — Energy, Current, Position, Charge , John L. Menke, National Bureau of Standards H36 Evaluation of High Stability Secondary Emission Monitors , Theodore Deparry and Lazarus G. Ratner, Argonne National Laboratory H37 Picosecond Beam Monitors and Data Acquisition System , N. J. Norris and R. K. Hanst, E. G. and G. H38 Calibrating and Evaluating Induction Electrode Designs Using Cathode Ray Beams , James R. Simanton, Argonne National Laboratory H39 1 " Beam Current Transformer with DC to 200-MHz Range , K. Unser, CERN, Geneva H40 A Pulse-Signal Viewing System for Accelerators , Dale T. Van Buren and Hugh C. Maddocks, Los Alamos Scientific Laboratory H41 Cryopumping the Omnitron Ultra-Vacuum System Using Heat Pipes and Metallic Conductors , N. Milleron and R. Wolgast, Lawrence Radiation Laboratory H42 The Titanium Vacuum Chamber for the Zero Gradient Synchrotron , Willard B. Hanson, Argonne National Laboratory H43 Corrugated Bellows Vacuum Chamber for Fast-Cycling Synchrotrons , R. T. Avery and G. A. Tidrick, Lawrence Radiation Laboratory H44 Elliptical Vacuum Chamber Stresses and Deflections , R. T. Avery and G. A. Tidrick, Lawrence Radiation Laboratory H45 Tests of a Fail-Safe Vacuum Beam Line Using Acoustic Delay and a Fast Closing Valve , R. C. Wolgast, and J. W. Davis, Lawrence Radiation Lab- oratory Session I - Round Table Discussion on Booster Injectors, New Accelerator Ideas, Superconducting Accelerators 11 Round Table Discussion of Synchrotron Booster Injectors , E. D. Courant, National Accelerator Laboratory; J. L. Kirchgessner, Princeton- Pennsylvania Accelerator; J. M. Peterson, Lawrence Radiation Laboratory; K. H. Reich, CERN, Geneva, Switzerland. Moderator: R. Billinge, Na- tional Accelerator Laboratory 12 The Design of the NAL Booster , R. Billinge, S. C. Snowdon, A. van Steenbergen, National Accelerator Laboratory 13 Beam Dynamics Problems in a Multiparticle Rapid Cycling Synchrotron , Frank B. Selph, Lawrence Radiation Laboratory 14 Progress on the German Proton-Synchrotron , F. Arendt, J. Erb, W. Heinz, K.-P. Jiingst, W. Rudloff, U. Siegmund, L. Steiribock, Kernforschungs- zentrum Karlsruhe 15 Design of a 6QQ-MeV Superconducting Microtron , D. C. Sutton, A. 0. Hanson, D. Jamnik, C. S. Robinson, and P. Axel, University of Illinois 16 Strong Focusing Race Track Microtron , J. Aucouturier and H. Leboutet, CSF - Corbeville 17 Some Construction Details for FFAG-Superconducting Accelerators , P. Gerald Kruger and J. N. Snyder, University of Illinois 18 Performance of the Superconducting Injector for the Stanford Linear Accelerator , E. Jones and L. Suelzle, Stanford University 19 Feasibility Study of a Two-Mile Superconducting Linac , W. B. Herrmanns- feldt, G. A. Loew, and R. B. Neal, Stanford Linear Accelerator Center 110 RF Superconducting Materials Research at SLAC , M. A. Allen, N. Dean, Z. D. Farkas, E. L. Garwin, H. A. Hogg, E. W. Hoyt, R. A. McConnell, M. Rabinowitz, and A. Roder, Stanford Linear Accelerator Center 111 Investigation of Superconducting Niobium Cavities at S-Band , H. Hahn and H. J. Halama, Brookhaven National Laboratory 112 Measurements of the RF -Absorption of Superconducting Resonators , P. Flecher, J. Halbritter, R. Hitschold, P. Kneisel, W. Kuhn, L. List, 0. Stoltz, L. Szesci, Universitat Karlsruhe 113 Measurement of Beam Loading Effects in a Superconducting Structure , M. Kuntze, K. Mittag, K. Pack, G. Winkler, J. Vetter, Universitat Karlsruhe 114- Transient Beam Loading in Electron Linear Accelerators , J. E. Leiss, S. Penner, J. E. Rose and J. B. Broberg, National Bureau of Standards 115 Excitation of a Closed Cylindrical Cavity by a Charged Object Moving along the Axis at Constant Velocity , B. S. Levine and A. M. Sessler, Lawrence Radiation Laboratory 116 A Method for Static -Field Compression in an Electron-Ring Accelerator , L. J. Laslett and A. M. Sessler, Lawrence Radiation Laboratory 117 Collective-Ion Acceleration at Very High Energy in a Static Magnetic Field , Nicholas C. Christofilos, Lawrence Radiation Laboratory, Liver- more 118 Theoretical Studies on the Formation and Expansion of a 23-MeV Elec - tron Ring in a Solenoidal Magnetic Field , R. Berg, H. Kim, D. Nelson and M. Reiser, University of Maryland 119 Flat-Topping Magnet Current for the Berkeley Electron Ring Accelerator Experiment , William R. Baker, William L. Gagnon, and Ferdinand Voelker, Lawrence Radiation Laboratory 120 Mechanical Design of Compressor Test Apparatus for "Electron Ring Accelerator" Research , R. T. Avery, H. P. Hernandez, R. M. Reimers, W. W. Salsig, Lawrence Radiation Laboratory 121 Measurement and Optimization of the Emittance of a 300-nsec , 250-A , 3.4-MeV Electron Beam , R. W. Allison, Jr., J. W. Beal, W. L. Everette, J. R. Guggemos, W. A. S. Lamb, R. M. Richter, W. A. Sherwood, R. L. Spoerlein, J. Tanabe, R. E. Wright, and E. Zajec, Lawrence Radiation Laboratory 122 Fast Beam Choppers for the Electron Ring Accelerator , Andris Faltens and Cordon Kerns, Lawrence Radiation Laboratory 123 The Fixed-Field, Rotating -Magnet Synchrotron or: Why Pulse? , M. L. Good, State University of New York at Stony Brook 124 A Polarized Photon Beam for the SLAC 82-Inch Hydrogen Bubble Chamber , Charles K. Sinclair, Tufts University; Joseph J. Murray and Paul R. Klein, Stanford Linear Accelerator Center; Monroe Rabin, Lawrence Radiation Laboratory 125 A Laser Induced Compton Back- Scattered Photon Beam at the -Cambridge Electron Accelerator , Jon R. Sauer, Richard H. Milburn, and Charles K. Sinclair, Tufts University; Mircea Fotino, Cambridge Electron Accelerator Session J - Plenary II Jl Invited Paper. Electron Positron Storage Rings; Status and Present Limitations, Fernando Amman, CNEN-Frascati J2 Invited Paper. Superconducting Synchrotrons , Michael A. Green, Lawrence Radiation Laboratory J3 Invited Paper. Structures for Superconducting Electron Linacs and RF Separators , P. B. Wilson, CERN, Geneva J4 Invited Paper. The Stanford Superconducting Linear Accelerator Project , W. M. Fairbanks and H. A. Schwettman, Stanford University J5 Invited Paper. Refrigeration for Superconducting and Cryogenic Sys - tems , T. R. Strobridge and D. B. Chelton, National Bureau of Standards J6 Invited Paper. Accelerator Power Systems , G. K. Green, Brookhaven National Laboratory tPresented orally. INVITED PAPER Al. Accelerators and the World Around Us . DENIS M. ROBINSON, High Voltage Engineering - To what extent have ac- celerators and the "basic science associated with them "been useful to the public, as a whole; to the layman, to the national life? An impressive answer can be given; the contribution has been enormous, it is well documented and ac- knowledged among scientists. In hard economic terms, it has had a greater payoff than any science investment yet. However, that remarkable record has not saved university and national accelerator programs from being hurt by the capital and operating budget limitations of recent years. When we ask for money support, the question comes back: "What have you done for us lately?" or "What are you doing for health, cities and air pollution?" Scientists en- gaged in basic work and teaching know that science must be supported anyway and they reiterate what we all know: — that a large proportion of the great breakthroughs, of technology come as a result of basic scientific inquiry, but that useful applications are inherently unpredictable. This difference of aim and priority is nothing new. It has been the rule rather than the exception in the past and in other countries. The pure scientist, like the artist, has never really been understood by the men and institutions who supported him at the time . This dichotomy between people seeking immediate solutions to present problems and those leading the search for knowledge of the physical world is itself basic and necessary. We can learn to keep it working for us as it has in the past. To do this we must have a united viewpoint that can be expressed and understood by the press, the public, and the Congress. Basic science and its applications must have equal priority and together they must have their essential place in the national scheme. INVITED PAPER A2. Serpukhov 70-GeV Proton Synchrotron Start-Up and Adjustment . A. A. NAUMOV, Institute of High Energy Physics , Serpukhov , USSR. INVITED PAPER A3. The 200-GeV Accelerator . T.L. COLLINS, National Accelerator Laboratory - The paper includes a dis- cussion of construction plans for the 200-GeV accelerator with emphasis on the overall design and site master plan. INVITED PAPER Ak. Collective Method of Proton Acceleration. V.P. SARANTSEV, Joint Institute for Nuclear Research, Dubna INVITED PAPER A5- The Electron-Ring Accelerator .* D. KEEFE, Lawrence Radiation Laboratory - Intensive studies relating to elec- tron rings as vehicles for accelerating protons are under way at the Lawrence Radiation Laboratory; an experimental program has been in progress for about a year. With the U-MeV 0.1-A Berkeley linac, low-current rings were formed and compressed from a radius of 20 cm to 7 cm. In more recent experiments at the 3-3-MeV 200-A Astron injector in Livermore, high-current rings were successfully compressed to a final radius of 3-5 cm and a final energy of 19-0 MeV. The continu- ing program of electron-ring research is described. *Work done under the auspices of the USAEC . INVITED PAPER Bl. Some C onsiderations Associated with Accelerator Ion Sources .* TH.J.M. SLUYTERS , Brookhaven National Laboratory - The advance in ion source technology for dc beams was summarized by G. Kelley during the previous accelerator conference. In the present report the emphasis is on pulsed ion sources for accelerator use. Construction of reliable operating sources is well under control in most laboratories. Beam currents are available up to one ampere; this seems to be more than sufficient for present and near future machines. The accelerator ion source designer needs also to create good beam optical qualities of the ion emitter. Only a few of the large number of ion source publications (about 50 per year) discuss this problem (Orsay, Saclay and Brookhaven) . We summarize the operating parameters of accelerator ion sources with references for more detailed information. We mainly discuss, however, the physical mechanisms of initial shaping and control of the ion emitter in duoplasmatron sources and related problems . ♦Work performed under the auspices of the USAEC . B2.t A Mass Analyzer System for the High Voltage Ter - minal of a Van de Graaff Heavy-Ion Accelerator . F. G. RUEDENAUR, Massachusetts Institute of Technology - A computer analysis of an electromagnetic mass analyzer system which will be mounted in the high voltage terminal of a planned 3~MeV van de Graaff heavy-ion accelerator at MIT has been performed. Since one of the main fields of application of this new facility will be ion implan- tation, a stigmatic focusing analyzer with high trans- mission is required. It is shown that a magnetic sector field which is formed by plane inclined pole faces meets both these requirements. Second order ion optical cal- culations for this type of field are given and compared with two more conventional alternatives of stigmatic focusing analyzers, namely the homogeneous field fringe field focusing magnet and the rotationally symmetric field with logarithmic field gradient n = §■. The com- plete ion-injector system which will consist of a high temperature metal ion source, an extraction and focusing system, and a stigmatic double -focusing mass analyzer will have a total weight of about 400 pounds and be capable of unit mass resolution at least up to mass number 150. B3 . t An Ion Source for Negative Heavy Ions . M. MUELLER AND G. HORTIG, Max-Planck-Institute, Heidel - berg - An ion source 1 based on the secondary ion emis- sion from a rotating plate covered with caesium yielded negative ion currents of more than 10 yA of Ag" and Au~ in a first test. Technical details and recent results on different materials are presented. iHortig, G., P. Mokler, and M. Mueller, Z. Physik 210, 312 (1968). BU. Ion Source Modification for He Ions . G. F. WELLS and J. W. JOHNSON, Oak Ridge National Laboratory - The charge exchange canal of the standard HVEC negative ion source has been modified to accept a 250-watt heater, metal-vapor source, and cooled baffles. The new canal is designed to utilize the alkaline earth metals (Mg, Ca, Ea, Sr),all of which produce sufficient vapor for charge exchange below their melting points. Experience indicates calcium to be the best He" ion producer; 1.2p,a of He" ions and 0.7p,a of He ++ ions are obtained in the analyzed beam at 10 MeV. All the metals tried are much superior to the gas canal previously used. ♦Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation. B5. Inert Gas Ion Beams from a Duoplasmatron Ion Source . N. WELLS AND P. R. HANLEY, Radiation Dynamics - Operational characteristics of a Duoplasmatron ion source were examined for milliampere positive ion beams of he- lium and argon. Ion beam current was measured as a func- tion of extraction voltage for various source arc and source magnet currents. With the source parameters fixed, the data exhibits a critical voltage, above which the target current saturates and is independent of ex- traction voltage. This saturation current is linearly dependent on the source arc and source magnet currents. Below the critical voltage, the target current can be described by a v3' 2 dependency on extraction voltage. These observations indicate that the ion current extrac- ted from the plasma is only dependent on the source parameters and thus on the ion flux through the anode aperture. Results are compared for strong-field and weak-field extractor electrodes, which confirm that the total current extracted from the plasma is independent of the extraction field strength. B6 . High Current, Continuous Duoplasmatron Ion Source . JOHN H. 0RMR0D, AECL, Chalk River - A duoplasmatron ion source has been operated at currents of 100 to 200 mA for periods up to several days . The ion source test stand is evacuated by both diode and triode ion pumps and opera- tion under prolonged hydrogen pumping will be discussed. Plasma transport through the anode aperture has been measured for variations of the aperture diameter, hydro- gen flow, arc and coil current. Results of life tests will be given. B?. Test of LASL Ion Source with 200 -kV Pierce Ac - celerating Column .* C. R. EMIGH, E. A. MEYER, AliD D. W. MUELLER, Los Alamos Scientific Laboratory - A 200- kV test stand has been constructed for evaluation of a high-duty factor ion source capable of producing a 30-mA beam of protons of high quality (emittance <-o-cr.- mrad) . The ion source is a Von Ardenne duoplasmatron with a large expansion cup. The beam extraction is ac- complished by an exact "Pierce" geometry accelerating column. The anode of the Pierce column is biased to the plasma potential to reduce rim distortion, which usually is associated with large plasma extraction sur- faces. Special cooling is necessary for this high-duty factor ion source. The test stand vacuum system uses a 1000-t/sec ion pump which is capable of continuously handling the 2 cc-atms/min hydrogen throughput of the ion source. The pumping cells of the ion pump are expected to have a useful life in excess of 1+000 h. The test stand can be operated completely by computer control. ♦Work supported by the USAEC. B8. The "HIPAC" as a Source of Highly Stripped Heavy Ions .* J.D. DAUGHERTY, J.E.EHINGER, G .S . JANES AND R.H. LEVY, Avco Everett Research Laboratory - In the "HIPAC" ion source concept, a cloud of electrons (n e ~ 2 X 10 10 cm -3 ) is contained in a toroidal vacuum chamber (minor radius ~ 10 cm, major radius ~ 50 cm) by an azi- muthally symmetric magnetic field (~ 3 kG). The azimuth- ally symmetric space charge (of the electrons) creates a topologically closed potential well in which ions can be trapped (Z e ffni ~ 2 X 10 9 cm -3 ). In addition, the elec- tron cloud rotates perpendicular to the magnetic field with a characteristic speed E/B < 10 10 cm/sec. This translational motion of the electrons allows one to con- sider the electron cloud as equivalent to a 100-MW beam whose power is almost wholly reactive (energy ~ 1 joule, rotational frequency ~ 100 MHz). The ions do not rotate with the electrons and will therefore become highly stripped in times like 0.1-10 sees. Mean production rates of stripped ions are expected to be 10 13 ions/sec for Kr +2 ° or 10 11 ions/sec for U* 80 . The major problems involved in matching this ion source to a variety or ac- celerators (cyclotrons, linacs, potential drop machines, synchrotrons) are briefly reviewed. The current status of theoretical and experimental work on the concept is discussed in an adjacent paper. ♦Supported by Contracts AEC (AT (30-1) -3863) and AF0SR(AF ^9(638)-l553). B9. Current Status of the "HIPAC" Source of Highly Stripped Heavy Ions .* J.D. DAUGHERTY, J.E. ENINGER, G.S. JANES AND R.H. LEVY, Avco Everett Research Labora - tory - Present experimental work on the "HIPAC ' Ion Source concept has had the objective of exhibiting both the establishment and the containment of the required elec- tron cloud. Two toroids have been constructed, each having major radius ~ 50 cm, and minor radius ~ 10 cm, magnetic field ~ 2 kG and magnetic induction volt- age ~ 3 kV. The vacuum level in the Mk I torus is ~ k X 1CT 7 torr, while the Mk II has been operated at 10~ 8 torr and is expected to reach significantly lower values. Injection of electrons from a circumferential filament (bias > 1 kV) is accomplished using the induc- tion associated with the rising magnetic field. Average electron densities ~ 7 x 10 9 cm -3 have been achieved, giving potential well depths > 300 kV. Both the elec- trons and the ions formed by ionization of the residual background gas are contained until the density of the ions ni exceeds 10-20$ of n e . Containment time has been found to increase with decreasing pressure and has reached 1.3 ms at 10~ 8 torr. Interpretation of these results suggests that at a base pressure ~ 10~ 10 torr and with an outgassing rate ~ 10" 12 torr liter/cm 2 -sec, the electron containment time would be long enough to permit substan- tial stripping of the ions . ♦Supported by Contracts AEC (AT(30-l)-3863) and AF0SR(AE k9 (638) -1553). BlO.t Design and Performance of the Sandia Laboratories Hermes II Flash X-ray Generator .* THOMAS HUGH MARTIN, Sandia laboratories - A flash x-ray generator, Hermes II, has been developed and constructed and has produced a bremsstrahlung radiation dose in excess of 6000 rads (H3O) in 0.07 ^is at a distance of one meter from the x-ray target, thus exceeding twice the single-pulse out- put of any similar laboratory source. This bremsstrah- lung dose was produced by a 13-MV, 200-kA electron beam incident on the thick tantalum anode target of the x-ray tube. The oil-immersed generator is contained in a cy- lindrical tank 22 ft in diameter and 80 ft long and con- sists of a Marx capacitor bank as the primary energy store, a coaxial Blumlein transmission line, and an x-ray tube. The Marx bank charges the transmission line to 12 megavolts. The transmission-line energy, upon switching, accelerates an intense electron beam in the x-ray tube. To produce an operable generator, a nominally maximum 18-MV Marx generator had to be developed. Also, oil- immersed switches, oil-immersed transmission lines, support structures , and x-ray tubes have had to operate successfully at voltages exceeding 12 megavolts. *This work supported by the USAEC. Bll. Development of a l8-Megavolt Marx Generator .* D.L. JOHNSON, T.H. MARTIN, AND K.R. PRESTWICH, Sandia Laboratories, Albuquerque - A nominally maximum 18- MV, 1-megajoule oil-immersed Marx generator has been constructed and tested at 12 megavolt as the energy store of the Sandia Laboratories Hermes II flash x-ray machine. The generator has a relatively low induct- ance of 80 microhenries with 186 one -microfarad, 100 kilovolt capacitor stages and 93 individually packaged spark gaps . Model and circuit studies determined a geometrical layout for the capacitors which uses the stage-to-stage stray capacity to provide a wide spark triggering gap range (down to UO percent of the self- breakdown voltage of the spark gaps ) and rapid bank erection time . An analogue circuit study demonstra- ted that charged stray capacities between the gener- ator and the container tank wall produces undesirable voltage transients which can be minimized by trigger- ing the Hermes II generator at selected points . The mechanical support system of the generator minimizes the possibility of arc -over on the support insulators. A pressurized gas spark gap capable of being triggered was designed and used successfully in the Marx gener- ator. The spark gaps operate from !+0 kilovolt to over 300 kilovolt and conduct currents in excess of 100,000 amperes. During the gap development, arc erosion tests determining the degradation of the hold- off voltage with a number of high energy discharges were performed with several electrode materials. A tungsten-copper -nickel alloy was selected as the elec- trode material and a nitrogen-oxygen mixture as the fill gas. These gaps have successfully operated for over 35,000 gap firings in the generator. *This work supported by the USAEC. B12. Dynamics of Electron Beam Flow From Pulsed. High Current "Field Emission" Cathodes .* W. R. McNEIL AND J. R. UGLUM, Ion Physics Corporation - A great deal of data has become available concerning the impedance char- acteristics and current density profile of beams pro- duced by pulsed electron accelerators. A computer prog- gram has been used to explain the details which are* now known for a specified cathode geometry. The same program can also be used to predict the performance of other cathode geometries. The program uses the Lorentz force equation coupled with Maxwell's equations, including the electron beam's interaction with its own magnetic field, to numerically compute the beam flow in a self-consistent manner. Detailed analysis of a 100-ohm, 2-MV cathode is presented, and the numerical results are compared with experimental data. It was found that both the cathode impedance, and electron beam flow, could only be ac- counted for if the emission from the cathode is assumed to be space charge limited. A plausible reason for this limitation is put forward. *Work supported under DASA Contract DASA-OI-68-C-OO5I. B13-t A Monte-Carlo Model for the Heavy-Ion Charge Change Accelerator . G. HORTIG, Max- Planck-Institute, Heidelberg - Monte -Carlo model studies for the heavy-ion accelerator considering charge change, scattering and energy loss in the charge change media are presented. The assumptions for this model and results of the studies concerning limiting effects for the maximum energy, beam diameter, and transmission are discussed. Bll+. The Ion Optic System for the Heavy-Ion Charge Change Accelerator . M. SCHECHTER, G._ HORTIG AND H. SPIL- LECKE, Max -Planck-Institute, Heidelberg - An achromatic ion optic system particularly suited for the heavy-ion charge change accelerator is presented. The system consisting of a straight strong focusing section terminated by two three-component mirrors has been optimized to obtain stab- ility of the ion trajectories in the full range of achro- macy. The system and the optimization procedure are dis- cussed. INVITED PAPER B15. Tandem Accelerators .* H. E. WEGNER, Brookhaven National Laboratory - The latest improvements in the design and performance of multistage electrostatic accelerators are reviewed. Drawings and photographs are used to illus- trate the progress of new accelerators under design and construction in this country. Particular attention is given to the 15-MV Model-TU and 1+-MV high current tandem Van de Graaff accelerators of the High Voltage Engineering Corpor- ation; the Dynamitron high current tandem accelerator of Radiation Dynamics, Incorporated; and the 5-MV source injec- tor and 8. 5-MV vertical tandem that constitute the 22-MeV three-stage Pelletron accelerator of the National Electro- static Corporation. The dynamic capabilities of these new machines and the important role that they will play in the study of nuclear structure physics are described. Finally, there is a brief photographic tour through the large three- stage facilities in the United States including those at Los Alamos Scientific Laboratory, the University of Washington, and at Brookhaven National Laboratory. ♦Work performed under the auspices of the USAEC . Bl6.t The Tandem Dynamitron . P. R. HANLEY, M. R. CLELAND, C. F. MASON, K. H. MORGANSTERN, AND C. C. THOMPSON, Radiation Dynamics - A two -stage tandem accelerator system, powered by a Dynamitron high voltage generator, is currently undergoing factory tests. The parallel-coupled cascaded rectifier generator is designed for a 5~mA current capability at maximum voltage, to accommodate a terminal -mounted Duoplasmatron ion source for single stage operation. A large gas stripping canal replaces the ion source assembly for two stage operation. Titanium sublimation pumps are mounted in the terminal to insure acceptable vacuum conditions in the fully shielded acceleration tubes. Guaranteed specifications of this model series are 100-/ Suppression of Vertical "Jitter" of the Beam from an Inclined Field Tube 3 "Stage FN -Type Tandem V an de Graaff Accelerator .* NANCY J. CALING, HAROLD FAUSrA AND FRED H. SCHMIDT, University of Washington - The tea:: from a tandem accelerator with vertically inclined field tubes undergoes a rapid up and down motion, or jitter. The jitter is caused by an irregular charge density transported by the belt, 1 which induces fluctuating poter tials on the inclined electrodes. The beam jitter is thus a complex pattern repeated each belt cycle; its magnitude varies from l/k to one beam width at the imajje of the first quadrupole lens. For some experiments the beam jitter causes undue scattering from defining aper- tures. Our suppressor system senses the jitter on a pair of adjustable slits placed at the quadrupole iisape. The correction signal is sent to deflection plates located just downstream from the quadrupole. These plates were originally used for vertical steering; this is now accomplished by biasing the quadrupole. 2 The suppressor reduces the jitter to 10$ or less of a bean width, and thus reduces the beam spot area on target by 10 to 50 $• The system has been used successfully for 22 -MeV a. particles, and for protons from 8 to 20 MeV. B20. Wide -Range Van de Graaff Pulser .* E. J. ROGERS, Brookhaven National Laboratory - A unique system for pro- ducing variable length electron pulses from a Van de Graaff accelerator has been developed; it provides pulses with duration continuously variable from less than 0.2 jxsec to an unlimited upper value. The very wide range is achieved by the use of a two-channel control system in which separate light signals turn the beam on and off. The two-channel technique greatly relieves the band-width requirements on the light source and amplifying circuitry in the high voltage terminal. The electron gun control grid, because of its capacitance and large voltage swing, requires a peak power approaching 1 kW to produce switch- ing times of the order of 60 nsec. The high transient power is supplied by a pair of blocking oscillators using small receiving tubes. Their average dissipation is low because they are active only during the switching periods. A single-tube amplifier driven by a flip-flop holds the grid at the required on or off level after switching has been accomplished. Again, a small receiving tube may be employed because the amplifier, not being required to provide switching power , can be operated at low current with a very high load resistance. ♦Supported in part by the USAEC. 1 Unpublished. Nuclear Physics Laboratory Annual Report, University of Washington (I968), p. 171. 2 J. G. Cramer and F. H. Schmidt, Nuclear Instr. and Methods Vj_>325 (1966). Bl8. Magnetically Suppressed Tubes for Electrostatic Accelerators . F. A. HOWE, AERE, Aldennaston, England - Magnetically suppressed tubes of the design detailed in the paper presented at the 1967 Conference 1 have now been installed and operated in both single and tandem stage electrostatic accelerators. The results of these opera- tions are presented and discussed, together with various other aspects of design and pre-installation testing. X F. A. Howe, IEEE Transactions on Nuclear Science, NS-lU. No. 3, 122 (1967). ♦This work was performed under the auspices of the USAEC. B21. Selection of a Vac-Ion Pump for a Terminal Ion Source . ♦ J. A. BENJAMIN, Brookhaven National Laboratory - An 800-l/s electrostatic ion pump and a 500-1/s magnetic triode ion pump have been tested to determine which would be most suitable for pumping the hydrogen gas emanating from a duoplasmatron ion source . , The ion source and pump will be located in the terminal of a HVEC Type MP tandem accelerator. The two pumps were mounted on a pump test stand with a manometer, two needle valves, and two ion gauge controllers. The hydrogen flow to each pump was increased slowly until the pump was near the point of pressure instability. Flow rates and pressures were recorded for about 1000 hours. The performance of the magnetic triode ion pump was superior to that of the electrostatic pump. The magnetic triode ion pump is presently undergoing another teat, pumping the hydrogen gas from a duoplasmatron ion source test stand. Pumping speed measurements, modes of failure, and other details of these continuing tests will he presented. *Work performed under the auspices of the USAEC. loading effects are more severe with molecular ions. The data suggest that the goal of 5 "to 10 mA of protons can he achieved through the proper use of vacuum pumping and mass analysis prior to acceleration. B22 . A High Speed Gas -Handling System for the Brook - haven national Laboratory Three-Stage Tandem Van de Graaff Facility .* K. F. MINATI, Brookhaven National Lab - oratory - A high speed gas handling system for the insula- ting gas of two MP Van de Graaff accelerators has been installed at the Brookhaven National Laboratory three- stage facility. The system was designed to complete all phases of the gas handling function (except drying) in less than 4-X/2 hours. A complete pumping cycle consists of pumping gas to storage, ventilating the tank, evacua- ting air from the vessel and gas filling. To avoid ther- mal shock to the fragile structure within the 11,000 cubic foot accelerator vessel, the gas cycling should be accomplished with a temperature change of less than 10°F per hour and a maximum temperature gradient within the tank of less than 10°F. Heat load calculations indicated that an external heat exchanger, recirculating blower, and temperature controls -were required. The pumping speed of the reciprocating gas compressor has been sub- stantially improved, without any increase in horsepower, by utilizing a high pressure first-stage cylinder de- signed to accept accelerator tank pressure throughout the pumping cycle. A description of the mechanical equipment and temperature controls will be presented, together with some actual performance data. *Work performed under the auspices of the USAEC. B23. High Voltage Insulators for Particle Accelerators .* K. D. SRIVASTAVA, University of Waterloo, Canada - In modern high energy particle accelerators many component parts and devices, e.g., dc injectors, electrostatic in- flectors, beam choppers and velocity separators, operate in vacuum at high voltages. Since the surface voltage stress attainable across insulators is generally lower than across plane gaps, the physical size of the high voltage apparatus is governed by the high voltage per- formance of support insulators in vacuum. This perform- ance is affected by the residual gas pressure and com- position, insulator shape and material, the design of the triple (insulator-electrode-vacuum) dielectric junc- tion and the nature of the applied voltage, pulsed or dc. In this paper the author discusses the relative impor- tance of the above factors in the light of his experience with NIMROD, the 7-Gev proton synchrotron, and with the design of a dc injector for the proposed Chalk River Intense Neutron Generator. Some results for ceramic oxide conductive surface coatings are also discussed. *The work supported by AEC Ltd., Canada. B2k, Acceleration of Intense Positive Ion Beams at Megavolt Potentials . M. R. CLELAND, P. R. HANLEY, C. C. THOMPSON, Radiation Dynamics - The long range objective of the ion accelerator development program at RDI is to achieve a proton beam current of 5 to 10 mA at 3 to 5 MeV energy. Present performance is limited to 3 mA of mixed hydrogen ions at 3 MeV and 2 mA at k MeV, despite the fact that both ion source and high voltage generators are capable of 10 -mA service. Symptoms of excess ion beam loading are: rapidly increasing vacuum, X-ray pro- duction, leakage current, and beam halo. These observa- tions can all be explained through the mechanism of scattering of the beam by residual gas in the accelera- tion tube. This effect is regenerative because scattered particles release more gas from the tube electrodes. The problem has been substantially reduced by a titanium sublimation pump at the high voltage terminal. In addi- tion to the pump, a crossed-field mass analyzer has been operated in the terminal. Comparative data on machine performance with analyzed beams has shown that the B25> High Voltage DC Power Supplies for Eeam Injectors . GUNTER REINHOLD, Emile Haefely & Co., Switzerland - During 1969 three 850-kV dc power supplies will come into operation for beam injection into high energy acceler- ators now under construction at LASL, BNL, and NAL. These air -insulated power supplies use a symmetrical cascade generator and an accelerator structure which will accept the ion source and its auxiliary equipment. A 15-kW motor -generator set with an insulating shaft is used to energize the equipment at high voltage potential. The dc power supplies are rated at a maximum operating voltage of 85O kV dc and are designed to provide current pulses from 0.1 to 0.5 A with pulse lengths from 500 to 100 usee at repetition rates from 120 to 10 c/s. The overall stability of the accelerating voltage between and during the pulses is better than 1 x 10"3. A fully electronic ac supply and coarse regulating system is used to energize the cascade generator and to stabilize its dc output voltage. The fast regulation from the beginning until the end of the steep current pulses is achieved by a regulating system that utilizes a bouncer. B26. Pressurized 1-MeV Electron Accelerator of the Twin-Tank Design for Electron Microscopy . GUNTER REINHOLD, Emile Haefely & Co., Switzerland - Since the beginning of this decade the first high voltage electron microscopes designed as research facilities with energies from 0.5 to 1.5 MeV have come into operation. The electron beam is injected into the microscope columns from electron accelerators; this requires an extremely high stability of the accelerating voltage. Fully electronic ac supply and regulating systems have been developed in connection with the symmetrical cascade generator which approach an actual overall stability of one part per million with commercially available accelerators. Practical experi- ence has proven, however, that ac interference between the high voltage generator and the accelerator will pro- duce ripple voltages and noise that will neutralize the effect of the regulating and filter systems. To achieve an ultimate stability of 1 x 10 - 6, or even higher for future applications, this problem has led to the design of the pressurized 1-MeV twin-tank accelerator with the high voltage generator and the accelerator located in separate vertical tanks. The units in the two tanks are interconnected by a high-ohmic damping resistor in a horizontal pressurized connection pipe. This system provides perfect electrical shielding and can easily be extended towards higher accelerating voltages. B27. Design Equations for Dynamitron Type Power Supplies in the Megavolt Range . C. C. THOMPSON AND M. R. CLELAND, Radiation Dynamics - The power supply for the accelerating potential of the -megavolt Dynamitron accelerators is a parallel-fed, series-cascaded rectifier system. Low-frequency rf voltage is capacitively coupled into the cascaded rectifier system by means of an SF-6 gas insulated electrode configuration. Maximum voltage attained with this configuration has been 5-0 MV. Maxi- mum current attained has been 20 mA. Maximum beam power attained has been 40 kW. This paper covers the develop- ment of equations which express the operational input parameters, such as: oscillator plate voltage, current, and power in terms of the required output high voltage and load current, and the internal circuit parameters such as, tank capacitance, tank inductance resistance, number of rectifier stages, and oscillating frequency. Calculated data from these equations agree closely with experimental data. This analysis allows the optimization of a power supply design in terms of critical parameters for a given maximum output voltage and load current . B2o. Performance and Modifications of a 200-keV Heavy- Ion Accelerator Facility .* ROMAN LAUBERT AND RICHARD K. ROBINSON, New York University - The air insulated 200-keV heavy ion accelerator 1 has been in operation for more than four years at our laboratory. We report on our experience with this machine and present typical mass analysis spec- tra for various gases (02, Ne, CO, Ar, etc). The magnet- ic analyzing system has a stability of better than 0.01% without a feedback network. The four-ton analyzing mag- nets are mounted on pneumatic feet to allow positioning of the two magnets in any desirable configuration. The vacuum system that permits us to bombard targets without the buildup of a carbon layer is described. At the pre- sent time we are involved in a program to double the machine energy. This is accomplished by using a UOO-keV 3-mA 0.1% regulation Cockcroft-Walton high voltage power supply built by Universal Voltronics Corp. Additional regulation (to 0.0.1%) is achieved by using a de-rippler circuit and feedback that utilizes sensing of the ion beam after mass analysis. *Work supported by the USAEC. 1 R. Laubert and N. Wotherspoon, IEEE Trans. Nucl. Sci. 12, 285 (1965). B29 . The Injector Complex for the LAMPF Accelerator . * P. W. ALLISON, C. R. EMIGH, AND R. R. STEVENS, JR., Los Alamos Scientific Laboratory - The present planning and design goals for the injector complex include a high- intensity H + beam, an H beam, and polarized H + and H" beams. Since simultaneous acceleration of H + and H~ beams will be attempted by the LAMPF accelerator, a dual beam transport system for blending these beams into a common channel will be necessary in the injector area. Provision also is made for injecting either H or H" polarized beams into the system. A high quality bear of protons (if cm-mrad emittance and 26 mA) has been produced by a Von Ardenne duoplasmatron and a "Pierce" extraction accelerating column. The problems of simultaneous bunch- ing and beam matching of H and H beams of different intensities have been studied. The entire injector com- plex is under computer control and should provide reasonably sophisticated pulse programming flexibility. ♦Work supported by the USAEC. B30 . A Polarized Ion Source for the Berkeley 88-Inch Cyclotron .* A. LUCCIO, D. J. CLARK, D. ELO, P. FRAZIER, D. MORRIS, M. RFNKAS, Lawrence Radiation Laboratory - A polarized proton and deuteron source has been built for the cyclotron. The source of the atomic beam type is of classical design, with a 5 0- cm sextupole and two rf adiabatic transitions. The atomic beam is ionized by electron impact and injected axially into the cyclo- tron. Design and performances of the source are des- cribed. B32. Some Results of Studies of Proton Beam Production and Transport for PLANIM . T. R. WALSH, et al, Rutherford Laboratory, England - PLANIM is a proposal to replace the 15- MeV Nimrod injector by the existing 50-MeV Proton Linear Accelerator. It calls for a new pre -injector to provide 75 mA of protons, a new linac tank of 6.5-IO MeV and a 200-m beam line with achromatic benders and inf lec- tor. This paper discusses a number of design problems of the system. An alternative third-harmonic booster is briefly considered. B33- Post Acceleration Beam Pulse Length Chopper . R. J. AVEPILL AND T. L. COLLINS,* Cambridge Electron Accelerator , Harvard University - The CEA 130-MeV linac has a pulse length of 2 jj,s, and the 6-GeV synchrotron accepts only a 0.7-u.s pulse length. To try to inject the entire 2 ^s pulse results in unnecessary radiation damage to vacuum chambers and various portions of the transport system. It is desirable to inject only a 0.7-p.s pulse, and to select, empirically, that portion of the linac pulse that has the least energy spread. The unwanted portion of this pulse should be deposited on a suitably designed beam stop- per . A system of bias magnets and a pulsed f errite magnet followed by a water-cooled collimator has been installed and precisely chops the 130-MeV linac pulse. The injected pulse chosen has the smallest energy spread. The overall system has been designated PAC for post accelerator chopper. The PAC system, and our experience with it, are described. ♦Present address: National Accelerator Laboratory, Batavia, Illinois. B3 1 *-. Operation of a k-mA Dynamitron as a Monoenergetic Neutron Source . P. P. HANLEY, Radiation Dynamics ; A. W. HABERL AND A. TAYLOR, Cornell University - The Cornell Dynamitron is being used as a source of monoenergetic neutrons in the 30~500 keV range, with fluxes up to 10-Wstr-sec. Problems of generating and handling the 2-MeV, 4-mA beam are discussed, together with targets and projected performance for other energy ranges. Analyzing magnet slit feedback is essential for accurate control of neutron energy. Contrary to other published data for these machines, we observe up to 3$ drift in the energy when it is controlled by the voltage feedback system. Discrepancies between this and previously published data are discussed. B35- Performance of the Cornell 10-GeV Electron Synchrotron . M. TIGNER, Cornell University - A report on the characteristics of the Cornell machine during its first year of operation is given. Service record sum- maries will be presented, and a description of major improvements made during the year will be given. * Support received from National Science Foundation. ♦Work performed under the auspices of the USAEC. B3L Production and Acceleration of Deuterium and Helium Ions . A. PASSNER, T. BERTUCCI0, M. ISAILA, D. SOBER, K. V0SBURGH, Princeton -Pennsylvania Accelera - tor - In response to the growing interest in high energy D and He ++ ions, studies were made to determine the feasibility of accelerating these ions in the PPA. The studies indicated that to accelerate D + ions to 600 MeV, the rf would have to operate at the 12th harmonic; to produce 2.4-BeV D + ions, the rf would operate at the 8th harmonic. An attempt was successfully made to accelerate D + at the 12th harmonic; a beam of ~ 6 x lO^DVsec was obtained at 600 MeV. An effort is now being made to accelerate D + on the 8th harmonic. In addition, an attempt is being made to obtain a useful beam of H e ++ ions. B36.+ Operation and Performance of the UW Physical Sciences Laboratory Electron Storage Ring .* E. M. R0WE, R. A. 0TTE, C. H. PRUETT, AND J. D. STEBEN, University of Wisconsin - A 2U0-MeV electron storage ring has been put into operation at the Physical Sciences Laboratory of the University of Wisconsin. The storage ring injec- tor is a 50-MeV FFAG electron synchrotron. The bunched beam from the synchrotron is injected into the storage ring in a single turn. Radio -frequency capture may then be accomplished by one of three methods: adiabatic cap- ture, injection into standing buckets, or by "self-cap- ture." The latter process involves using the signal from the bunched beam as the master oscillator during capture. After capture the beam may be held at any radius in the radial aperture of the ring, which is about 6 cm. The beam may be accelerated, or decelerated, to any energy within the capability of the ring - 10 MeV to 2U0 MeV. The vacuum system operates in the mid 10"10 range permitting life times of many hours for low inten- sity beams. During initial operation several interesting effects have been observed. Among these were photo etching of metal from the vacuum chamber by synchrotron radiation and enhanced beam loss due to scattering from ions trapped in the electron beam. These and other effects are discussed. *Work supported by the U.S. Scientific Research. Air Force Office of B37.t Accelerator Development Activity of the Radio- technical Institute, USSR Academy of Sciences . A. L. MINTS, Radlotechnlcal Institute of the USSR Academy of Sciences , Moscow. B^O. Design and Construction of Physical Facilities, AGS Conversion Project .* J. H. LANCASTER, Brookhaven national Laboratory - The $1+7,800,000 Alternating Gradi- ent Synchrotron Conversion Project includes $17,500,000 for the design and construction of buildings, utilities, and structures. The design philosophy, basis of design, construction schedules, and construction costs are dis- cussed and illustrated for the 200-MeV linac building, experimental building, increased radiation shielding, modifications to the existing magnet enclosure, special building to house the main magnet power generator and high level radiofrequency equipment, new experimental area, seven new and modified cooling water systems for machine and research use, and for utilities and site work. B38. Simultaneous Multiple Targeting Techniques .* L. G. RATTIER, F. H0RKSTRA, S. MARCOWITZ, T. R0MAN0WSKI+, R. SCHERR, Argonne national Laboratory ; N. REAY, Ohio State University - During 1968 two new internal targeting modes were successfully tried in the Zero Gradient Syn- chrotron. These modes will substantially increase the utilization of the ZGS by giving beam to several beam lines on the same machine pulse for the entire length of flat-top. The first of these modes, using .two targets l80° apart, was tried in preparation for utilization of the second extracted proton beam area. Beam intensity could be arbitrarily divided on the two targets for the full 750-msec flat-top. Additionally, secondary particles from one of these targets can provide a pion beam into the meson area. Measurements of emittance showed no sig- nificant change from previous single-target extraction. The second mode utilized beam-sharing on two targets located about five feet apart in the magnetic field of the ZGS ring magnet. In this case, an extracted proton beam was delivered into area one; a neutron beam at 1° production angle and a pion beam were delivered into the meson area. It appears possible to combine these two modes and thus be able to provide a 750-msec spill into four different beam lines on each machine pulse. *Work performed .under the auspices of the USAEC. tAlso at Ohio State University. *Work performed under the auspices of the USAEC . B39- Bevatron External Proton Beam Facilities . T. ELI0FF, R.J. FORCE, W.D. HARTS0UGH, AND K.H. LOU, Lawrence Radiation Laboratory - The first Bevatron exter- nal proton beam system became operational in 1963- The successful operation of this system together with the ad- vantages of an external beam has resulted in heavy reli- ance on this facility by the experimental program. This warranted further development to increase the number and independence of target stations . The initial single chan- nel system with series targetting at three foci operated from 1963 through 1967- In early 1968, a new system was installed in which the extracted beam was split into two channels, each having two target stations. This change, together with other improvements, more than doubled the experimental capability of the facility. As many as eight experiments now operate together utilizing the ex- ternal beam under varied beam spill conditions . The operation of this system is described together with de- tails of shielding, utilities, and physical facilities. In mid-1969, further improvements will be made. One of the present channels will be split via septum magnets to eliminate the limitations imposed by the intermediate focus in this channel. This will provide maximum flexi- bility at each target 'station. An additional station for direct experimental use of full energy protons will be provided. In addition all external beam magnets will be computer controlled. INVITED PAPER CI. Beam Dynamics in Circular Accelerators ■ L. SMITH, National Accelerator Laboratory - A review will be presented of the concepts and computational techniques which have been applied to behavior of particles in circular accelerators in recent years. The Hamiltonian formulation of particle dynamics, which is wide- ly used now for one-dimensional problems, has implications for two- and three-dimensional problems which are not yet fully understood, but which are very relevant to the manipulation of beams in the increasingly complicated applications under consideration today. For high intensity accelerators, in which collective effects influence particle motion in an important way, much can be learned from the field of plasma physics. Examples will be given of phenomena which can be treated more directly by these methods than by the more conventional methods of accelerator orbit theory. C2 . t Beam Amplitude Behavior upon Crossing a Linear Coupling Resonance with Damping in One Dimension . M. J. LEE AND E. D. COURANT, Brookhaven National Labora - tory; C. PELLEGRINI, Laboratori Nazionali di Frascati ; A. M. SESSLER, Lawrence Radiation Laboratory - Single particle behavior, in the neighborhood of the coupling resonance V x + Vz = 1, is studied in the presence of a damping term, proportional to ?,, in the equation for p z . The equations of motion are transformed to phase -amplitude form. Numerical studies of amplitudes, as a function of rate of resonance crossing and amount of damping, will be presented. For sufficient damping, after passage through the resonance the vertical amplitude has hardly increased while the radial amplitude has grown signifi- cantly; which may explain observations, on the ZGS, of beam behavior in the presence of a damping electrode. More interestingly, the calculation suggests the possi- bility of generally controlling resonant beam growth, by means of damping electrodes. *Research supported by the USAEC. C3 • t Transverse Space-Charge Effects in Circular Accelerators .* FRANK J. SACHERER, Lawrence Radiation Laboratory - Particles in an accelerator interact with one another by electromagnetic forces and are held to- gether by external focusing forces. Such a many-body system has a large number of transverse modes of oscil- lation (plasma oscillations) that can be excited at characteristic frequencies by errors in the external guide field. For simplicity we consider only one- dimensional beams that are confined by harmonic poten- tials, and only small-amplitude oscillations. The linearized Vlasov and Poisson equations are used to find the twofold infinity of normal modes and eigen- frequencies for the stationary distribution that has uniform charge density in real space. In practice, only the low-order modes (the dipole, quadrupole, sex- tupole, and one or two additional modes) are serious, and the resonant conditions for these modes are located on a tune diagram. These results, which are valid for all beam intensities, are compared with the known eigen- frequencies for the stationary distribution that has uniform particle density in phase space, and are extra- polated to the Gaussian distribution observed in the Brookhaven AGS . *Work supported by the U. S. Atomic Energy Commission. CU.t The Effect of Tons on the Symmetrical Throbbing Beam Mode . H. G. HEREWARD, P. L. MORTON, K. H. SCHINDL, CERI1, Geneva - Previously, the quality of vacuum neces- sary in an accelerator was determined by the acceptable beam enlargement due to scattering on the residual gas. It has been demonstrated that the presence of ions pro- duced by the beam can cause unstable transverse beam oscillation in a way similar (apart from a sign differ- ence) to the effect of a vacuum chamber with finite con- ductivity. For some of these modes it is possible to design feedback systems to damp the unstable oscilla- tions. However, the symmetrical throbbing mode, where the radius of the beam oscillates, produces rather little field outside the beam itself and would therefore be very difficult to stabilize by feedback. It may even be mistaken for an incoherent instability. Growth rates and stability criteria are determined and numerical examples presented. They demonstrate that the need to control this throbbing beam mode may determine the vacuum requirements for future accelerators. C5.t Collective Effects in Accelerators . A. A. KOLOMEN- SKI and A. N. LEBEDEV, Physical Institute of the USSR Academy of Sciences . Moscow. C6. Damping Bunch Shape Oscillations in the Brook - haven AGS . E. C EAKA, Brookhaven National Laboratory - Bunch shape oscillations* are present in the AGS, both before and after the transition energy (rs 8 3eV) is reached. At transition, they can be excited by timing, phase and radial Disadjustments, and beyond by rapid large radial position changes used for targeting or by rapid large (>20$) targeting losses. They can also be excited before transition by misad justing the low level rf control system. In addition, excitation before tran- sition can occur when 2f = 720 — the magnet ripple fre- quency or when 2f s = 36O ~ the ripple frequency on the rf cavity tuning servo systems. An analysis of the rf phase control system 2 including second order effects 1 indicates that it should damp these oscillations but at a rate ~ f S /By , except in the vicinity of transition. At 200 msec, E rs 6.5 BeV, y=s 6.9, f s ^ 200 ~ and the damping rate is rs 0.1+6 sec" 1 . Thus, adequate inherent damping is present only early in the acceleration cycle. This, plus the fact that the sensitivity of the phase control electronics to bunch shape variations can at times produce antidamping, has led to the design and testing of various feedback damping systems to control these oscillations. An analysis of rf phase and ampli- tude feedback, using a peak detected signal, 1 as applied to the rf control system, will be given. Operational results for both types of feedback will be described. *Work carried out under the auspices of the USAEC. 1 H. Hereward, Proc . of 1961 International Conference on High Energy Accelerators, Brookhaven, N. Y., Sept. I96I, pp. 236-2I+3. 3M. Plotkin, E. C. Raka, H. Snyder; U. S. Patent 3,089,092; May 7, 1963. C7. Investigation of Gradient Corrections for the AGS.* J. C. HERRERA AND M. MONTH, Brookhaven National Laboratory - A non-superperiod symmetric gradient per- turbation results in an instability in the vicinity of integer and half- integer v values. By studying the in- tegral form of the equation for the perturbed motion, conditions to any order in the perturbation are found such that the resulting particle motion at these criti- cal v values is periodic for arbitrary initial values of the coordinates of the particle trajectory. Such a peri- odicity implies stable motion in the region of these critical v values. The nature of these corrected peri- odic orbits and the cumulative effects on the motion over many particle revolutions are investigated for the AGS. *Work performed under the auspices of the USAEC. C8. Orbits and Nonlinear Effects in Terms of the Field Coefficients in the Median Plane .* C. S. CHIEN, Argonne National Laboratory - In the circular acceler- ators, the Lagrangian of motion can he derived by con- sidering the azimuthal angle as the independent variable. The equilibrium orbits and betatron oscillations can be obtained in terms of the field coefficients in the median plane. The method has been applied to the fixed field alternating gradient synchrotrons. 1 Here the general application to the circular accelerators will be dis- cussed. In the same spirit, the nonlinear effects can also be studied in terms of these field coefficients. Since the sets of the field coefficients are different at lower and higher energies of the particles, it is pos- sible to predict, at a particular energy, which nonlinear term is most dangerous. of motion are derived for the expansion coefficients, and these are integrated simultaneously with the equa- tions for the centers. Integrals representing space - charge forces, needed in the equations of motion, are evaluated after transformation to the space of the ini- tial values of particle coordinates; this eliminates the need to calculate charge densities. The advantage of our method over one involving disks, MRA, or multiple particles is that the positions and weights of points used in the integrations for space are not fixed from the start of the calculation but are chosen anew for each step in such a way as to maximize efficiency. The accuracy obtained ought to be equivalent to that obtained by using very many more points in one of the other methods. *Work performed under the auspices of the USAEC. ^■Chien, C. S., IEEE Transactions on Nuclear Science NS-1^, No. 3, 552 (1967). INVITED PAPER C 9- Beam Dynamics in Linear Accelerators .* R. L. GLUCKSTERN, University of Massachusetts, Amherst - The uncoupled equations of motion of charged particles in the longitudinal and transverse directions in a linear accelerator in the absence of space charge forces are reviewed. The effect of coupling on the dynamics is introduced and results are obtained for the apparent increase of the projected phase space areas. Questions of nonlinearities , misalignments, focusing field errors, and fringing field couplings are discussed. In the presence of space charge forces, oscilla- tion frequencies are decreased, admittances are changed, and additional couplings and nonlinearities are introduced. These cause further deterioration in beam quality. An effort has been made to identify those particular effects that play the major role in increasing phase space areas. Comparisons are made with detailed three-dimensional orbit com- putations in an effort to sort out the various effects . *Work supported by the National Science Foundation. ClO.t Numerical Calculations on Transverse Emittance Growth in Bright Linac Beams . P.. CHASMAN, Brookhaven National Laboratory - Previous six dimensional linac orbit calculations, 1 performed with a computer program that was designed to include space charge forces, sug- gested that there is a considerable transverse emittance growth in beams with a brightness* of 10 9 and higher. This appeared to be caused by non-linear space charge forces. Further calculations were aimed at giving a more specific explanation to results obtained earlier. The effects of transverse-transverse and transverse -longitu- dinal coupling through non-linear space charge forces were separated and the dependence of transverse emittance growth on the initial particle distribution and on the magnitude of strong-focusing flutter are examined. *Work performed under the auspices of the USAEC. X R. Chasman, Proceedings of the 1968 Proton Linear Accelerator Conference. BNL 50120 ( 0-5*0, P- 372. 2 Defined as B = 10 s I /§ -fl^E 2 , where I is the current in mA, ¥.tf is the normalized emittance in cm-rad. C13. Multigap Debunchers .* A. BENTON, Brookhaven National Laboratory - The performance of two and three gap debunchers was investigated by computing how well a straight line between the ordinate s +1 and -1 and of abscissa length n radians can be approximated by a two and three term harmonic series. What is desired is a series that will minimize the maximum deviations between the straight line and the series approximation to that line. The usual Fourier series, or least squares fit which is equivalent to it, does not satisfy this desider- atum. The series coefficients were obtained by means of a computer program written for the CDC-6600. For a two term series, the minimized maximum difference is O.OI7. A three term least squares fit gives a maximum difference of O.OO58; this is small enough for our pur- pose, so no calculations were done to minimize it. The calculations were repeated for a straight line of exten- sion h radians along the abscissa. The results are mini- mized maximum differences of 0.061+ and 0.01*+, for two and three term series respectively. *Work performed under the auspices of the USAEC. Cll.t Interaction of a Particle Beam with Superconduc - ting Wavegide of a Proton Accelerator . F. HELLER, H. HIRSCHMANN, C. PASS0W, E. SAUTER, D. SCHULZE, H. SIEFKES, Universitat Karlsruhe - The results of theoretical inves- tigations on the interaction of a high current beam with a superconducting cavity are discussed and compared with experimental results of a beam loading analog experiment. C12. Space -Charge Forces in a Linac Buncher . B. G. CHIDLEY AND G. E. LEE -WHITING, Atomic Energy of Canada Limited - Three-dimensional calculations have been car- ried out with a continuous -fluid model. The beam is considered to be sliced into a number of equal disks and numerical integration is used to follow the motion of their centers. "Particles" are studied by expanding their coordinates with respect to the disk centers as a power series (truncated after third-order terms) in the initial values of the transverse coordinates. Equations Cllv. Phase Stability Studies for the ING Linac . W. S. CHAPMAN, Chalk River Nuclear Laboratories - The ING linac was to have consisted of 9 Alvarez tanks operating at 268|- MHz, accelerating the beam from O.75 MeV to 105 MeV, followed by 323 coupled cavity tanks at 805 MHz taking the beam to the full 1000 MeV. The tolerable beam spill level for the whole accelerator was about 1 part in 10 4 of the accelerated beam. The fre- quency transition at 105 MeV meant that, with moderate tolerances in the accelerating fields, loss from phase stability could contribute to beam spill at this level. A digital computer method was used to trace the beam through the linac in the presence of time varying errors in the accelerating fields. The field tolerances re- quired to keep the loss from phase stability below the ■tolerable spill was calculated and an optimum law for the stable phase in the 805-MHz section was deduced. The tolerances have also been calculated for a control scheme in which the reference for the accelerating field phase is derived from the beam, rather than from a refer- ence line as is usually the case. C15- An Analysis of Travelling-Wave Prebuncher s. G. W. PETERSEN AND W.J. GALLAGHER, Applied Radiation - The use of single -gap cavity-type prebunchers to increase the capture fraction of the electron beam injected into a linac, as well as to improve the output energy spectrum, is well known. The use of a travelling -wave structure having a phase velocity corresponding to the gun voltage, as a hunching mechanism, is discussed in this report. The analysis includes the effect of space charge forces on both radial and longitudinal focusing. Experimental results are presented for beam currents up to twenty amperes. Cl6. Transverse Space-Charge Effects in Bunched Beams .* J . CIAUS , Brookhaven national Laboratory . - It is noted that in general transverse space-charge effects will cause the emittance of a bunched beam moving in a transport system to become modulated with the bunch frequency, even if the emit tance of the beam source is stationary in time. Long chan- nels and high brightnesses tend to aggravate the effect. We treat this cause of apparent and real blowup analytical- ly for periodic focusing systems conducting beams with small momentum spread. We find that the blowup may be minimized by choosing a focusing system of sufficient strength and by matching the beam emittance to its charac- teristics . Applying the same methods to nominally achro- matic dispersive systems, we find that transverse space- charge effects prevent exact momentum recombination for bunched beams. *Work performed under the auspices of the USAEC . C17 • Design of the Low Energy Beam Transport System of the BNL 200 MeV Injector Linac * R. CHASMAN AND T. J. M. SLUYTERS, Broo khaven National Laboratory - The distance between the 20C-MeV linac and the T5°-keV pre- injector is designed to be about 27 feet. A 200-mA beam r..ust be transported and bunched over this length without excessive loss in beam quality. To investigate the re- quirements of such a transport system numerical beam dy- namics calculations, taking into account the effects of space charge, have been performed. Non-linearities due to quadrupole fringing fields were also included in the computations. These have been shown earlier to have serious effects on the beam quality in a transport chan- nel. ] ) 2 In the present study an effort was made to minimize distortions introduced by fringing fields. This can be accomplished by a suitable choice of quadru- pole system, as predicted analytically. 3 Results obtained from calculations for different magnet schemes will be presented and the general layout of the transport system will be shown. Work performed under the auspices of the USAEC. 1 E. Regenstreif, Proceedings of the Los Alamos Linac Conference, October 1966, LA-36O9, p. 2k$. S P. W. Allison and R. R. Stevens, Proceedings of 1968 Froton Linear Accelerator Conference, BNL 5°120 (C-5U), P- 36^. 3 R. L. Gluckstern, Internal NAL Report FN-166 (1968). Cl8. Space Charge Effects in High Current Linear Electron Accelerator Transport Systems .* T. KHOE AND G. MAVROGENES, Argonne National Laboratory - Transverse and longitudinal space charge effects on short high cur- rent RF buckets of cylindrical geometry and uniform charge distribution are considered in free space. Two cases are examined: (a) The beam is radially constrained but free to expand longitudinally; (b) The beam is free to expand simultaneously radially and longitudinally. Attention was given to the energy spread in the RF buck- ets due to the space charge electrostatic field for both cases. The equations developed are relativistically corrected and readily applicable to practical beam prob- lems. A computer program was written to solve simul- taneously the differential equations of the radially and longitudinally expanding beam; the results are pre- sented in the form of curves giving the transverse and longitudinal expansion as well as the energy spread of different intensity beams as a function of drift distance. A solution to the problem of transverse expansion for a beam traveling in space with a nonsymmetrical conducting boundary (the vacuum chamber of a deflecting magnet) is presented. The simplifying assumptions are stated. ""Work performed under the auspices of the USAEC. C19- Particle Trajectory Perturbations in Beam Handling Systems . J. D0BS0H, Gulf General Atomic ; W. J. GALLAGHER, Applied Radiation Corporation - This report discusses three types of perturbations on parti- cle trajectories in beam handling systems due to space charge forces; the beam is assumed to be bunched, l) Owing to radial space charge forces, the beam will expand in diameter in field-free (or drift) spaces along the .beam orbit. 2) Owing to longitudinal space charge for- ces, energy dispersion will increase along the beam trajectory. 3) Particle trajectories of the inner and outer edges of a mono-energetic beam crossing a magnetic field are not similar. As a result there appears to be an energy dispersion in the beam. Mathematical analyses of these space charge effects and numerical calculations of their magnitude in several existing high-current linac s are given. C20. Design and Evaluation of Particle Beam Handling Systems . ANNUA GALEJS and PHILIP TRENT, High Voltage Engineering Corporation - We describe the procedures available, and in current use at HVE, for calculating beam-handling systems to various degrees of approxima- tion and exactness. With a self -optimization feature built into the ion-optics programs a first-order design is obtained subject to the boundary conditions imposed by the available space, by the specified target locations, and by the aperture restrictions of the available com- ponents . The optimization is most commonly applied to obtain a minimum beam cross -over, focused at a given location. It is generally applicable, however, to any desired number and type of parameters. An example of particular importance is the minimization of the differ- ence in flight time, including the effect of the momen- tum spread, during the design of isochronous systems for pulsed beam applications . Where it is desired or becomes necessary to evaluate the system quality in detail, the higher order effects are studied by exact ray tracing methods. From measured fringing fields, the aberrations are calculated in the individual components and the cumu- lative effect of these aberrations in a many-component system is derived. These techniques are illustrated by considering an example of a typical tandem post- acceleration beam handling system. C21.t Initial Performance of the AGS Slow External Beam .* L. N. BLUMBERG, M. Q. BARTON, G. W. BENNETT, J. D. FOX, H. C. H. HSIEH, R. J. NAWROCKY, AND A. V. SOUKAS, Brookhaven National Laboratory - Non- linear resonance extraction at v x = 8-2/3 has been achieved in the energy range 20-28 BeV at calculated 1 radial beam positions and settings of ejection magnets. Measured extraction efficiency of 70 to 80$ is near the theoretical ~ 85$. Septum scattering results in hori- zontal and vertical emittances about 2.5 times larger than predicted. The method used to turn off the rf results in a 1$ momentum spread which necessitates steering -magnet corrections in the external optics. Spill modulation from AGS magnet current ripple is con- trolled by feedback from spill monitors to the magnet voltage regulator and a signal from a backleg winding to an AGS quadrupole to modulate v x . Spill duration is ~U00 msec (limited by septum heating). The beam is time- shared with internal targeting experiments by alternate pulse operation. Work performed under the auspices of the USAEC. L M. Q. Barton, IEEE Trans, on Nucl. Sci., NS-lU, No. 660 (1967); M. Q. Barton and J. Faure, BNL Report AADD-131, (1967)- 3, C22 . Extraction and Transfer of High -Quality Beams from Synchrotrons of the FOOFDOD Type, with Application to the Omnitror. .* PHILIP F. MEADS, JR., Brobeck and Associates; FRANK B. SELPH, Lawrence Radiation Laboratory - Acceleration of ions of low charge -to -mass ratio in the Omnitron is accomplished in two or three acceleration cycles with the beam transferred between the synchrotron and the concentric storage ring between cycles. Suc- cess in such multiple acceleration requires that the beam quality be maintained through each ring-to-ring transfer. The extraction method here described provides a perfect ring-to-ring match in both betatron phase planes, including dispersion. Maximum efficiency is obtained from the deflecting magnets as a consequence of both kicking and extracting at the point of maximum radial betatron amplitude. The beam path and focusing are chosen to minimize the aberrations due to passing through the extreme fringing fields of the gradient magnets. This requires a special focusing magnet in the acceler- ator extraction line and the shimming of two storage ring gradient magnets. *Work supported by the USAEC. C23- Two -Turn Extraction from an Injector Synchrotron . A. VAN STEENBERGEN, Brookhavc-r. National laboratory* * - For a fast cycling synchrotron injector (booster), a sig- nificant cost reduction, mainly related to rf require- ments, may be obtained by reducing the bopster cycling rate. For this reason slow cycling synchrotrons with multiturn extraction have been considered for the purpose of a booster injector. The disadvantage of time depend- ent beam emittance and beam intensity during the extrac- tion process is well known. With two-turn extraction this problem can be avoided, making it still possible to reduce the booster cycling rate by a factor of two. Specifically for the 200-1+00 GeV NAL accelerator booster synchrotron, two-turn extraction has been studied and results are reported here , mainly related to extraction losses, betatron oscillation tune tolerance, and extrac- ted beam effective phase space dilution or beam transfer losses . *Work performed under the auspices of the USAEC **This work was predominantly done while on leave of absence at the National Accelerator Laboratory, Batavia, Illinois. C24 . The Effect of Momentum Spread in Slow Extraction at an Integer Resonance - A Theoretical Study . P.STROLIN AND E.J.N. WILSON, CERN, Geneva - The behavior of a beam with momentum spread undergoing extraction at an integer resonance has been studied with a simple analytic model and a more comprehensive computer program. It is shown that the stable and unstable fixed points can have an amplitude of oscillation about the unperturbed closed orbit that is comparable with the available radial aper- ture. This could lead to loss of the lower momenta be- fore extraction spill takes place and to a lower extrac- tion efficiency than that given by simple theory. These effects are discussed with particular reference to the CERN PS Slow Extraction. C25. An External Beam for the Cornell 2-GeV Electron Synchrotron .* A. BROWMAN, LOUIS N. HAND, G. ROUSE, AND T. TSO, Cornell University - Beam extraction has been achieved at the Cornell 2-GeV electron synchrotron by using independently controlled quadrupole and octupole magnets inserted in a straight section. The actual ex- traction is made with a pulsed septum magnet which avoids the problem of aberrations due to the synchrotron fringe field. Extraction takes place on 3-5 integral resonance in horizontal betatron oscillations. The oc- tupole field provides the non-linearity essential to efficient extraction. Characteristics of the beam are given. ■"Supported by National Science Foundation. C 26 . t Design of the 200-GeV Slow Extracted Beam at NAL . R. ANDREWS, A. KASCHKE, R. MOBLEY, AND C. RODE, National Accelerator Laboratory - The design criteria for the slow beam .are given, and the methods for achiev- ing high-extraction efficiency are discussed. C2T • Energy-Loss Extraction System with Thin-Septum Plunged Magnet at Kiinrod . A. G. A. M. ARMSTRONG, M. J. O'COHNELL, R. H. C. MORGAN, AND M. J. SHEEHAN, Rutherford Laboratory, England - Details are given of a system involving an energy-loss target, a plunged 1.0- cm septum magnet and correction of the Nimrod field where the beam emerges. A stationary radially focusing element is proposed, placed in the exit path of the beam, at a point soon after the beam has left the Nimrod mag- net. This element consists of a magnetic channel ener- gised partially from Nimrod fringe flux and partially from powered windings. The applied current has to be programmed with the magnet pulse to minimise disturbance of the accelerator field. Design work has so far been done with the program TRIM, solving the sections of the configuration in various azimuths as two dimensional prob- lems . The lip and targetting program LIMP has been used to generate "realistic" assemblies of, typically, 100 particles, which are then tracked through the extraction system using the program NIMDYN, which uses a detailed field model of the accelerator. A tagging facility enables particle identity to be retained through to the final statistics on assemblies of 100 particles or less. C28. Extraction from NIMROD Using the Two-Thirds Resonance . M. R. HAROLD, Rutherford Laboratory, England - In the design of a resonant extraction system for NIMROD, considerable attention has been given to the effects of using different methods of spilling the beam. It has been shown that for a finite circulating beam size, most spill methods result in a divergence spread at the septum magnet, which leads to an increased emittance from the machine. Another consequence of the beam size is that the proportion of protons hitting the septum will vary throughout the ejection period. The computer program NIMDYN has been used to study these effects, and to pre- dict all the features of the proposed system except that due to ripple. Two spill methods are found to have clear advantages, one being cheaper than the other but requir- ing a time-varying field in the septum magnet. C29. Lattice of the NAL 200-GeV Proton Synchrotron . A. A. GARREN, National Accelerator Laboratory - A brief description of the design adopted for the lattice of the 200-GeV accelerator to be constructed in Illinois is presented. The main features of this design are the following: capacity for acceleration to 200 GeV at 9 kG or U00 GeV at 18 kG; separated-function FOD0 standard cells; inclusion of six 50-meter-long straight sections; and relatively small circumference. Other designs studied were combined function F0F00B, and separated- function lattices with the quadrupoles grouped in doub- lets or triplets . C30. Lenses for High Energy Electron Beams . W. J. GALLAGHER, Applied Radiation Corporation - Use of the Glaser lens for axisymmetric focusing of electron beams is described; using a boundary value solution for the lens field and relativistic equations of motion. By this method lens aberrations appear as successive terms of the field solution. The effect of space charge forces on lens performance is discussed. Among electron micrp- scopists it is well-known that a requirement for construct- ing an ideal lense is that the axial field intensity di- minish radially. This condition, of course, cannot be met for a static field unless the field boundaries are superconducting. However, time varying fields possess this characteristic, and a cavity supporting the TE-01 mode is proposed as microwave lens, useful where beams have an rf microstructure. C31. Design of a High Energy Medical Linear Accelera - tor . H. HUBER AND H. LE30UTET, CSF - Corbeville - The main problem in the development of a high energy medical linac is to design a highly reliable beam transport sys- tem capable either of supplying an electron beam or pro- ducing" a photon beam of high quality at all energies, and this in all positions of the treatment head around the patient. The system we have used comprises: an achromatic 3-magnet system deflecting the beam by 37° , a 127 -deg sector magnet, with gradient and edge focusing, which has the particularly interesting property of being without dispersion, a quadrupole triplet giving a very small and circularly symmetric beam spot on the photon target. A set of servo systems and interlocks ensure automatic settings at each operation energy and make the machine fool proof and easy to operate by nonspecialized personnel. C32. The Application of Transient Beam Loading in Linear Accelerators to Obtain a Fixed Charge/Pulse . J. DOBSON AMD C.B. WILLIALiS, Gulf General Atomic Incor - porated - This paper describes a technique proposed as a fail-safe method of limiting the current in the electron mode of operation of medical linear accelerators. In the initial stage of transient beam loading of an electron linear accelerator, the decrease in energy with time is about linear. It will be shown that this phenomenon can be used to obtain a constant charge per pulse independent of accelerated beam current and peak beam energy when the accelerator is used in conjunction with an energy analyzing system and defining slits . The energy and the charge per pulse of the beam passing through the slits are independent of the accelerated current and peak beam energy, provided the slit energy bin lies on the linear part of the transient loading curve. Charge per pulse passing through the slits is directly proportional to slit width. The limitations of this technique and its application to various fields, including the electron beam therapy of malignant tumors and pulse radiolysis, will be discussed. C33. Proton Beam Cooling with Electrons in the Mon - Relativistic-Case . W. MAURER. Kernforschungszentrum Karlsruhe - The mechanism of collision damping for heavy particles is investigated in the nonrelativistic case. By means of the FOKKER -PLANCK coefficients the mean rates of change of momentum and energy for two kinds of particles and energy and temperature relaxation times are calculated. The energy changes in the various di- rections have been evaluated. It is possible to give a condition for beam cooling in the transversal directions. As an example, we have given the results for a proton- electron system. Calculations for relativistic particle energies are in progress. INVITED PAPER Dl . Prospects for High Duty Cycle Electron Linear Accelerators , J . E . LEISS , National Bureau of Standards - The two most serious limitations of electron linear accelerators as nuclear research tools are their relatively poor energy spectrum and their low duty cycle. Improvements in linear accelerator design, the possibility of race-track microtrons , s.nd progress toward CW superconducting linear accelerators indicate that these limitations of electron linear accelera- tors may soon he overcome. The research and accelerator possibilities which these new accelerator developments promise are discussed. D2.t The Astron Linear Accelerator . JACK W. BEAD, Lawrence Radiation Laboratory, Livermore - The Astron induction, electron accelerator has been redesigned and rebuilt to increase the beam energy and output current and to improve the quality and reliability of the out- put beam. The design beam parameters are: energy - k.2. MeV, current - 800 A, pulse width - 0.3 ^sec, momen- tum spread - 4$ FWKM, emittance - 25?r mr-cm. The accel- erator consists of an increasing-gradient gun with an oxide cathode and an output beam energy of 562 keV. The gun is followed by two constant -gradient injector sec- tions, each adding 220 keV to the beam energy. The remainder of the accelerator is made up of seventeen identical accelerator sections, each adding 190 keV to the beam energy. Solenoidal magnets are positioned between the accelerator sections to provide for beam focusing. Cosine -type steering magnets are placed so as to compensate for the earth ambient magnetic field and possible strong fields. Initial operating experi- ence with the new accelerator is described and results are presented. *Work performed under the auspices, of the UEAEC. D3 . t First Operation of the High Duty Cycle Saclay Electron Linac (A.L.S.) . G. AZAM AND H. LEBOUTET, CSF, Corbeville ; and F. NETTER AND C. TZARA, CEN de Saclay - Tests in CSF laboratories have given evidence for the excellent quality of the bunching in the first section. Tests on the site starting in January 1968 were performed during all the year. Operations with both electron and positron beams give many results, namely maximum electron energy 640 MeV with zero current and 5^0 MeV with 4-0-mA peak current and an energy distribution with FWHM 3 to 4/1000. The maximum peak current obtained was 60 mA; no beam break-up appears. Operations were performed at duty cycles of 1$ and 2$ with electron beam power of the order of 100 kW during many shifts of 30 hours; energy stability was better than 1$ for 30 hours. Special devices helping to handle the beam inside and outside the linac at such a power level are described. First measurements of e + /e~ conversion efficiency give an intensity ratio of positron beam relatively to electron beam, above 400 MeV positron energy, of the order of 5.10^*; improvements are expected. J)k . Dynamics of the Beam of Electrons in the A.L.S . G. AZAM, A. BENSUSSAN, H. LEBOUTET AND G. R0UX, CSF - Corbeville - The excellent quality of the bunching of the Saclay accelerator was indispensable in obtaining the expected performances . A low voltage injection was chosen, solution already selected by CSF for its previous constructions . Bunching is obtained by bunching cavity and a beam chopper between the gun and the cavity. The results obtained conform to those given by the program established by the computer. As regards the phenomena known as B.B.U., the A.L.S. sections were already in construction at the time when worldwide reports were being made about it. The first known results, extrapol- ated for the A.L.S. would have given a peak current lower than 10 mA at 10 [is , at its maximal limit , i.e. five times less than was required. The group velocity distribution of the sections was redesigned. Three types of sections were calculated in order to eliminate recurrence, by alternating sections of these three types along the machine. The results of the tests showed that this method was successful. D5 ■ Con verter and Positron A.cceleration on the A . L . S . Mme. J. AUCOUTURIER , H. LEBOUTET, G. AZAM AND C. FERRAU- DIN, CSF - Corbeville - Estimated performances are as follows: Positron beam: 500 MeV with peak current of 60 |iA, i.e. an average value of 0.6 jiA. These perform- ances take a principal electron beam of 30 kW on the converter target. The design of this target involves a watercooled moving part in vacuum, immersed in the mag- netic field of the converter. The complete system is described in this report. A report on the converter op- tic has already been published. The main results of the analysis of this publication are outlined here. An effi- ciency between positron and electron beam higher than 10 -3 was expected. The first results obtained on the accelerator were (in September 1968) : 5.10 -4 , i.e. very near the expected figure. More experiments are to be made before the end of this year. D6. D utch Proposal for 10$ Duty Factor, High Energy Electron Lina c, C. DE VRIES AID P. J. T. BRUINSMA, Institute for Nuclear Physics Research, Amsterdam - The Institute for Nuclear Physics Research expects a final decision by the Netherlands Government soon on a proposal for a 10$ duty factor, 250-MeV linear acceler- ator for electrons. The basic design of the 170-m machine is similar to those of the MIT and Saclay pro- jects. The radio-frequency power will be supplied by 13 klystrons (75 kW average rf power). It will be pos- sible to raise the energy to 500 MeV at lower duty factor (2.5$). The intensity and beam quality anticipated will accommodate electron scattering experiments as well as experiments with electro-produced mesons. D7. The 95 ~MeV Electron Linac at Ansterdam . P. J. T. BRUINSMA AND C. DE VRIES, Institute for Nuclear Research, Amsterdam - The Institute's 95 "MeV electron linac (EVA), now fully operational, will be described. At high energies and low currents 80$ of the current of the low-emittance beam falls within a 0.3$ energy-band. Maximum peak currents of up to 150 mA are obtained with- in a 0.8$ energy-band. This performance is attained with two SLAC sections (each 3 - m long), and a Frascati- type injector. The inherent properties of both are matched by the excellent performance of the peripheral equipment which includes two modulators for powering the two SLAC-type klystrons, the cooling system, the micro- wave driver, and interface instrumentation. D8.t Recent Beam Performance and Developments at SLAC * R. H. HELM, H. A. HOGG, R. F. K00NTZ, G. A. L0EW, R. H. MILLER, AND R. B. NEAL, Stanford Linear Accelerator Center - The purpose of this paper is to describe recent developments at SLAC which have contributed to improve- ments in beam operation. The first part summarizes overall beam performance and operational efficiency in delivering beams to various experiments. The second part describes specific developments, such as the achieve- ment of higher energies, increasingly narrow energy spactra, higher beam breakup current thresholds, chopped beams, and improvements in pulse-to-pulse operation. The discussion includes a description of various new pulsed devices such as pulsed quadrupoles, improvements in the positron source, and new beam-loading measure- ments obtained for very short pulses. *Work supported by the USAEC. D9. Kl;. i-. ron Performance at SLAC * JEAN V. LEBACQZ, Stanford Li.oaar Accelerator Center - The 250 high power klystrons used at SLAC provide an excellent opportunity for analysis of tube operating performance under well con- trolled conditions. The overall klystron protection sys- tem is reviewed, as well as the techniques used for accep- tance, installation, and maintenance of the high power SLAC klystrons . Statistical information obtained to date is analyzed to arrive at the probable klystron life as a function of operating parameters. Use of the information to determine the operating cost of the SLAC accelerator as a function of beam energy level is presented. SLAC is considering further increase in beam energy by increasing the klystron power output and operating voltage. The im- plication of such changes on machine operations are dis- cussed in light of life predictions obtained to date. *Work supported by the USAEC. D10. The Development of a 30-MW, 2856-MHz Klystron for Accelerator Service . F.G. HAM4ERSAND and J.R. T0M- CAVAGE, RCA - The RCA-8568, 21 -MM, permanent and elec- tromagnet focused klystron has been used for accelera- tor services which require 2.5 to 50-|is pulses of rf power at 2856 MHz. Now, due to increased peak rf power requirements at SLAC, a new RCA klystron, the Dev. Type A-lUOl, is being developed to provide peak rf power output in excess of 30 MW at a pulsed dc beam voltage of 270 kV. As far as possible, the AlUOl is be- ing designed to be interchangeable with the 8568. The increased tube power output capabilities are being achieved by improvements in the output window, the rf interaction structure, and the collector. Use of the All+01 in existing 8568 installations will require an increase in the high voltage modulator capabilities plus slight modifications in the operating position layout . Dll.t Performance of lUO-MeV High Current Short Pulse Linac at ORNL .* N. FERIKG, Varian Associates , and T.A. LEWIS Oak Ridge National Laboratory - High current results exceed- ing specifications of ll+0-KeV electron traveling -wave L-band linear accelerator are discussed. The 150-kV gridded gun injector has demonstrated pulse currents in excess of 30 A and pulse widths as narrow as 2.3 ns at 1000 pps . The ac- celerator wave guide sections are of nonuniform impedance design 1+.3 meters each and are driven by 2U-MW 67.5-kW L-band klystrons. Uniform solenoidal focusing is used over the accelerating sections and quadrupole focusing is used in beam transport. A short pulse current exceeding 16 A has been observed at the target position within an area of less than h cm 2 . D12. Standing Wave Operation of Electron Linear Acceler - ators . W. J. GALLAGHER, Applied Radiation Corporati on - Although periodic structures, when used as particle accel- erators, always involve a particle-wave interaction that can be analyzed as a traveling-wave interaction (TW), the actual mode of operation may be standing wave (SW) . In fact, most low energy accelerators are operated in this manner. Presentation of the analysis of SW operation is complicated because cryogenic (that is, superconducting with complete neglect of waveguide losses) or ambient oper- ation produce quite different results; furthermore, the location of power input feedpoints vary details . This re- port discusses ambient temperature SW operation. Results of the analysis of cryogenic operation are quoted for com- parison. D1 3 ■ Velocity Kodulation System for Enhancement of 50 Picosecond Fadiaiion Pu'Jse . N. J. S0RR1S AKD R. K. HANST, E. G. and G. - Intense radiation pulses, 50 pico- seconds in duration with peak intensity of 30 amperes have been attained at the EG&G/AEC Linear Accelerator. Individual micro-structure groups of electrons that nor- mally occur at the fundamental accelerating frequency have been isolated, as reported previously. 1 Increased intensity of these 50-ps radiation bursts is attained through the use of velocity-modulation bunching at the sixth subharmonie of the acceleration frequency. The calculated and experimental charge increase is compared and the system is described in detail. The charge has been measured as 1.5 nanocoulombs per burst, about 30A peak for the 5°~ps duration. Synchronization of the injector pulse to the rf acceleration frequency with a precision of 30 ps results in pulse to pulse reproduci- bility of a few percent and permits recurring pulse measurements to be made with sampling oscilloscopes. This short radiation burst, with increased intensity, allows the stimulation of scintillators and chemical systems to study their response in the subnanosecond time domain. Neutron time-of -flight measurements with a total resolution of UOO-5OO ps have also been demon- strated. J-Hanst, R. K., and Norris, N. J., IEEE Trans. Sci , KS-12 No. 3, 830-835 (1965). on Nucl. *Work performed under the auspices of the USAEC. INVITED PAPER D14. Resonantly Coupled Standing-Wave Accelerator Structures for Electron and Proton Linac Applications .* E.A. KNAPP, Los Alamos Scientific Laboratory - Theoretical and experimental studies on resonantly coupled accelerator structures for both proton linac and electron linac use are reviewed. The side-coupled linac structure, useful both for electron linac and high energy proton linac systems, will be described. The performance of a 25-KeV, 1-mA aver- age, 6% duty factor side-coupled electron linac at the Los Alamos Scientific Laboratory will be discussed. The post- coupled drift tube linac structure, developed at Los Alamos, and the multistem drift tube linac structure, developed at Brookhaven, will be discussed as examples of resonantly coupled low energy proton accelerator structures. *Work performed under the auspices of the USAEC . D15 • Resonant Frequencies and Mode Structures of an Alvarez Type Linac Cavity . M.J. LEE, R. CHASMAN, H. K. PETERSON, Brookhaven national Laboratory ; R. L. GLUCKSTERN, University of Massachusetts - Numerical calculations have been carried out to determine the effects of the non-uniformity of an Alvarez type drift tube linac cavity on the mode frequencies and average field flatness. This was done by following a method first used "by Walkinshaw et al 1 for a single -cell cavity and recently extended by Gluckstern 3 to multi-cell cavities. The object of the study is to obtain the fol- lowing information: l) mode structure and resonant fre- quencies of a cavity consisting of several identical cells, 2) mode structure of a cavity consisting of several cells with slowly varying geometrical parameters^ 3) sensitivity of the field flatness to dimensional errors for the zero and rr/2 modes. Results will be pre- sented and discussed. *Work performed under the auspices of the USAEC. 1 W. Walkinshaw. C. S. Sabel, and S. Outram, AERE t/m 101+ (195U). 2 See abstract Dl6 by R. L. Gluckstern. D16 . Method for Calculating Mode Structure and Field Flatness in an Alvarez Type Linac Cavity .*R. L. GLUCK- STERN, University of Massachusetts - The method of Walkinshaw et al., 1 has been extended to cavities con- sisting of drift -tube loaded cells with varying length to determine the field flatness and sensitivity to errors for the various modes of a realistic structure. Specifi- cally, one considers a cylindrical cavity with N cylindri- cal drift tubes of differing length, but same radius. The electric field in each gap is considered uniform in the axial direction. The field in the region between the drift tubes and the outer wall is expanded into Fourier coefficients linearly related to the N parameters representing the electric field in the N gaps, by the continuity of the axial electric field at the drift tube radius. One then equates the average magnetic field in each gap at the drift tube radius as calculated in the gap and exterior regions, obtaining N equations in N unknowns. The vanishing of the determinant yields the eigen-frequency and the relative solution for the N unknowns yields the field flatness. Computations with actual structures are now underway. *Work supported by the National Science Foundation. 1 W. Walkinshaw, C.S. Sobel and S. Outram, A.E.R.E. T/M 10>+ (195*0. INVITED PAPER D17. Proton Linear Accelerators .* G. W. WHEELER, Brookhaven National Laboratory - A new generation of proton linear accelerators is under construction. The new or improved techniques which will lead to major advances in the perform- ance of these linacs are discussed. These include brighter ion sources and columns, cavity field stabilization tech- niques, beam loading and space charge compensation. The status of some of these new linacs is briefly presented. *Work performed under the auspices of the USAEC . Dl8. Status of the RF System for the 200-MeV Linac Injector for the AGS .* J. KEANE, R. F. LANKSHEAR, J. F. SKEEHAK, AMD R. L. WITKOVER, Brookhaven National Labora - tory - The new 200-MeV Linac injector being built for the AGS conversion program will be powered by nine rf modules with a total rf power output of over 1+0 mega- watts. A prototype rf system has been built and operated for more than a year. The design features of the rf system include: modular construction for rapid replace- ment of defective units, solid state logic and control systems, a series passing tube used as a programmable capacitor bank charging and isolating element, and a floating-deck modulator using three magnetically focused triodes as the passing tubes and allowing linear control of the plate voltage of the 7835 triode final power amp- lifier. Grid drive for the 7835 is provided by a 350-kW driver unit, which also serves as the summing point for an rf phase control loop. Final design units are being procured. The design features and operating experience with the prototype system are discussed. *Work performed under the auspices of the USAEC. D19- Beam Eirdttance-Time Variation of the 50-MeV Proton Linear Accelerator of the Zero Gradient Synchro - tron .* MOHAMED E. ABDELAZIZ,** UAR Atomic Energy Estab - lishment, Cairo - One of the main problems considered in beam diagnostics of the 50-MeV proton linac of the Argonne ZGS was the measurement of the injected-beam emittance and density distribution in phase space. By scanning the beam with a fast strip electrode -and- slit combination with an angular resolution of O.35 mrad it was possible to watch time variations of beam emittance during the linac pulse. Use was made of a multiplexed A-D converter and a high speed buffering system linked to a control computer, thus sampling the beam 200 times during the beam pulse at a speed of l|is per sample . Emittance figures were obtained and ana- lyzed under different operating conditions of beam cur- rent, preinjector voltage, and quadrupole magnet cur- rent. These results are useful for future automatic computer-control of the linac beam during machine oper- ation to satisfy optimum working conditions of the ZGS injector. *Work performed under the auspices of the USAEC . **Visiting Scientist at AKL in 1967-1968. D20 . A Unique High Duty Factor Series Hard-Tube Modu - lator for Use in the Los Alamos Meson Physics Facility .* J. ROSS FAULKNER, Los Alamos Scientific Laboratory - The 200-MHz portion of the Los Alamos Meson Physics Facility (lAMPF) requires three pulsed xf power sources, each de- livering 3-MW peak power at lk.k% duty factor (120-Hz, 1200-^sec pulse). This rf energy must be controlled over s. dynamic range of about 30$ at a field amplitude toler- ance of + 1-5%' The control of this rf power will be ac- complished via a series hard-tube modulator. A modulator utilizing a pair of Eimac l+CW250,OOOA tetrodes in a rather unique screen-driven circuit has been constructed and test- ed at duty factors exceeding the required l^.Ufo. Plate voltages of up to !+0 kV have been switched into a short circuit without losing control of the modulator. Ampli- tude modulation of the pulse using both a step function and a sinusoid has been successful. The problems of modu- lator tube voltage hold-off and grid emission which led to the design of this unique circuit wil-l be discussed. *Work performed under the auspices of the USAEC . D21 - The BNL 50-MeV Linac RF Multiport System .* J. T. KEANE, B. DeVITO and A. J. McFERNEY, Brookhaven National Laboratory - A new high power rf system has been installed at the BNL 50-MeV linac to accelerate the higher beam intensities obtained from an improved preinjector. 1 A 75-mA, 80-jj,s linac output current pulse with a good energy spread is the design goal. Design considerations for this system for coupling power to the linac cavity via three ports are discussed. System layout and mechanical design features that provide flexibility in system operation and tuning are presented. Initial operating experience and results obtained to date are also discussed. *Work performed under the auspices of the U. Energy Commission. *To be published by Th. J. M. Sluyters. S . Atomic D22 . Microwave Instrumentation for Accelerator RF Systems . * R.A. JAMESON, W.J. HOFFERT AND D.I. MORRIS, Los Al amos Scien t ific Laboratory - In order to make de- tailed measurements of the rf amplifier-accelerator sys- tems for the Los Alamos Meson Physics Facility (LAMPF) proton accelerator, it was necessary to develop better directional couplers and slotted lines. The degree of precision required in the construction and adjustment of these devices when measurements of a few percent ac- curacy are desired in complicated, mismatched, high-power systems is surprising. The theoretical considerations and the mechanical refinements necessary to achieve good performance are outlined in this paper. The results of some recent measurements on the rf system are reviewed. *Work performed under the auspices of the USAEC. D23.t Recent Improvements to the Berkeley Hilac * R. MAIN J.M. HAUGHIAN, D. VORKOEPER, A.T. WATAIJAEE, T. HENDERSON AND E. CHUCK, Lawrence Radiation Laboratory - The Hilac prestrip per cavity has recently been lengthened to 20 feet, and now utilizes drift tubes containing tape-wound quadrupole mag- nets. A new injector terminal will operate at 800 kV. This combined system will be capable of accepting ions with charge-to-mass ratios as low as 0.095, thereby taking ad- vantage of increased source output at lower e/m ratios and providing greater transmittance through the cavity. The system is expected to produce a krypton beam approximately 500 times more intense than was possible with the old sys- tem. *Work performed under the auspices of the USAEC. D2U . Study on Interdigital H-Type Structure for Heavy-Ion Linear Accelerators . M. BRES , A. CHA- EERT, J.C. GAVET, D.T. TRAN, B. VEYR0N, G. V0ISIN, Institut de Physique Hucleaire, Universite de Lyon , France - Due to the very low heavy-ion velocity at injection, the frequency must also be kept low and the Alvarez and twin-line structures become ineffi- cient. Experimental work has been done at Lyon on new type structures well suited for low velocity range, namely the interdigital H-type structure. The dimensions of this type of structure as well as its electrical characteristics prove to be very attractive at low frequency; furthermore, due to the particular field pattern in these resonators, radial focusing of the beam appears to be possible with magnetic quadrupoles at energy as low as 50 to 60 keV/nucleon and frequency in the range of 20 to 30 MHz. Such a field pattern also gives good acceptance for the whole cavity. This paper presents our last results, discusses various prob- lems, and gives the main parameters of Lyon's 10 MeV/nucleon heavy-ion linear accelerator project. D26. Transit Time Factors and Field Magnification Fac- tors in Ion Linac Ga'ns . D. 0. B0EHNE, University of Hei - Field measurements in gaps of dif- delberg, West Germany ferent widths have been performed in the electrolytic tank and in a magnetic gap model. From these data the transit time factors and field magnification factors are derived and compared to existing information obtained by MESSYMESH field calculations and analytical approximations . D27 . RF System Development for the Heavy Ion Linac . B. STADIER, Unilac Group, University of Heidelberg, West G ermany - The layout of the new radio frequency system for a variable -energy variable-mass heavy ion linear ac- celerator is described. Results from specially designed VHF amplifier for variable power output as well as for the phase and amplitude control system are shown. D28. Linac Cavity Technology . D. B0EHNE, UNILAC -Group , " Heidelberg - Both rf and outgasing properties of model cavities are reported. Electro formed, vacuum-cast, and ordinary copper sheet metal are compared with different electroplated mild steel samples. For the electroformed and electroplated full scale cavities the mechanical design is described. Results on vacuum pump down, metal gasket application, and performance of drive loops and tuning slugs are presented. An Inexpensive Method of Cooling an RF Cavity .* ~.M. HAUGHIAK, Lawrence Radiation laboratory D29. R. MAIN AND A cylindrical rf cavity is cooled by water through extruded cooling tubes fastened to During installation, these tubes are heated tightly in place. This paper discusses the tube's cross section and spacing, method of clamping, end connections, and conducting f it and the tank's wall circulated the outside wall, and clamped details of the elongation and iller between *Work performed under the auspices of the USAEC. D25. A New Structure for Heavy Ion. Linacs . J. P0TTIER, CER de Saclay, France - This structure' uses an essentially T.E. field instead of a T.M. one like in an Alvarez linear accelerator. The drift tubes are alternately connected to conducting plates fastened to the wave guide, so that the device operates on airmode. The shunt impedance is roughly proportional to /3 "2 , so that this structure is convenient for injectors or heavy-ion accelerators. This shunt impedance is much higher than for an Alvarez struc- ture for energies lower than about 20 MeV/r.ucleon in the case of a small diameter of drift tubes (grid focusing), and lower than a few MeV/nucleons in the case of larger diameters (strong focusing). The wavelengths to be used are about five times greater than in an Alvarez, so that the defocusing forces are about one fifth, and focusing is easier. For a given acceleration, such a machine, using amnode, can be about one half the length of an Alvarez. A model accelerating deuterons from 50 keV to 350 keV has been built and operates properly. INVITED PAPER El. General Design Features of the Indiana University 200-MeV Cyclotron .* M.E. RICKEY, M.B. SAMPSON AND B.M. BAR- DIN, Indiana University - A multiple -stage four-sector separated magnet isochronous cyclotron is presently under con- struction at Indiana University. Ions are to be accelerated by potential drop before injection into the cyclotron stages permitting operation with 1 < v z < 1.5 • The large flutter required for this axial strength increases the non- relativistic radial focusing frequency so that vr > l-l- The vr = V3 intrinsic radial quadratic resonance is encoun- tered at B = 0.^3 (100 MeV protons, 300 MeV 3 He) but extensive studies indicate that beam deterioration and loss are negligible with the chosen operating parameters . Fourth and higher harmonics of the orbital frequency are to be used for acceleration. A charge -to -mass ratio range of l/6 < q/M < 1 is planned; this, together with the external ion source, median plane injection, strong focusing and large dimensions, provides an excellent heavy ion capability. A maximum design energy of 200 MeV is planned for protons; maximum energies for other ions are given by E = 2^-0 q 2 /M MeV. A dee-in-valley design with the very large axial aperture inherent in this facility has many advantages . Among these are the narrow magnet gap, capacitive tuning of the dees, dee voltage increasing with radius, and structural simpli- fications . It also permits sufficient additional vertical aperture inside the dees for second harmonic rf electrodes permitting asymmetrical square-waving of the energy gain per turn versus rf phase. Use of the fundamental and second harmonics of proper relative amplitudes and phases can provide a uniformity 2:1000 over a 50° phase interval and 1:10000 over a 25° interval. A small additional third harmonic component can double these intervals. *Work supported in part by the National Science Foundation. INVITED PAPER E2. Synchrocyclotron Improvement Programs .* HENRY G. BL0SSER, Michigan State University - Increasingly the signi- ficant experiments in the energy range of the synchrocyclotron demand higher intensity and duty cycle. Mindful of this, and of the approaching operational status of high intensity facilities at Los Alamos and Zurich, the several labora- tories with plans for continuing synchrocyclotron programs have in progress or under study improvement programs for increasing the intensity and duty cycle of their accelerators. The principal revisions contemplated include: (a) new rf systems to provide higher dee voltage and increased cycling rate, with details carefully matched to requirements for maximizing the accelerated particle flux, (b) new central region designs utilizing hooded arc sources and electric and magnetic fields shaped for maximum focusing, (c) spiral ridge magnet pole tips to reduce the range of frequency modu- lation and strengthen focusing, and (d) redesigned extraction systems which in combination with the improved emittance characteristics of the new central region will lead to much higher extraction efficiencies than in the past. The principal features of these revisions are reviewed with comments on the particular configurations contemplated by several typical major laboratories . *Work supported in part by the National Science Foundation. E3.t Magnetic Field Tolerances for the TRIUMF 500-MeV H~ Cyclotron . M.K. CRADDOCK AND J. REGINALD RICHARDSON,* University of British Columbia - The mass of steel in the TRIUMF magnet will be in excess of 3000 tons. In designing this magnet it has been found that there is considerable interplay between manufacturing methods and their tolerances on the one hand, and the tolerances required by beam dynamics on the other. Probably the most significant tolerance in its effect on manufacturing methods is that relating to the spiral shape of the magnet sectors. The precision required in this case will necessitate an extensive shimming program on the steel shape subsequent to manufacture . The need for axial focusing also sets limits on the variation in magnetic flutter and will have an important effect on the extent of the program to measure the magnetic field. The accuracy required for the measurement and rectification of the radial field gradient is determined by the re- quirement of isochronism, as is the number and arrange- ment of trim coils. Since the magnet is essentially composed of six separate sectors, the avoidance of a first harmonic sets some unusual limits on the posi- tioning and uniformity of the sectors. The requirements of separated-turn acceleration are also considered. *0n leave from UCLA. E^.t JINR Synchrocyclotron Modernization Design . V.P. DMITRIEVSKY, Joint Institute of Nuclear Research, Dubna E5-t Nevis Synchrocyclotron Conversion Project .* R. COHEN, E. MARTIN, J. RAINWATER, R. SCHNEIDER AND K. ZIEGLER**, Columbia University , and S. OHNUMA, Yale University - The Nevis Synchrocyclotron is to be con- verted from a 390-MeV machine with an internal beam cur- rent of 1.6 p,A and no external beam to one whose energy will be ~ 550 MeV. The internal beam current will be more than 20 ^A and the external more than 5 (xA. The average magnetic field will rise with radius - 17.2 kG at the center to a maximum near 20 kG at 80 inches - to reduce the rf frequency swing and to increase maximum (BR) for a given yoke flux. The beam will be focused by a set of 3-fold spiral iron shims having a median plane gap of 1 inch near the center of the machine and 5 to 6 inches at the largest radii. Because of the small cen- tral median plane gap, one set of shims will be at the rf potential and will have to be supported on insulators . Using measured fields of model magnets in computer codes, we find that the beam is vertically well focused at all radii. In particular, at the critical region near 10 cm where the effect of space charge is most serious, values of v z > 0.3 have been achieved. ♦Supported in part by the National Science Foundation. ** On leave from the University of Heidelberg, Germany. Eo. Electric Focusing at the Center of a Cyclotron .* R. COHEN AND J. RAINWATER, Columbia University - Usual calculations of the vertical focusing due to the dee voltage at small orbit radii involve approximations that are poorest for the first few turns where this electric focusing term is most important to compensate for the weak magnetic contribution. Two symmetric dees are con- sidered and an infinite trajectory perpendicular to the dee mouth is treated, to obtain the net vertical impulse. We treat the impulse for each half gap separately, so that alternate gradient terms are not automatically averaged to zero. In a second independent method, a uniform vertical magnetic field was included, and both electric and magnetic forces were treated with a numeri- cal integration of the equations of motion for a half turn. The proton momentum is initially parallel to the gap and to the median plane, with initial Z=0.^ times the full dee height, and (simulated) space charge repulsion force proportional to Z is added. This yields the effec- tive contribution to v z 2 to oppose vertical space charge repulsion when space charge and focusing terms cancel in their effect on P z over a half turn. ♦Supported in part by the National Science Foundation. ET • N evis Synch r ocyclotron Conversion Program - RF System .* R. SCHNEIDER AND J. RAINWATER, Columbia Uni - versity - The proposed three -fold symmetric and radially increasing magnetic field requires the accelerating rf field to cover the frequency band from about 27 MHz to 18 MHz. The peak dee voltage will be between 30 and 50 kV, with the riiaximum near injection. The repetition rate will be > 300 per second, with the rf turned on for hCffo of the time. The (single) dee structure will be 170 inches wide and between one-quarter and one-half a wave- length long. One of the three pairs of sector-iron shims will be incorporated in the dee and supported on BeO in- sulators . For the presently favored design, tuning will be accomplished by two rotating capacitors with axes directed toward the center of the magnet. Each rotor will have three layers of 12 blades each . The stator blades will be coupled to six transmission lines, which will run to the dee. The rotors will operate near rf ground potential. This design permits effective mag- netic shielding of the rotor to minimize eddy current losses. Excitation of the dee will be provided by two grounded-grid, triode oscillators cross-coupled to quarter-wave stubs on the two sides of the dee. ♦Supported in part by the National Science Foundation. E8 . Extraction from the Modified Nevis Synchro - cyclotron .'- R. COHEN, E. MARTIN, K. ZIEGLER,** Columb i a Universit y, and S. OHNUMA, Yale University - Our extraction studies indicate that we get the larg- est turn separation using a peeler-regenerator for the excitation of the radial oscillations. We also intend to use an additional time varying magnetic bump to increase the duty factor of the machine. This bump will be used to keep the beam away from peeler -regenerator during the acceleration cycle. After reaching the final energy the radio frequency will be cut off, and the time varying bump decreased slowly, thus moving the beam into the extraction sys- tem. This concept of the extraction system has been investigated using an orbit tracing program, which includes radial and axial motion as well as the coup- ling from radial to axial motion. The results indi- cate that we can expect a turn separation of the order of 1 in. at an azimuth where the mouth of a magnetic channel has to be inserted. If as expected, we have a turn separation of the order of 1 in. at the en- trance of the extraction channel, then a channel which drops the field by h kG over a distance of 20 in. would be sufficient to lead the beam out of the accelerator. Because of space limitations (the ver- tical aperture at the extraction radius is only 6 in.) it will probably be necessary to use a square coaxial current channel with compensating iron shims. "Work supported in part by the National Science Foundation . **0n leave from the University of Heidelberg, Germany. E9 . t The University of Maryland Isochronous Cyclo - tron . R.E. BERG, J.F. BRIDGES, K.D. JENKINS, H. KIM, M. REISER, T. ZINNEMAN, University of Maryland ; T.H. JOHNSON, W.H. WHITE, Raytheon Company ; P. DELPHIN, F. DUPONT, A. DUPUIS, R. JEAN, R. IACAZE, K. LEBOUT- ET, Compagnie Generale de T.S.F, Paris - Design fea- tures of the University of Maryland Isochronous Cy- clotron are discussed and a description of initial turn -on and operation is given. The four-sector magnetic field was designed with the aid of a one- third scale model magnet utilizing both the experi- ence with the Grenoble cyclotron and computer studies at the University of Maryland. The original maxi- mum design energy was increased to ll+O MeV protons by modification of the spiral angle after full-scale magnet measurements . The dual rf amplifier chain (250 mW to 250 kW per channel) drives two dees in- dependently in both push-pull and push-push modes over a frequency range of 10-22 MHz from 20 to 90 kV. E10. Design of the Beam Transport System for the Uni- versity of Maryland Cyclotron . R. E. BERG, Unive rsity of Mar yland - The University of Maryland cyclotron will ac- celerate protons up to about 1^5 MeV, alpha particles up to about 190 MeV, and a variety of other nuclear projec- tiles to corresponding energies. The experiment space is on two levels, separated 25 ft vertically. Each area is subdivided into isolated experiment vaults . Five beam lines are provided in the lower area; beam switching and energy analysis of up to AE/E = . 06%/mm FWHM will be ob- tained with a 1+0-in. dia, n=0 circular pole magnet. Ver- tical translation of the beam to the upper area will be obtained by two 60-in. n=0 double-focusing magnets which will also provide energy resolution up to AE/E = 0.012%/ mm FWHM. With quadrupoles , it will be possible to oper- ate this magnet system in any of three modes: l) doubly dispersive, 2) singly achromatic, 3) doubly achromatic. Beam switching in the upper area to any of six beam lines will be provided by a second lt0-in. circular magnet. Design considerations are given, and problems discussed. It is envisaged that the beam transport system will be operational by January 19&9, an 1. It is composed of an electrostatic deflector, positioned in a hill sector, two totally screening compensated iron chan- nels 3 in the following valley, and an extraction channel in the fringing field of the next hill. At 90 kv/cm the deflector provides a turn separation of 3 cm at the en- trance of the compensated channels. The septum is an 0.02-cm tungsten foil combined with some carbon plates. The disturbance of the internal beam caused by the chan- nels 2 was measured to be negligible because of an active compensation, indicated by a gradient probe. The extrac- tion channel with an electrostatic deflector inside the iron channel matches the specified position, angle, and acceptance of the beam transport system. The radial emittance of the extracted beam guaranteed to be <20 mia- mrad; the axial emittance <25 mm-mrad. Measurements are being performed for d . The energy resolution, yet to be measured, should be <3 X 1CT 3 FWHM. External currents should be >10 pA for p, a, He§ + and >20 jxA for d, the reached values are given. Precessional extraction giv- ing external currents >^0 pA has been tested at 60-MeV d . 3 1 U. Schmidt-Rohr, IEEE Transaction on Nucl. Sci. 13, ^38 (1966). 2 R. W. Muller, B. Berkes , Nucl. Inst. Meth. 1*1, 151 (1966). 3 H. Thimmel, Communication on the Fifth European Cyclotron Progress Meeting. E19- T he k MeV Separated -Orbit Cyclotron .* J. A. MARTIN, L. N. HOWELL, E. D. HUDSON, R. S. LIVINGSTON, J. E. MANN, S. W. M0SK0, E. G. RICHARDSON, JR., R. E. WORSHAM, H. F. ZIEGLER, Oak Ridge National Laboratory - Fabrica- tion and installation of components of the Separated- Orbit Cyclotron Experiment (SOCE) are nearly complete. The SOCE will provide a unique facility for the evalu- ation of an operating SOC system to extend and comple- ment earlier theoretical and experimental studies. The six -sector four -turn accelerator will provide maximum energies of k MeV for protons and deuterons and 8 MeV for 3ne2 + and ^He2+ ions. . The energy can easily be varied over a 3:1 range. Proton currents in the 10-to-20 mA range are predicted. Ions are injected into the SOC at one-quarter the final energy. The injection system con- sists of a duoplasmatron ion source and a 500-kV dc accelerator, followed by a three-cavity linear accelera- tor. Excitation tests have been completed on each cavity with its respective power amplifier. A magnetic field survey has been completed for one magnet sector and the results extrapolated to the other sectors. Trimming coils on each pole tip provide for final field adjust- ments. Injector testing is under way; initial operation of the complete machine is scheduled for early spring of 1969. *Re search supported by the USAEC. E20 . Test Results from Coaxial Cavities for Separated Orbit Cyclotrons .* N. F. ZIEGLER, Oak Ridge National Laboratory - Three different accelerating cavities were tested at ORNL for possible use in separated orbit cy- clotrons (SOC). All cavities were operated at about ^9-2 MHz and at, or above, design power levels. The largest of these cavities is a prototype for a 10 to 50-MeV proton SOC having a total of 15 beam holes and a maximum accelerating voltage of about 290 kilovolts. In cross-section, the prototype is a wedge-shaped coaxial line. Its overall width is about 230 in.; its height, 82 in.; and the maximum thickness, 67 in. Four tuners are located in the top of the cavity opposite the open end of the center stub for adjusting the cavity frequency and voltage distribution. The cavity was operated at various power levels up to a maximum of 66 kilowatts. At this power input the X -radiation near the cavity increased markedly with increasing power input . Some difficulty was encountered with multipacting, but the problem diminished steadily with operating time. The other two cavities tested are being used in the Separated Orbit Cyclotron Experiment (SCCE). One of the cavities is for use in the cyclotron and the other in the injec- tor. Both cavities were operated under vacuum and at power levels in excess of that required. *Re search supported by the USAEC under contract with Union Carbide Corporation. E21. Unique Mechanical Fabrication Techniques on the Erookhaven National Laboratory Cyclotron . * R.J. McCRAC- KEN,** C.P. BAKER, J. MANN, J. HESSINGER, E rookhaven National laboratory - Described in detail are some new and different coil and liner fabrication, testing, and assembly techniques. The profile coils are different in that they are of only one layer and are placed in preci- sion milled slots in the liner such that the centroid of the coil is located over the magnetic center of the ma- chine preventing the introduction of the first harmonic. Liner and coil fabrication techniques are discussed. All mechanical movement of the machine is hydraulically actuated including the clamping of the cantilevered dee. Specific applications of hydraulics to accelerators in general are discussed. "Work sponsored by the USAEC. **Now at Indiana University. E22 . Improvements in the Michigan State Universit y Cycl otron F.F System .* WILLIAM P. JOHNSON, Michigan St! University - A new dee voltage amplitude regulator has been built and should lead to a factor of two iisprovoi •.:.'. in the energy resolution of the MSU cyclotron. The rf drive to the final amplifier is regulated at low levels via an FET tetrode amplifier. The gain of the FET is controlled by a signal proportional to the difference between a reference voltage and a voltage ccrre store in.j to the sum of the two dee voltages. Protective circuits are included which remove rf drive to the final amplifier in the event of severe sparking in the dee cavity. Peak- to-peak noise levels on the dee voltage of less than 0.07$ are achieved and with careful adjustments noise levels of less than 0.05% have been obtained. Since the cyclotron is usually operated with internal beam pulse- widths of less than 0.7 ns, corresponding to an energy spread due to phase width alone of 0.07$, noise on the dee voltage makes a significant contribution to the over-all energy resolution of the external beam. ■"Work supported in part by the National Science Foundatir E2U . A Low Power Magnetic Channel with Pinole Compen- sation .* T. KHOE, R. BENAROYA, J. J. LIVIKG00D, W. J. RAMLER, AND W. WESOLCWSKI, Argonne Katioral La boratory - A magnet channel capable of guiding deflected 6C-MeV protons through the fringing field of an AVF cyclotron without perturbing inner orbits, has been tested in a 0.i)--scale model. The full scale channel will be com- posed of a 1010 steel cylindrical shell 3. 00 in. 0D, 1.18 in. ID, and 10 in. long with an external dipole winding extending to 5-92 in.OD. The dipole coil is approximated by dividing the winding into 16 sections, with centers 22.5° apart, and by making Ng = N Q cos 8 , where N is the number of turns in a section and 9 is the altitude angle of the center of a section. Scaling the model measurements to full size, the power is lU kW with 3/8-in. square 0D and l/8-in. round ID water-cooled copper conductors at 330 A, and the field halfway inside the channel is reduced from 7000 to 90 G, with a 20 G/in. gradient across the ID on the median plane. As close as 5 in. from the channel's edge, the first harmonic intro- duced is 1.1 G. Without dipole current, the field in the channel is 1560 G with a 16.2-G first harmonic at the same distance. *Work performed under the auspices of the USAEC. E25 . Magnetic Extraction Channel for the 30-Inch AVF Cyclotron . GEORGE 0. HENDRY AND JAMES L. TOM, The Cyclo - tron Corporation - An internally mounted magnetic channel is used to provide optimum external beam quality in a 15-MeV cyclotron. This magnetic channel is formed of several sections and placed after the electrostatic de- flector. The sections of the channel are designed to provide sufficiently strong horizontal focusing to com- pensate for the normally horizontal defocusing forces generated by the cyclotron fringe field. The horizontal focusing is generated by causing a uniform gradient re- versal in the fringe field. This field change is also designed to provide the best beam emittance at the cyclo- tron exit port . Various channel section profiles were studied and the resultant channel geometry and field gradients are presented. The compensating channel sec- tion gradients were optimized by a linear programming method known as computer code l+P as described by Meads - 1 An integral part of this program involves setting realiz- able constraints on the channel sections, such as maxi- mum possible gradients and acceptable phase widths and divergences. The resultant beam quality for such a chan- nel was measured by observing the phase space of the ex- ternal beam; the results are presented. 1 Nuclear Instruments & Methods, Vol. 1+0 (1966) , No. 1 E23. Ion Phase Measuring Equipment of the Relativistic Is ochronous Cyclotron at JUlich . H. EYBER and E. BITTEL, AEG -Tele funken - For the relativistic Isochronous Cyclo- trons of AEG with variable energy, an ion phase measuring device has been developed and applied for the first time to the JUlich Cyclotron. This method allows adjustment, control and optimizing of the time-plaice (phase position) of the ion bunch during the acceleration process (main- taining of the resonance condition by correct selection of frequency, of the magnetic main field, and the correc- tion field). It is non-disturbing (non-reactive) and operates as follows: On 12 radii of an azimuth measur- ing probes are mounted, gathering by capacitive coupling signals from the ion beam. By means of frequency trans- position, these signals are transformed by pulse sampling into a low-frequency spectrum. The result is a perfect display on a remote monitor, the X-def lection of which originates from the acceleration voltage. Due to the high cutoff frequency (about 5 GHz) the device also gives a correct distribution of the ion bunch. Thus, for ex- ample, effects from high-frequency voltage and ion source parameters may be indicated. E26. Beam Loss Due to the v r - v 7 = 1 and the 3v~ - v? = 3 R esonances .* M. L. MALL0RY AMD J. A. MARTIN, Oak Rid^e n ational Laboratory - In the Oak Ridge Isochronous Cyclotron (0RIC) there has been unexplained loss of proton beam near the maximum radius at the highest ener- gies. Recent successes in computing the trim-coil cur- rents have assured that the magnetic field is sufficiently isochronous and have permitted confident comparison of computed orbit properties with observed beam behavior. A study of computed orbit properties for high energy proton acceleration suggests that the beam is passing through the v r - v z = 1 resonance. The computed and measured radii for beam loss are in excellent agreement. The computed orbit data suggest the beam is also passing through, and in some cases closely following, the essen- tial resonance 3v r - v z = 3. In this latter case it has proved very difficult to accelerate the beam to full radius. It is anticipated that proper adjustment of the valley coils (which can vary the vertical focusing strength over a wide range) will avoid these coupling resonances, or will enable the beam to pass through them rapidly. "Research sponsored by the USAEC under contract with Union Carbide Corporation. E27 • Meson Channel Design for the SREL Synchrocyclo - tron . H. 0. FUHSTEN AND R. T. SIEGEL, College of William and Mary* - A pion -muon channel has been designed for internally generated mesons from the NASA Space Radiation Effects Laboratory 600-MeV synchrocyclotron. The channel, similar to these at CERN and Chicago, consists of three sections: a main section with 2k identical 11-in. bore quadrupole magnets, an input matching section consisting of a quadrupole doublet for matching to the meson emit- tance from the cyclotron, and an output section consist- ing of a bending magnet followed by a horizontally focus- sing 11-in. bore quadrupole. Computer programs using quadrupole transfer matrices including linear magnetic fringe field effects have been used to optimize the meson flux. The main section quadrupoles have terraced pole tips 1 and achieve a gradient of 2.1+ kG/in. Movable chan- nel mounting has been incorporated with pillar shielding to facilitate reorientation of the channel with respect to the cyclotron to change mean pion momentum entering channel. *Work supported by NASA. 1 G. T. Danby, J. W. Jackson; IEEE Transactions on Nuclear Science, NS-1>+, No. 3, P. 1*11+ . E28. Design of Stopped Muon Channels . S. OHMUMA, Yale University - A number of problems in the design of stopped muon channels for a meson factory have been studied using a new computer program. Compared with the existing program developed at CERH, 1 the new program has the following additional features: a) the polarization of muons can be calculated, b) all outcoming muons are included even when their "parent" pions are lost in the channel. Two suggestions, one by M. Jacobson and the other by L. Lederman, have been carefully investigated to see if they offer substantial advantage over the existing channels. Jacobson' s idea is to use a wedge- shaped degrader for reducing the pion energy spread. Lederman' s channel would collect low-energy muons pro- duced near the target instead of those produced by decay- in-flight of pions within the channel. This work has been done in close collaboration with H. Vogel of Los Alamos Scientific Laboratory. J-A. Citron, J. Fronteau,- and J. Hornsby, CERN 63-3O, (1963). F1 • t NAL Booster and Storage Ring RF Systems . J .A . DINKEL, Q.A. KERNS, L.A. KLAISNER, AIID G.S. TOOL, National Accelerator Laborator y - The NAL booster- accelerator radio-frequency system design is described in detail. This rapid-cycling system is ferrite tuned from 30 MHz to 53 MHz. Each high-power module has an rf-output rating of 100 kW provided by a cascode ampli- fier which is a removable part of the cavity assembly. Ferrite power dissipation is minimized by adjusting the rf voltage to that required by the beam's momentum spread and using a second harmonic guide-field compon- ent to shape the rf -voltage envelope. Ferrite ring size has been reduced to eight inches o.d. by using a number of parallel tuning stems in the lUO-deg drift- tube cavities . The low-level portion of the system corrects for both systematic and nonsystematic tracking errors using a single set of wide-band beam sensors, provisions are included for controlling the shape of longitudinal phase space for matching into the main ring and for adjusting the phase of the booster bunches relative to the stationary main ring buckets before transfer. In the design of a storage ring rf system, the control of the beam-cavity interaction is a basic problem. This paper describes an arrangement of TEM mode cavity, cascode power amplifier, beam pickup and feedback control loop to achieve a cavity-gap impedance of about 10 ohms over a frequency range from the syn- chrotron oscillation frequency (a few Hz) to the higher harmonics of the bunch frequency. The design center radiofrequency is 53-1 MHz. F2.t Electronic Systems of the 70-GeV Proton Synchrotron . S.M. RUBCHINSKY, Radiotechnical Institute of the USSR Academy of Sciences , Moscow. F3 • t Calculated Beam -Loading Effects in the HAL Main Ring RF System . G . REES , national Accelerator Laboratory The synchronous transfer of beam from the booster into the HAL ir.ain ring results in a partial turn of beam cir- culating in the main ring. This situation presents larj-e step changes in beam-loading to the main ring rf systen which must be handled by the cavity voltage regulation circuit. The behavior of the main ring rf system under these conditions has been studied with the aid of the Continuous System Modeling Program (CSMP). This program provides an analysis of system behavior starting with a system block diagram and a description of the driving functions. Nonlinear elements and functions may be in- cluded. This paper describes the rf system under study and the response predicted by the program to a variety of beam-loading conditions. The block diagram computer analysis technique is discussed and use of the CSMP pro- gram is described. ^•'f A Dielectric -Loaded Slow V.'ave Structure for Sep - aration of Relativistic Particles .* CHRISTOPHER T.M. CHANG, JOHN W. DAWSON, AND ROBERT L. KUSTOM, Argonne Nat ional Laboratory - A dielectric-loaded structure in which the phase velocity of the propagating electromag- netic fields is less than the speed of light is proposed for use as a traveling wave particle separator. The structure supports propagating modes which have suitable transverse deflecting fields and which have frequency, phase velocity characteristic (dispersion relation) which allows the device to be operated at different momenta by changing the frequency. Typical operating frequencies lie in the range of 1 to 5 GHz depending on the momentum range of the particles. A description of propagating modes with suitable deflecting fields and other degen- erate modes is given. The means of excitation, power requirements, dielectric losses, and efficiency of the structure are also discussed. Results of experimental work which support the validity of the description of the fields and modes are presented. In addition, some computer results on beam dynamics within the structure are discussed. From these considerations it appears that a practical device providing reasonable aperture could be built with suitable low loss dielectric and available klystrons. *Work performed under the auspices of the USAEC. F5- Long-Pulse Radio Frequency Separator Test Facil - ity .* JOHN W. DAWSON, ALFRED MORETTI, AND JOSEPH J. PEERSON, Argonne National Laboratory - A long -pulse line-type modulator has been designed to operate either one or two SLAC klystrons from a common pulse transformer. The modulator is capable of driving two klystrons to a peak power of 80 MW, 25O kW average for 55 microsecond pulses or one klystron to a peak power of itO MW, 125 kW average. The klystrons are driven from the same pulse transformer to reduce phase differences of the outputs of the klystrons. The modulator consists of two 50- microsecond pulse -forming networks which can be operated individually to drive a single klystron, or in parallel to drive two klystrons. The pulse network can be charged to 50 kV through a charging inductor from a 25 -kV, 10-A dc supply. The charged network is switched to the pulse transformer by a 50~kV hydrogen thyratron. The paper will present details of the modulator together with test results on the operation of the SLAC klystron at long- pulse, high peak power. Preliminary tests of the SLAC klystron have shown a capability of 10 MW for 55 |j,s with no damage to the tube . *Work performed under the auspices of the USAEC. F6 . Improvement in the RF Capture by Using ??3nsinu - soidal Accelerating Voltages . T. BERTUCCIO, M. ISAILA, J. KIRCHGESSKER, F. LARSEK, A. PASSNER, AND K. PRELEC, Princeton -Pennsylvania Accelerator - To improve the RF capture in PPA, experiments have been made with higher harmonic terms added to the accelerating voltage. Al- though the idea has been known for some time, it has been tested only very recently. 1 Computer calculations have shown that by adding the second harmonic it should be possible to increase the synchrotron phase -space acceptance of PPA at capture by a factor of 2. Since the synchrotron acceptance increases with energy, second harmonic needs to be added only during the first few milliseconds. For a test, one of the existing drift tube stations was modified to produce the required second harmonic voltage. Each of the remaining three drift tubes then has to produce a higher fundamental voltage. Phasing is done via a second harmonic reference which has the desired phase relation to the fundamental. This signal is generated in the master oscillator. Ini- tial experiments have yielded an intensity gain in excess of 5°$>. Although only described for PPA, the method can easily be adapted to other machines. IP. I. Lebedev, et al., Proc . VI. Int. Conf. High Energy Accel., Cambridge 1967, CEAL-2000. FT- Engineering, Study of Thermal Problems in Ferrites of AGS Accelerating Cavities . E. JABLONSKI AND V. J. BUCHANAN, Brookbaven National Laboratory - Expressions for radial and transverse temperature profiles in a ferrite disc heated internally by a high frequency alter- nating magnetic field of an accelerating cavity were dev- eloped from Fourier's equation for heat conduction. Analysis was based on a heat dissipation method presently used in the AGS accelerating cavities. In this method, ferrites are sandwiched between solid copper discs which are water-cooled at the outer edge. Temperature functions thus developed were used in equations for thermal stresses to determine the pattern of stress distribution and tem- perature gradients inside ferrites. Numerical results have shown that the present method of heat dissipation would be inadequate to cool the larger ferrites that are required in accelerating cavities of the AGS Conversion Program. However, a cooling plate with internal water passages was found to be an effective meliorator of ther- mal stresses. Derived equations are general in character and could be applied to similar problems of heat dissipa- tion. *Work performed under the auspices of the USAEC. F8 . Application of the Two -Power -Supply Method to the Ferrite Bias of an RF Resonator of a Rapid-Cycling Syn - chrotron .* LOUIS L. REGLNATO AND BOB K. SMITH, Lawrence Radiation Laboratory - The -ferrite bias equipment for the rf resonators of high-repetition-rate synchrotrons is expensive. This is a result of the high voltage necessary to overcome the back emf of the unsaturated ferrite at the beginning of the sweep, and the high current necessary to saturate the ferrite at the end of the sweep. For the high-frequency resonators of the Omnitron, which sweep in 6 ms, the initial voltage required is 90 V b>u.t. drops to 20 V during the first ms, when the current reaches one kA. The voltage remains low for the remainder of the sweep, while the current increases to 20 kA. To meet these requirements as inexpensively as possible, a pulse- type power supply is used during the first ms, and a high- current power supply through the remainder of the sweep. Smooth current transfer is an inherent property of the circuit. Inductance, which is surprisingly costly, is kept to a minimum by a "sandwich" bus bar technique. An SCR switch reverses the current every other sweep, so that the full hysteresis loop of the ferrite is used. A regulator circuit forces the bias current to follow a reference pulse. *Work sponsored by the USAEC . F9- Non-linear Effects in "linear" Ferrites at Hig h Rf Fields .* G. RAKOWSKY, Brookhaven national Laboratory - Recent tests on ferrite materials being considered for new AGS Conversion accelerating cavities have brought to light non-linearities which can cause instabilities at high rf fields. The most troublesome non-linearity in this respect is the variation of incremental permeability as a function of rf flux density. A parallel resonant LC circuit, with ferrite as the inductive element, exhi- bits a skewed response curve which may become multiple - valued at sufficiently large amplitudes. All the high-Q ferrites under consideration exhibit such instabilities and may in fact limit the peak rf voltage at which the new cavities may be operated. A circuit model has been analyzed and results compared with measured data. *Work performed under the auspices of the USAEC. F10. Digital Measurement of Ferr i te Hysteresis Loo^s . J. E. KATZ, Lawrence Radiation Laboratory ; Q. A. KERliS AND B. R. SANBBERG, National Accelerator Laboratory - The input data needed for engineering computations on ferrite for cavity tuning are almost nonexistent in in- dustry or private research. It would appear that the accelerator designer's choice is either to accept crude input data and play safe by overdesign, or take time out to assemble a measuring system adequate for close design. We chose the latter alternative; this paper describes our digital measuring set for major and minor hysteresis loops in ferrite. The B integrator operates under a hardwire program with digital drift and zero correction. A small control computer formats the output data for typewriter, cards, paper tape, or magnetic tape. A code, run on a separate computer, fits the measured data points to any one of several compact series expres- sions for the B-H loop, presents analogue plots, and derives numbers for permeability, stored energy, and Q. Fll . t S implified Desirn Techniques for Distributed Power Amplifiers for Synchrotron and Cyclotron Driver Applications ."* WILLIAM L. GAGNON AND BOB H. SMITH, Lawrence Radiation Laboratory - The design of distributed power amplifiers has been simplified through the use of a set of design charts and simplifying circuit techniques. A circuit in which the anode and grid lines are built from bridge-T constant -resistance networks seems to be best. These lines have, an image impedance that is resis- tive and of constant value for all frequencies, and there- fore do not require terminating half sections. For a given characteristic impedance and shunt capacitance, the bridge-T lines have about twice the bandwidth of the constant -K lines. The design of the ferrite transformers for matching the anode and grid lines to standard line impedances has been simplified by means of design charts and tables. These amplifiers are simple to build, very stable, and require no experimental adjustment for satis- factory operation. A 3-5~kW amplifier that operates from 1.5 to 75 MHz is used to illustrate the technique. *Work supported by the USAEC. F12. The Electrical Breakdown of Vacuum Insulated Electrodes Under Radio Frequency Stress .* ROBERT L. KUSTOM, Ar^onne National Laborator y - The theories which have been proposed to explain the catastrophic breakdown of vacuum insulated electrodes have considered initiation of the process by electrons, ions, electrons and ions, or massive microparticles. Analysis indicates that under stress by radio frequency fields in the range of 20 to 120 MHz electron-induced breakdown would be slightly affected and ion-induced breakdown would be measurably altered. Apparatus that can compare electrical break- down of electrodes operated at 60 Hz to radio frequency has been built. A relatively low voltage, high power cw radio frequency signal is transferred to high voltage across the electrodes in a coaxial resonator. Radio frequency voltages in excess of ^00 kV should be possible with this system. Measurements will be made at discrete frequencies of 20, ItO, 60, 100, and 120 MHz. Vacuum on the order of h x 10~° torr is attained with an oil-^free pumping system of cryosorption and ion pumps. The pro- gram is in the initial stages of operation. *Work performed under the auspices of the USAEC. F13 • Numerical Design of the Shape of an Azimuthally S ymmetric RF Cavity that Resonates at Given Frequencies and Has Zero Response at Other Specified Frequencies .* FRANCIS C. YOUNGER AND PHILIP F. MEADS, JR., Brobeck and Associates - The vector wave equation is formulated in terms of rH_i, using finite difference methods and applied to a series of lattice points in the r-z plane. The resonant frequencies are determined by solving an eigen- value problem where the dimension of the eigenvectors is equal to the number of lattice points. The nonuniform lattice spacing in the radial direction is chosen such that the operator matrix is symmetric and banded, simpli- fying the solution of the eigenvalue problem. For the eigenvectors associated with a given cavity shape, the resonant frequencies are obtained for perturbations of the boundary by the Rayleigh-Ritz Method. The set of perturbations is then formulated into a linear program- ming problem whose solution yields the optimum cavity shape . *Work supported by the USAEC. INVITED PAPER FlU. Safety Guidelines for Accelerator Installations .* H. PAUL HERNANDEZ, Lawrence Radiation Laboratory - The AEC safety guidelines for high energy accelerator facilities are reviewed together with other guidelines and codes . Some current safety problems are also discussed. There appears to be no shortage of knowledge, but collecting rules is not the total answer to safety. We all have some guidelines that we follow, but the correspondence is not always too clear between what is written and what is practiced. ♦Work performed under the auspices of the USAEC , F15- Tables for the Determination of the Lateral Shielding Requirements of High Energy Electron and Proton Accelerators . KERAN O'BRIEN, USAEC Hea l th and Safety Laboratory-NY - Neutron dose -equivalent rates transmission tables for lateral accelerator shielding have been calculated to assist a shield designer who needs realistic shielding data in a short time, and •who may be required to readjust his results frequently as machine design is modified. In one case an average shielding material having the properties of aluminum is assumed, and the hydrogen concentration is varied to account for differences in water concentration; in another, an iron shield is assumed. The geometry is cylindrical, neutrons being produced in a central accelerating structure of iron or copper, and absorbed in side-walls parallel to it. The neutron source is assumed uniform and infinitely long, which for most purposes means on the order of 10 meters long. The tables apply to electron and proton beams accelerated to energies greater than 0.8 GeV. Fl6. Radiation Studies Around Extracted Proton Beams at Nimrod . K. B. SHAW AND G. R. STEVENSON, Rutherford High Energy L aboratory - Measurements are reported of the major dose contributing components of the secondary radiation produced by the interaction of 7~GeV particles in external targets. The production, composition, trans- mission, and energy spectrum of these particles have been studied and the possible variations in spectra are discussed. Standard dosimetry techniques were used involving flux-density determination from activation detectors and dose -equivalent estimation by threshold techniques, films and thermoluminescent detectors. Measured values of neutron flux density are compared with those calculated for a simple shield model. FIT • Gamma Ray Background Analysis of the NASA Lang ley Research Center SREL 600-MeV Proton Synchrocyclotron for the Relatively Short and Long-Lived Gamma Kays . EMANUEL RIND, NASA - Langley Research Center - The NASA Langley Research Center Space Radiation Effects Laboratory 600-MeV proton synchrocyclotron has a very complex beam transport system. Experiments are often conducted at various points along this system. For this reason, and from the health physics standpoint, the gamma -ray background should be known. Various pertinent stations were studied five days post irradiation and directly after operating the beam degraded from 300 MeV to less than 100 MeV for one-half hour. Spectra for the stations were obtained with a 2X2 Nal (Li) scintillator, and the activation analysis was performed by stripping technique. This report gives the analyzed results for a typical station for the rela- tively short and long-lived gamma rays, giving the energy, relative intensity, daughter radionuclides, half lives, and reactions. The experimental setup, calibrates, and other pertinent information are included. It is inter- esting to note that fission products from these proton energies have been reported by both CERN and ORNL; the SREL experiments corroborate their results. Also, al- though very complex spectra were produced, almost every peak corresponding to the daughter radionuclides was analyzed. Fl8. Primary Safety Problems of Particle Accelerators . WM. CORNELIUS HALL, Ch?mt rce l aboratories - Particle Accelerator safety problems are primarily those of acti- vation and shielding. The phenomena of activations from various nuclear" particles and from photons is relatively well known. Use of low activation materials at exposed locations and of adequate shielding at all locations is basic to the art of constructing an accelerator facility that will be safe in operation and will need minimum cooling time. Side effects must also be considered rela- tive to safety. Electricity, heat, or even sound in the wrong place may prove hazardous both to personnel and to a successful experiment. The know-how and the materials that exist today permit the design and construction of particle accelerators, large and small, of various types, all radiologically safe both in operation and after shut- down. Good design and construction followed by the rou- tine safety procedures associated with such facilities will accomplish this objective. F19- A Past Protection System for Linear Accelerators .* DALE T. VAN BUREH, Los Alamos Scientific Laboratory - The high beam current in the Los Alamos Meson Physics Facility accelerator constitutes a safety hazard to both personnel and equipment. It must be possible to inhibit beam injection rapidly and reliably in the event any condition occurs along the accelerator which will result in a beam spill. A hardware "fast-protect" system based on transmission line principles has been developed which will provide a beam-inhibit signal in less than 10 juse-c after detection of an alarm condition anywhere along the 3 000 -ft length of the facility. An indication that a shutdown occurred, along with an identification of the source which initiated it, are passed through an inter- face to the central control computer. The hardware is fail-safe to single component failures and features computer testing of the system integrity. Some details of the design related to device selection, ground isola- tion, and fail-safe features will be discussed. Results from a prototype system installed on a computer-controlled electron linac will be presented. *Work performed under the auspices of the USAEC. F20 . The University of Tor o nto Solid-State Interlock System . E. W. HORRIGAN, R. MILIAR, AND K. SCHWEDTMANW, University of Toronto - The interlock system in use at the University of Toronto Linac Laboratory is based on solid-state computer logic circuits. These eliminate many of the problems associated with conventional relay interlock circuits (such as bulk, difficulty of modifi- cation, contact wear, and complexity of contact arrange- ments); they also make unauthorised tampering much more difficult. The system incorporates duplicated logic on all functions and an "error check" section, which senses logic malfunction and the existence of mutually contra- dictory inputs. The various interlock operating modes are programmed by means of plug -in program boards which allow operation only in the specific authorised mode. Selector switches allow logic levels to be fed to any interlock input, bypassing the selected input for test or verification purposes, but in so doing they break the main interlock output to ensure that no interlock is overridden without authorisation. Authorised bypas- sing of minor interlocks requires a key held by the Chief Engineer. In addition, bypassing locks affecting personnel safety requires the use of a second key held by the Radiation Safety Officer. F21 . New Personnel Interlock System and Procedures for the RPI Linac Lab . J. HAKEN, D. S. MORSE, AND R. M. RYAN, Renssel ae r Polytechnic Institute *- Experience indicates that periodic modifications to personnel interlock system operating procedures (nuisance modifications) increase user awareness. A modular interlock system which permits easy modification of the forced inspection sequence has been designed and installed at the RPI Accelerator Labora- tory. The system provides for forced area inspection within specified time periods. Audible signals alert workers when the inspection is in progress. *Work supported by USAEC under Contract AT(30-3)-328. F22 . A Multichannel Radiation Monitor with Logarith - mic Response from 0.1 to IP 13 mR/hr .* T. G. DZUBAY AND R. E. POLLOCK, Princeton University - A radiation moni- toring system having a very wide dynamic range, relative immunity to radiation damage, and providing continuous audible information feedback to the user was built for the 55-MeV Princeton AVF Cyclotron. A remote sensor in each room consists of a 1 x 2-in. plastic scintillator and photomultiplier . At the control room there is a dc amplifier with output proportional to the log of the anode current, and hence to the dose rate. This is examined by two independently adjustable set points with DTL outputs which establish limits for human occupancy and for radiation damage to equipment respectively. For each channel discrete pulses from the photomultiplier are also amplified and operate a loudspeaker placed near the detector. When the lower set point is tripped the speaker broadcasts a siren-like tone. A failure condi- tion logic signal is generated if discrete pulses are not present when the low level set point is not tripped. Although this type of detector does not directly respond to slow neutrons, it does indicate the radiation hazard by detecting the fast neutrons and capture gamma rays which accompany them in a cyclotron environment. *Work supported in part by the USAEC . F23- 1 Remote Maintenance Concepts for the Los Alamos Meson Physics Facility . MAHLON T. WILSON, LASL - The LAMPF design beam of 1-mA, 800-MeV protons is capable of inducing thousands of curies of activity in targets and beam stops. Comparable activity is created in magnets, collimators, beam pipes, and shielding by secondary pro- tons and neutrons. High activity levels exist over hun- dreds of feet of beam channel. The targets and stops are compact items that require routine replacement. They will be handled by mechanisms that position, cool, and vacuum seal. The mechanisms will be withdrawn into shielded containers for transport to a hot cell for tar- get or stop replacement. Maintenance or replacement of all other activated equipment involves handling large sizes and weights on a non-routine basis. Vertical access is provided to all equipment through movable roof shutters incorporated into the shielding. A shielded, floorless room is lowered into the shaft created by opening the shielding shutters. The room houses remote handling equipment capable of removing or performing minor repair work on all activated items. Lead glass viewing windows are mounted in the ceiling of the room through which operators standing on top of the room can observe their work. A self-propelled gantry transports the 200-ton room between work areas. The load is carried on four surplus military aircraft landing gear. F2 1 * . t General -Purpose Servo-Manipulator for Remote Maintenance of Accelerators .* C. R. FLATAU, Brookhaven Mational Laboratory - Induced radioactivity in many ac- celerators is at a sufficiently high level so that direct maintenance or modification work on the machine is severe- ly hampered or entirely precluded. To continue opera- tions, one has to resort to some form of remote main- tenance. A preferred technique would involve the use of commercially available mechanically coupled master-slave manipulators. However, since these cannot be adapted to the restraints existing in most accelerators, one would like to have an equivalent tool one could adapt . To fill this specific need, a prototype servo -master -slave manipulator was developed and built . It has an extremely compact slave arm coupled only electrically to the mas- ter, and is thus able to work in the confined spaces of accelerators, and do this' even while the beam is on. Other essential features, like proportional control and bilateral force reflection are maintained, while overall dexterity and versatility is improved. This is achieved by improving frequency response and feel sensitivity, providing better articulation, and introducing continu- ously variable force ratios. Analysis of development cost shows that use of this arm is economically justifi- able. *Work performed under the auspices of the USAEC. F25 . Application of Remote Handling in the PS-T unnel. M. ELLEFSPLASS, R. A. HORNE, AND W. RICHTER, CERN - Two hands and a crane are controlled from the ring centre via 3°0-m long cables and observed with three closed- loop TV-chains. This installation, with more than 30 remote controlled functions, is capable of performing work along 1+0 meters of the PS -ring-tunnel. The second hand, which has been developed at CERN, executes the more delicate work such as disconnecting ordinary water and electrical connectors of different types. One test opera- tion was the removal of a vacuum tank with a septum mag- net of the ejection system. Although this equipment was not designed for remote handling, only the connection to the power cable could not be removed from a distance. All the other work -- vacuum connections to chamber and pumps, electrical and water connections, lifting out onto a chariot -- was done with no one present in the ring tunnel. F26 . Neutron Flux in a Labyrinth Due to a 3~GeV Pro - ton Beam Incident on Lead . W. SCHLMMERLIBG,* AND M. AWSCHAL0M, T Princeton -Pennsylvania Accelerator - A series of measurements are reported of the neutron fluxes along a labyrinth with four bends, leaking into an external beam cave of the Princeton-Pennsylvania Accelerator. The neutron fluxes were produced by the 3-GeV proton beam incident on 8-in. thick lead targets at the mouth of the labyrinth, and three feet upstream and downstream. Measurements were made by activation of carbon, sulphur, indium, and cadmium-covered indium at 26 locations along the labyrinth. The results have been normalized to 10^ incident protons/sec. A Monte Carlo calculation of the thermal neutron flux has been made by R. G. Alsmiller, et al. 1 The calculations and the indium measurements agree very well. *Princeton -Pennsylvania Accelerator. ^National Accelerator Laboratory. iR. G. Alsmiller, et al, private communication. F2T • Radiation Damage Studies of Zero Gradient Syn - chrotron Magnet Insulation and Related Materials . * F. W. MARKLEY, G. A. FORSTER, R. BOOTH, Argo nne National Laboratory - Radiation effects on the electrical and mechanical properties of several insulating materials have been measured. These include several epoxy resin systems both glass reinforced and unfilled, two high temperature films, and a glass bonded mica. Samples were gamma irradiated under ambient conditions to lO-"-^ rads at rates up to 10' rads per hour. The electrical tests given after irradiation were volume resistivity, voltage breakdown, dielectric constant, and dissipation factor. The samples were tested at 30°C and low humidi- ty. No sharp changes occur that would predict electrical breakdown of magnet insulation. The voltage breakdown strength of the epoxy samples gradually decreased to about one-third of the original. Several different mechanical properties were measured to compare their radiation sensitivity and their practicality as radia- tion test methods. A new bulk shear tesb was selected as the preferred method; it gives good sensitivity, ease of fabrication and testing, small size, suitability to gamma ray or electron tests, and definitive numbers use- ful in stress calculations on dissimilar systems. For most systems rapid degradation begins at about 5 x 10° rads, although flexible systems lose their flexibility by 2 x 10^ rads. *Work performed under the auspices of the USAEC. F28 . Mineral-Insulated Magnets for High Radiation En - vironments" ! A. HARVEY AND S .A . WALKER, Atomic Energ y of Canada Limited and Py.rotenax of Canada Limited - A mineral- insulated conductor for electromagnets exposed to high radiation fields is described. The copper conductor is insulated by compacted magnesium oxide powder, which has a very high tolerance to all types of radiation. The outer containing sheath is squared to improve the pack- ing, and heat transfer. Coil configurations with either external cooling or with hollow internally cooled con- ductors, are described. Joints and terminations of the conductor are discussed. F2 9 • t The "S phere Dump" - a N ew Low-Cost High-Po wer Beam Dump Concept and a Cataly tic Jlydro gen-Cxycen Re - combiner for Radioactive Water Systems .* D.R. WALZ Ai!D L.R. LUCAS, Stanford linear Accelerator Center - A new high-power beam dump concept was developed at STAC. Its principal features are relatively low pro- duction costs, simple assembly procedures, compactness, and rather high power absorption capacity. The main power absorption medium is a water-cooled bed of 1 cm dia aluminum spheres contained in a tube. The dump is rated at 500 kW and a prototype of such a "Sphere Beam Dump" dissipated successfully ^95 kW at an electron energy of 18 GeV. It is competitive with other de- signs down to 50 kW. The main features of the dump are discussed and illustrated. Heat transfer in the bed of spheres, flow and mixing of the coolant, de- tection of burnout, and the aforementioned experiment are treated in detail. Fotential applications for other high-power absorbers are indicated. Radiolysis and resulting evolution of free hydrogen from such a dump and other water-cooled power absorbers presents safety and disposal problems at all high-current par- ticle accelerators. A catalytic hydrogen -oxygen re- combiner fully integrated into a closed-loop radio- active water system and interlocked with the acceler- ator operation was developed and built. A detailed description supported with illustrations is given with emphasis on operational parameters, instrumentation, safety, catalyst tests and performance. *Work supported by the USAEC . F30. Stopping a 200-MeV, UO-kW Proton Beam .* G. S. LEVIEE AND W. H. MOORE, Brookhaven Rational Labora - tory - A description of the problems involved in rou- tinely stopping the proton bea.ni from the linac of the converted AGS is presented. Estimates of the levels of radioactivity, heat input, and radiation damage arising from the passage of the lO 1 ? protons per second through matter are given. The analysis of materials with appro- priate properties to minimize hazards and provide relia- ble operation is outlined. The solution chosen, a contin- uous-flow water stop, is described, and the expected levels of radioactivity, shielding required, and expected lifetime of elements of the system are reported. Work performed under the auspices of the USAEC. F31 . The Ra diation Shielding and Beam Dumps for the KAL 100-GeV Proton Storage Rings . MIGUEL AWSCHALOM, lia tional Accelerator Laboratory - The beam losses ex- pected in the HAL 100 -GeV storage rings are reviewed from the point of view of radiation damage to compo- nents and required biological shielding. It is shown that the required shielding is essentially the same as adopted for the KAL main accelerator: about 1.1 x 103 g/cm 2 . The storage rings will hold 16 MJ of beam energy in each direction. In case of fast beam ejection (~7 usee), this energy must be absorbed by a large enough mass to avoid excessive temperature excursions. It is shown that beryllium or graphite cores in a steel shield would make a satisfactory beam dump. F32 . External Ta rr et Irradiation Facility for the Princeton University AVF Cyclotron .* C. C. FOSTER, B. GREEUEBAUM, AllD E. A. PHILLIPS, Princeton University - A comparatively simple and inexpensive facility is being completed to irradiate targets in the external beam of the Princeton University AVF Cyclotron. The target can be removed and used relatively quickly. The target it- self is held and cooled by a version of the Berkeley 83-in. Cyclotron target holder block, which also acts as a cyclotron beam stop. We estimate, on the basis of our calculations and Berkeley's experience, that the block will easily handle the 2.5-kW we expect to deliver with a 50-^A beam of 50-MeV protons, or similar beams of other ions. The target holder block is lowered into a vacuum chamber on a supporting column which provides the block with cooling water and electrical leads for beam and temperature monitoring. The chamber is surrounded by shielding to attenuate fast neutrons daring bombard- ment and to protect personnel hand! ing the block after- wards. After irradiation, the block is purged of water, vacuum is broken, and the block is lowered into a lead cart through a gate valve at the bottom of the facility. The block is then taken to a shielded handling area, where it can be disassembled quickly. *Work supported in part by the USAEC. F33- Shutter and Collimator with Rotating Radiation- Cooled Elements for the Beam from t he Princeton AVF Cyclotron . * C. C. FOSTER, Princeton University - A beam collimator and shutter assembly has been designed and fabricated to define and interrupt the high maximum areal power density (30 kW/cm 2 ) external beam anticipated for the Princeton AVF Cyclotron. Pairs of tungster.-coated graphite cylinders, which rotate at 300 rpm about paral- lel axes a precisely adjustable distance apart, define the beam in each of the horizontal and vertical direc- tions . The thin tungsten coating is used to retain the good beam-defining properties of a heavy metal while minimizing the buildup of long-lived radioactive isotopes in the slit cylinders. A similar uncoated rotating graph- ite cylinder, which is raised and lowered by an air cylin- der, operating in a fail-safe mode, functions as the beam shutter. The power of the beam incident on these cylin- ders is d-issipated by thermal radiation to surrounding water-cooled structures. Tests with an electron gun show that the slit cylinders can successfully dissipate 20 kW/ cm 2 with no indication of deterioration or overheating of critical components. "Work supported in part by the U. S. Atomic Energy Com- mission and the Higgins Scientific Trust Fund. F3 ^ • Improvements in Liquid Hydrogen Target Techni aaes . MITCHELL 0. H0ENIG, Cambridge Electron Accelerator, Ha r- vard University - In the process of converting liquid hydrogen target systems from liquid cooling to mechanical refrigeration we have developed new techniques to aid the high energy physicist. These include: thermal suppres- sion of local boiling, target insulation by means of in- ternal shielding, rapid transfer of liquid from thin wall target to safe container, and isolation of the liquid hydrogen in this condenser vessel to permit safe access to experiment . The paper describes hydraulic as well as refrigerating techniques used for 100-ml, 2-liter, and 6-liter targets utilizing 10 to 20 and 35 to 50 watt mechanical refrigerators . F35 . A Liquid Hydrogen Target for SIAC's 30-mA Elec - tron Beam . R. BELL, H. CIAY, J. MARK AND W. PIERCE, Stanford Linear Accelerator Center - A unique liquid hy- drogen target capable of handling SIAC's high current (30 mA), high energy (20-GeV) electron beam is described. A 35-liter liquid hydrogen reservoir is used to condense the gaseous hydrogen contained in the target flow loop. This loop consists of a 3-in. dia, 0.003-in. thick seam- less aluminum target cell mounted in one leg of a "u" tube arrangement. In the same leg, a small axial fan submerged in the liquid hydrogen circulates the liquid through the target cell and heat exchanger. The top of the "U" tube is joined together with flexible metal hose which acts as the heat exchanger and completes the flow loop. Suspended from the rigid bottom of the loop are a dummy and a carbon target. The entire system can be positioned with any of these targets in the beam line by remote actuators. Density variations as high as 10^ due to beam heating were experienced in similar targets which did not employ this circulating technique. Experi- mental results show that in the circulating target these density variations were reduced to less than 1/2$ with heat fluxes as high as 5KW/cnf* per cm of target length. F36. Refrigerated Liquid Hydrogen Targets at the Zero Gradient Synchrotron .* RICHARD D. ROMAN, Argonne Rational Laboratory - Refrigerated LKj targets having a volume of 0.3 to 2 liters have been operated in high energy physics experiments on Argonne' s Zero Gradient Synchrotron. These LKp targets use commercially available cryogenic refri- gerators. Experience has shown these refrigerated tar- gets are as reliable, safer to operate, less expensive to operate, and more versatile than the reservoir targets commonly used. Refrigerated targets use a closed loop, hydrogen condensing and recondensing design. A modular design of the target system has made possible the stan- dardization of auxiliary equipment. The standard equip- ment has in turn been designed into self-contained, por- table consoles and equipment carts which are easy to maintain, require fewer spare parts and can be located in easily accessible areas remote from the cluttered experiment site. The refrigerated target system consists of four major components; the universal refrigerator con- tainer to which the vacuum jacketed target is attached; the pump, valve and electrical distribution cart; the compressor; and the control console. For larger targets a design using a compact heat exchanger at the target has been proposed. This condenser would be cooled by a remotely located, commercially available, cold gas gen- erating refrigerator. *Work performed under the auspices of the USAEC. F39- Self -Optimizing Target Control S ystem. CHARLES " W. POTTS AND DONALD F. MARCKS, Argonne National Labora - tory - A unique control system to rapidly drive meson targets into critical position has been developed and used in the Zero Gradient Synchrotron. This "time opti- mized" system increases the spill time and provides new possibilities for beam handling. The motive force of this new system is a current driven coil reacting with the magnetic guide field. The driving coil holds the tar- get in any desired vertical position without the need of mechanical stops. Repeatable position is maintained re- gardless of operational changes of magnetic field, times of targeting, and changing friction. For any given set of mechanical, magnetic, and electrical conditions, an optimal target positioning time exists. Attained "opti- mal" performance cannot be maintained by an open-loop system if even the slightest change in system parameters occurs. The "self -optimizing" target control system achieves the proper "bang-bang servo" performance by learning and storing information regarding behavior on previous cycles. Once positioned, the system transfers to a linear servo mode to maintain position. In the linear servo mode, programmed variations in target height may be made to complement an experiment. Target position- ing times of 20 milliseconds have been realized with stability and repeatability. Greatly expanded utilization of this control system is planned. *Work performed under the auspices of the USAEC. F37. Insulated-Target Instrumentation in the AGS Slow External Beam . G. W. BENNETT, Deutsche s Elektronen - Synchrotron - Absolute measurements have been made of the charge transferred by 25-GeV protons from thin, insulated, aluminum plate targets in vacuum. The results are re- ported for various thicknesses, orientations, and bias. Beam flux measurements were made by means of the 13 C(p,pn) 11 C monitor reaction using polyethylene foils. Applications of these targets to beam intensity, profile, and emittance measurements at the AGS are discussed, as well as the associated circuitry and the limitations of the technique . On leave from Brookhaven National Laboratory. F38 . Insertion and Extraction of Internal Targetry at the Zero Gradient Synchrotron .* THADDEUS D. CASSIDY, ANDREW J. GORKA, AND ROBERT B. WEHRLE, Argonne National Laboratory - A new internal meson targeting system is in current use within the ring vacuum chamber of the ZGS. In this system, the target manipulators are changed with- out loss of the ring vacuum. The changes are accomplished with short interruption of useful beam time and with mini- mum radiation exposure to personnel. Two target manipu- lators operate on the track simultaneously supplying two secondary beams and an extracted proton beam from each machine pulse. The system consists mainly of the target- ing manipulators, the insertion and extraction apparatus with an isolation chamber, and a multi-bus-bar track with a 100-in. linear positional potentiometer. Each manipulator is a separate unit with no connecting exter- nal mechanical drives or wires. Small wiper contacts supply all power and information. The lack of physical trailing connections allows the manipulators to easily shuttle in and out of the ring vacuum chamber through the isolation chamber's vacuum valves. Direct coordinate positional readouts are displayed in digital form for the operators. Circuits automatically compensate for the track not being parallel with the coordinate systems. The system has been operating successfully for one year. F^O. A Taut Wire Alignment System with Automatic Readout of 5 of the 6 Degrees of Freedom of a System of Solid Bodies . WILLIAM DAVIES -WHITE , Stanford Linear Ac - celerator Center - The alignment system outlined below was developed at SLAC . The line reference is a taut wire carrying a 10-kHz 60-mA signal. The sensor has "bucked" coils wound around a laminated rectangular core. At the magnetic center of the sensor the induced voltages on each half of the sensor cancel one another. Displace- ment of the wire induces a voltage linearly dependent on the displacement, up to the full sensor aperture T l/U in. The induced voltage is de -modulated, then amplified re- sulting in a dc output; typically, the gain of the ampli- fier may be varied from 5 to 50 mV per 0.001 in. displace- ment. With two taut wires and 5 sensors, 5 degrees of freedom of each solid body in a complex system can be monitored. In practice, two sensors are mounted orthog- onally in one unit . Four of these units mounted on a solid body (8 sensors) determine the 5 degrees of free- dom, yet with logic, any sensor is redundant in the event of failure. The system's stability is good, with a unit cost of about $25, the practical length of a taut wire is about 300 ft between nodes . F^l . A Precision Goniometer for Use in Accelerators . E. A. THE3AD0. Cambridge Electron Accelerator - A very successful goniometer design has been in use at CEA. A reproducibility requirement of 0.2 milliradi-ir^s maximum has been achieved over 1^0 milliradians (8°) in two crys- tal axes and one longitudinal axis. All materials are compatible with ultrahigh vacuum requirements in the presence of high radiation. The goniometer was built to hold a diamond target to produce polarized photon bear.s. No deterioration of operating characteristics is observed after over 1000 hr. of operation. *Work performed under the auspices of the USAEC. Yh2. Low Conductivity Cooling VJater Systerg . CEOfGE HOMSY AND WILLIAM J. JOKES, Cambridge Electron Accclc-ra - tor - It has been estimated that upwards of 80$ of all electrical power delivered to an accelerator must be dissipated as heat by means of low-conductivity cooling water. The following aspects are discussed: a. elcir.cn- tary chemistry, b. equipment necessary to produce and maintain low conductivity water, c. sources of and the processes involved in contamination of the low-conduc- tivity water, d. corrosion of the distribution system and the heat loads, e. maximum conductivity that can be tolerated in different components, f. significance of potentials that may exist at junctions of dissimilar metals, g. level of personnel required to operate and maintain the equipment, h. pollution problems raised in the disposal of affluent chemicals employed in regenera- tion of resins, and i. safety; i.e. hazards involved in handling the acid and caustic solutions used in regenera- tion. FU3. Accelerator Cooling System Design and Eco - nomics . E. EHO, W.P. CARPEI.'DER, E.C. LITSINGER AND M.K. LYSTER, Lawrence Radiation Laboratory - The reported costs of low conductivity water JLCW) cool- ing systems for various accelerators range from 08.OO per kilowatt to over $50.00 per kilowatt not including water distribution. This report explains the reasons for such variations in unit cost. The report analyzes the effect of the following on the unit price of cooling towers, of heat exchangers, and of other components of a cooling system: a) at- mospheric conditions and geological location, b) maximum allowable temperature of the cooling water supply to equipment, c) maximum allowable tempera- ture rise of the cooling water as it passes through the equipment, and d) poor control of the flow of the cooling water through the equipment. An analy- sis is made of the functional suitability and the relative costs of alternate methods of cooling. An examination is made of various types of LCW piping materials as to their suitability and limitations and as to their relative costs . Curves and tables are submitted as an aid for the preliminary estima- tion of cooling system costs for any particular accelerator. Methods are suggested for reducing the unit costs of cooling systems. Tkk . Inert Gas Purifier for SLAC's 2-m Streamer Cham - ber . PER THTNGSTAD, Stanford Linear Ac ce lerator Center - This purifier was built to purify the 90% Ne-10% He gas mixture in SLAC's two-meter streamer chamber. The stream- er chamber had two gas cells race-track shaped, each with overall dimensions of 95 X &5 x 12 inches. The cells were made of polyurethane foam; 12m 2 of 2 -rail mylar separated the gas from the atmosphere. A l/2-in. dia, 95-in. long mylar tube with a U-mil wall ran through one of the cells and contained hydrogen gas at 80 psig. Initially, a chem- ical system was built to purify the gas. later a cryo- genic system was built and successfully tested in last summer's experiment. Eecause of the large mylar surfaces the pressure regulation of the chambers is very critical. The system is described as well as its capacity to absorb contaminants . Some cost figures and data from last sum- mer 's experiment are included. Both the calculated and the measured contamination rate increase in the cells are described. A mass spectrometer was hooked up to the sys- tem, and the purity of the gas in the chamber was meas- ured as it was purified. The apparent purity requirement for good streamers is described. Gl. t Some Engineering Problems of the Serpukhov Accelerator . E. G. KOMAR, The Research Institute of Electrophyslcal Equipment , Leningrad, USSR. G2.t Design of the Main Ring Magnets for the NAL 200-GeV Synchrotr on. R. J. LABI, Argonne national labora - tory ; L . C . TENG , National Accelerator Laboratory - Two types of bending magnets are used to match the beam width in the separated function FODO lattice of the main ring of the NAL 200 GeV accelerator. Bending magnet Bl has an aperture of 5 x 1.5 in., an overall dimension of 25 x lb in., and a 12 -turn coil; bending magnet B2 has an aperture of k x 2 in., an overall dimension of 25 x lU in., and a l6-turn coil. With proper geometry and a small amount of pole -face crenellation, the good-field regions of these magnets extend over ~80$ of the aperture to beyond 20 kG. At 18 kG, which corresponds to 1+00 GeV, the saturation is only 3-7$ and the excitation current is U716 A. The quadrupole magnet has a useful aperture of 5 x 2 in., an overall dimension of 25 x 17 in., and four 17 -turn coils installed in enlarged coil slots. The quadrupole s are excited separately from the bending mag- nets to provide tuning flexibility. With proper cross- section geometry and pole-face shaping the good-field region of the quadrupole extends over ~80% of the aper- ture to a field gradient beyond 250 kG/m required for U00 GeV. Most of the magnetic -field design is performed with computer programs LINDA and TRIM. The factors of consideration and techniques involved in the design are discussed. G3 • t Direct Powering of the 200 -GeV Synchrotron Mag - nets From the Ut il ity Syste m. R. L. CASSEL, National Accelerator Laboratory ; J. E. VAN NESS, Northwestern U niversity - Providing power for the main magnets of the 200-GeV synchrotron includes the direct connection of static power converters to the power utilities, without the use of local energy storage. This paper investigates the engineering aspects of this magnet powering system. The power utilities response to the required power fluc- tuations, as well as the interaction of the power line stability on the magnet field regulation, is covered. The calculated effects of the performance of Common- wealth Edison Co. power distribution system under dif- ferent load conditions are presented. Included are the dominant factors related to the distribution systems behavior. Regulation and repeatability calculations relating the normal power line fluctuations to the re- quired field stability are evaluated. Measurements on the 3^5 "kV power line to be used for direct pulsing are included and evaluated with respect to the overall system requirements. Ck. Static Fewer Supplies for Pulse Loads . J. A. FOX, Rutherford Laboratory, England - The paper describes the basis and results of the study into the possibility of supplying a large pulsed magnet load (of the 300-GeV type) directly from the public power system and thereby elimina- ting conventional MG sets. The factors involved are re- viewed in terms of the accelerator and its performance and of public power system. Various methods are briefly described for stabilizing the pulse-induced voltage fluc- tuation with static reactive compensators . A guide to acceptable fluctuation limits and the significance (with practical examples) of transmission system R:X ratios are included. Considerations of the public power system in determining pulse load acceptability are described in de- tail. The paper includes the description and results of practical pulse tests on power systems - the 60-MW pulse tests (November 19&7) on the U.K. system using the Ni:nrod accelerator as the load and the 16O-MW pulse tests (June 1968) between the U.K. and French systems via the inter- connecting submarine power cable across the English Chan- nel. Conclusions are derived on pulse load acceptability in terms of specific European power systems and existing or proposed accelerators, practical limits and general guide lines, and the effect of future power system develop- ment on permissive pulse energy levels. G5- Pulsing the ZGS Directly from the Utility Line .* ALFRED ROHRMAYER AND JOHN F. SELLERS, Argonne National Laboratory - The history of extended periods of lost experimental time due to failures of flywheel motor gen- erator sets used by pulsed synchrotron magnets indicates a necessity for standby facilities. The idea of pulsing synchrotrons directly off the utility lines has become very active in recent years, and investigations have shown this to be the most attractive alternative for the ZGS. The switchover, in the event of an M-G set failure, can be made within a matter of hours; the first costs are lowest, operating costs are reduced, and reliability is increased; and it can be built in stages from partial energy to full energy capability. The first stage will be to install a 35-MVA transformer capable of pulsing the ZGS to an energy of 9 BeV with a line voltage fluc- tuation of less than Vf>. Low voltage taps will be avail- able for low energy pulsing to study the effects on the utility system. The second stage will provide for by- passing one-half of the rectifier supplies during flat- top. This limits the voltage fluctuation to a value con- sistent with continuous operation. In the full energy stage, a second transformer will be added and the system KVARs will be reduced by switching precharged capacitors. *Work performed under the auspices of the USAEC. G6. Tolerable Limits of Voltage Fluctuations Produced by Magnets Pulsed Directly off Alternating Current Power Lines ." WALTER F. PRAEG, Argonne National Laboratory - Switching magnets, for time sharing of beam lines, can be pulsed directly off the ac power line if it does not cause objectionable line voltage fluctuations. Switching cir- cuits, which are less expensive and more reliable than conventional magnet power supplies, are often all that are needed. The results of extensive tests made to deter- mine the limits of tolerable single -phase line fluctua- tions are reported. Of particular interest for beam lines of the Zero Gradient Synchrotron was a test to find the attenuation permissible for one cycle of the 60-Hz power line every two seconds. Other tests included multi- ple cycle attenuation at different repetition rates and square wave modulation of the ac power line. Thresholds of perception and irritation as functions of voltage attenuation were determined for viewing television, reading by incandescent light, and observing various sources of light. Observers used a five-grade opinion rating, and it was found that the percentages of the ob- servers likely to hold each grade in a given instance followed a binomial distribution. The results enable one to calculate the permissible magnitude of pulsed current in a given ac power system. *Work performed under the auspices of the USAEC. G7 • Ripple F ilter Sy stems of the Zero Gradient Syn - chrotron and Means for Long, Magnetically -Controlled Beam Spills .* EDWARD J. BARS0TTI, WALTER F. PPAEG, AND JAMES M. STEPHENSON, Argonne National Laboratory - Ripple frequencies in the ring magnet guide field of the Zero Gradient Synchrotron (ZGS) range from a few hertz to several kilohertz. Filter systems that reduce the ripple components to negligible magnitudes are analyzed; and the use of these systems for long-magnetically-con- trolled beam spills is described. High-frequency ripple is attenuated by a novel LCR filter. Low-frequency ripple is reduced by a feedback loop from B to the recti- fier phase control of the ring magnet power supply. The attenuation of the mid-frequency components is accom- plished with a feedback loop from B to a ripple bucking coil in each octant of the ZGS. Effects of these filter upon the quality of the RF controlled beam spill are shown. Two modes of operation for magnetically-con- trolled beam spills without RF structure are discussed. In one mode the feedback to the low-frequency loop is transferred from 6 to a spilled-beam monitor. In the second mode both the low-frequency and the mid-frequency loops are driven from the spilled beam monitor. *Work performed under the auspices of the USAEC. G 8 • Modifications to the Z G S Pjing, I'amet Power Sup - ply Generator Excitation Control . ' J0H1I F. SELLERS AKD ALFRED ROHKMAYER, Argonne National Laboratory - The i:oct desirable magnet voltage for the Zero Gradient Synchro- tron (ZGS) should be constant during rectification and inversion and as low as required in flat -top. To reduce alpha control and ac and dc harmonics, the generator ac voltage should correspondingly increase during rectify, decrease in inversion, and be as low as possible during flat -top. This was obtained by providing an electronic generator field exciter with a very high ceiling voltage and a programmable reference in the generator voltage regulator. The complexity of the programmable reference made adjustment of the magnet pulse difficult. Further- more, the transients encountered in the exciter current during transitions from rectify to flat -top and flat -top to inversion caused transients in the generator ac volt- age, considerably distorted the ac voltage on the M-G set motor stator, and increased the mechanical oscilla- tion on the M-G set shaft. It was, therefore, decided to apply a simplified scheme that would eliminate the transients at the price of a slightly higher generator voltage during flat -topping. This was accomplished by reducing the exciter ceiling voltage, eliminating the programming of the reference and setting it to constant values during rectify and invert, and by keeping the generator field current constant in flat -top. "Work performed under the auspices of the USAEC. G9- Extended FlattOD Operation of Bevatron Results from used on the future beam extraction system for a new Experimental Hall now under construction at the Ruther- ford Laboratory. The step programmed supply was devel- oped to increase machine utilization by switching the proton beam between two beam lines in the same machine burst on flat top. The supply can switch a maximum of 500 A up or down in 10 msec and maintain a level stability or ±0.005$. The maximum current capability is 1600 A, with the current levels fully variable. The second part of the paper deal s with the pulsed power supply now under design and construction using a homopolar generator, the load current being programmed by a series transistor regu- lator. A review of other techniques considered is included to show reasons for the choice. The design specification requires that the current waveform should be trapezoidal and rise linearly in 200 msec to 21,000 A max. Stability during the flat -top time should be within 0.02$ inclusive of ripple. The flat -top time is of the order of 600 msec, thence the current decreases linearly to zero in a further 200 msec. The maximum pulse repetition rate is 25 ppm. General techniques are discussed together with particular emphasis on strobing of the precision demand reference and function. W.W. SALSIG AND H.W. - In December, 1966, Generator Eov^tail Fa i lure Studies . * V0GEL, lav rence Radiation laboratory massive failures in the Bevatron generator pole dovetails wex - e discovered before the trouble became catastrophic. Preliminary investigation indicated the cracks probably resulted from cyclic loads due to the increased speed range resulting from long flattop operation. New poles were in- stalled and the generators returned to service with the length of flattop restricted. Regular inspection, includ- ing the monitoring of fatigue-sensing strain gages, was instituted. Fatigue tests of full-scale dovetails and fracture mechanics methods of analysis were undertaken. A few new cracks were initiated in the generators, and flat- top length was further restricted. In addition to gather- ing mechanical information, a number of reconnections of the electrical converters to provide continuous power bal- ance were tried and evaluated. A reconnection which great- ly reduced the speed range without generating new undesir- able vibrations was finally achieved. Since July 1968, the generators have been running with this new switching mode. Flattop lengths of 2 to 2.5 seconds, twice the length which caused the initial trouble, are now usual in opera- tion, and all crack growth appears to have been arrested. *Work performed under the auspices of the USAEC. G10. Flat Topping the CEA Alternating Gradient Mag - netic Fiel d. R.J. AVER ILL, Cambridge Electron Accelera - tor, Harvard University - A possible method of increasing the duty cycle of the (JEA electron synchrotron to perhaps twice that now achieved by current pulsing a one-turn winding around all '48 synchrotron magnet back legs is described. A half sinusoid of current applied to the winding in such a way as to flatten the magnetic field at its maximum value can, in principle, increase the time when AB/B is less than ^ l/h% from the normal 500 u,sec to about 1 millisec. Several aspects of flat top- ping by this method are discussed, e.g. absolute energy effects, magnetic circuit effects, costs, and peripheral effects on radio frequency, and beam bumps. G12. Large DC Magnet Power Supplies at SLAC * MARTIN M. BERNDT, Stanford Linear Accelerator Center - Currently a total of six dc magnet power supplies, ranging in size from 1.6 to 6.0 MW are in operation. Five of these sup- plies are static converters, using step-down transformers and thyristors; the sixth one is a two-unit motor-genera- tor set. Certain design criteria have evolved, dictated by specific needs at SLAC and by operating experience obtained over the 3-yr. period during which this equip- ment was installed. Primary power distribution is at 12.47 kV. Vacuum switches in place of circuit breakers incorporating special protective equipment to prevent complications are successfully used to do the frequent switching required by the loads. Provisions are made to permit reconnection of the output for use with the vari- ous loads. All static converters use oil-filled trans- formers, mostly of special design. Twelve-pulse recti- fier systems using SCR's are used throughout; they are operated in such a way that in at least one case the in- herently poor power factor of phase- controlled converters can be improved. A not very successful attempt was made to build some of these power supplies on trailers to make the equipment portable. It was abandoned in favor of a different approach. *Work supported by the USAEC. G13-t Recent Work on Superconducting Synchrotrons. J. D. LEWIN AND P. F. SMITH, Rutherford Laboratory, England - A brief progress report will be given of: (a) theoretical studies relating to superconducting synchrotrons, (b) development of low-loss filamentary conductors suitable for -pulsed operation, (c) plans for model magnet studies. Gll.t High Stability, High Current, Programmed Power S upplies for Nimrod Extraction Systems . F. S. GILBERT, Ra ther ford Laboratory, England - This paper describes the high stability step progranmed power supply for the Nimrod 7~GeV proton synchrotron double extraction system now in successful operation, and the new high current 21,000-A pulsed power supply for septum magnets to be G14. Measured Losses in Pulsed Superconducting Magnets. * WILLIAM S. GILBERT, Lawrence Radiation Laboratory - The feasibility of pulsed superconducting magnets in accelera- tors depends critically on the generated heat that must be removed by 4.2°K liquid helium. The attendant tempera- ture rise tends to drive the superconductor resistive, or normal. The energy loss for a cyclic sweep of magnetic field is akin to hysteresis, and for single-wire filaments, loss per unit volume is proportional to wire diameter. Practical accelerator magnets appear to require wire some 0.001-in. (25u.) in diameter. Coextrusion of many fila- ments of ductile Nb-Ti imbedded in copper or copper alloy provides the required fine filaments within a strong, high-current conductor. However, the normal material causes increased losses through electrically coupling the filaments. This coupling can be reduced with high- resistivity normal material and by twisting the entire matrix. Experimental loss data will be presented on cyclic superconductor loss in two geometries; solenoid with 1.5-in. id, 1^.5-in. od, 4-. 5-in. length, maximum field 55 kG; bending magnet (dipole) 3-in. id, 5-in. od, 15-in. length, maximum field 30 kG, random winding with epoxy binding. Conductors used are single core and multicore (filaments 0.001 to 0.002 in.), copper and Cu-Ki substrates, twisted and untwisted conductor. ♦Work sponsored by the U. S. Atomic Energy Commission. G15. Superconducting Synchrotron Magnets ." W.B. SAMP- SON, R.B. BRITT0N, G.H. MORGAN, P.F. DAHL AND J. P. BLEW- ETT, Brookhaven National Laboratory - Recent technologi- cal developments indicate that superconducting magnets capable of being pulsed with low energy losses will be available in the near future. Experience obtained from the construction of superconducting magnets for beam handling applications has been combined with energy loss measurements to estimate the refrigeration requirements of a typical synchrotron magnet. Loss measurements are presented for twisted multif ilamentary and braided con- ductors. These results are used to predict the loss that can be expected from a small-aperture dipole magnet. The use of iron to reduce the stored energy is also dis- cussed. *Work performed under the auspices of the USAEC. G16. Operating Experience with a Superconductor Mag- net in an Accelerator Experiment .* WILLIAM CHAMBERLAIN, Lawrence Radiation Laboratory - A superconducting sole- noid was incorporated into a physics experiment at the LRL 184- inch Cyclotron. The magnet was kept supercon- ducting for the entire run, July to December 1968. The solenoid has a 4-1/4 diameter warm bore and an overall length of 3-1/2 ft. The field intensity is 60 kG. The proposed conventional solenoid which it displaced was 11 ft long. Buried in a steel and concrete shielding wall, the solenoid was the least accessible of all components in the experiment. This condition imposed great emphasis on the reliability of- the coil and cryostat structure. The cryostat is cooled by direct evaporation of liquid helium and liquid nitrogen. The liquid helium supply Dewar and vacuum pump are located 25 ft from the mag- net in a region accessible only with accelerator beam off. Liquid-helium automatic-fill controls and liquid nitrogen supply Dewars are located 40 ft from the mag- net in a region adjacent to the experiment control room. The solenoid was energized continuously by the power supply -- no persistent switch was provided. The power supply is a solid state unit, rack mounted in the experi- ment control room. Data on liquid helium usage, magnetic field stability, and other operating characteristics are presented. *Work performed under auspices of USAEC. G17. Fabrication and Operation of Superconducting Beam- Transport Magnets Using Niobium Titanium .* ROBERT B. MEUSER, Lawrence Radiation Laboratory - At fields below 50 kG Nb-Ti conductor costs much less per unit current x length than its only competitor, Nb 3 Sn. For one to realize the potential lower cost of Nb-Ti beam- transport magnets the current density must be rea- sonably high and the fabrication costs low. To reduce fabrication costs, LRL has cooperated with a commercial organization in investigating the feasibility of using random-winding techniques to produce quadrupole and bending magnets from 0.030- in. -dia. wire. Models were made from copper and steel wire to develop winding tech- niques; it was found that a sufficiently high and suffi- ciently uniform space factor could be achieved. A superconducting dipole with a 3-in. -dia. aperture, a length of 18 in. , and a design field of 40 kG at 180 A has been constructed. The wire is bonded with epoxy and intrinsically stable conductor is employed. Two tech- niques were used in constructing bending magnets from 0.050 x 0.125 in. rectangular conductor. In one case, flat racetrack-shaped coils were bent to a saddle shape; in the other, the conductor was wound directly into its final shape. Two magnets with 5-in. -dia. apertures were constructed. One is 18 in. long and has a design field of 20 kG at 1000 A; the other is kO in. long and had a design field of !+0 kG. Experiences with the design, construction, and operation of the magnets are described. *Work performed under auspices of USAEC. Gl8. High Field Iron M agnets for Operation at Cryogenic Temperatures .* G.T. LAMBY, J.E. ALLIilGER AiO J.W. JACKSON, Brookhaven National Laboratory - Compact high field iron di- pole, quadrupole s.nd sextupole magnets, to be operated at cryogenic temperatures, will be described. Behavior at low temperatures of exciting coils of pure aluminum and other materials will be presented. Aberrations and excitation properties will be discussed, as well as applications to future accelerators and team transport hardware. "Work performed under the auspices of the USAEC. G19- .Adhesive and Insulating Systems for Cryogenic an d Superconducting Coils .* F. MARKLEY, A. McKAMEY AND J. — BIGGS, Argonne national Laboratory - The superconducting coils for the Argonne 12-ft. Bubble Chamber were assembled with an epoxy adhesive and a Teflon insulating intsrlayer. The design of a cryogenic adhesive system capable of taking the strains induced by temperature differentials or differences in thermal expansion coefficients is dis- cussed. Adhesive and insulating materials capable of appreciable elongation at cryogenic temperatures are ■ required. Commercial materials are compared. Mechani- cal test data on the adhesive shear strength at ambient and liquid nitrogen temperatures, on the effect of sur- face treatments for the copper and the Teflon, on the effect of the adhesive and insulation film thicknesses, and on the creep of thin, bonded Teflon films are pre- sented. Assembly procedures for the actual 15-ft. in- side diameter coils are illustrated. The epoxy, Teflon film adhesive system can be adapted to any cryogenic or superconducting coil using strip conductor, or to other cryogenic bonding problems such as the cryogenic titanium to glass bond for the photographic windows for the 12-ft Liquid Hydrogen Bubble Chamber. Some data from the win- dow bonding tests are presented to illustrate the effect of the coefficient of thermal expansion of the interlayer material. *Work performed under the auspices of the USAEC. G20. High-Quality Narrow Quadrupole Magnets .* K. H. LOU, J. M. HAUPTMAN, and J. E. WALTER, Lawrence Radiation Laboratory - Narrow quadrupole magnets of two sizes (8 i: -) 10 in. dia) were designed and are being built at Berkeley for use in Bevatron experiments . A prototype of the S-;r..- dia quadrupole was built,- and magnetic measurements of the line integral show the design to have very small harmonic content. For a gradient of 2800 gauss/in., measurements at a radius of 3-67 in. give harmonic content, expressed as per cent of the second harmonic, of 0.1% sixth, ^ 0.03f ; tenth, and 0.05% fourteenth. This paper discusses the magnet computational program (RNIL) that was used to develop the pole-tip contour and compares the calculated and measured harmonic values. Mechanical design and fabrication procedures are also described. *Work pe Commission rformed under auspices of U. S. Atomic Energy i on . G21. Design of the ISR Inflector . H. KUlffl, W.C. KID- DELKOOP, H. O'HANLON, C r RN, Geneva - Protons with a mo- mentum up to 28 GeV/c will be ejected from the CERH pro- ton synchrotron, transferred via two beam transfer chan- nels j each about 500 m long, and injected into each of the two intersecting storage rings being constructed at CEHN. At l/U betatron wavelength downstream of the in- jection septum magnet a fast pulsed inf lector deflects the team over a maximum angle of 2.5 mrad onto the in- jection orbit. This pulsed inf lector consists of two line -type magnets each 1.5-m long, which operate in ultra high vacuum. The C -shaped ferrite magnets have a gap width of UU.5 mm and a gap height of 20 mm. The useful magnetic field region is ! +0 ram wide. A prototype inf Tec - tor has been constructed consisting of all auxiliary electrical elements, one magnet and two UHV tanks. The 2.1-p.s magnetic pulses are generated by discharging a coaxial high voltage cable via a deuterium thyratron into the magnet and its matched terminating resistor of lU Q. The droop on the magnetic field flat top is 1% and transients on the flat top and after the pulse are about + 1%. The magnet has been tested at its maximum required operating voltage of 21.5 kV and at 25 kV in a vacuum of 10" 10 torr. Q22 . Design and Performance of the Orrnitron Septum Test Magnet .* K. HALBACK, D. T. SCALISE, ATiD E. H. HOYER, Lawrence Radiation Laboratory - The perturbation theory, design principles, design, and test data for a 1600- gauss dc septum magnet with a 0.020 x O.'f-in. septum are presented. To describe the effects on the fields of the non-uniform current distribution resulting from the high power density in a thin septum, conformal mapping tech- niques are used. It is shown that there is an optimum location for heat sinks, giving minimum field perturba- tions both inside and outside the septum magnet. Con- cerning the fringe fields outside the magnet at the ends, it is shown that they can be intrinsically avoided with the proper design, and that the end fields in the magnet are then purely two-dimensional and, therefore, calculable with conformal mapping techniques or two-dimensional mag- net codes. These design principles, as well as some ethers of minor importance, have been applied to the Oirjiitron test magnet. Its important design features are discussed in detail, and magnetic field measurements are presented. *Work performed under auspices of USAEC. G25. The Ul traf lector Current Switch . I .A. LAW AMD J .M . PATERS ON , Cambridge Electron Accelerator, H arvard University - To switch the CEA electron beam of up to 3 GeV energy into the CEA Bypass 1 it is necessary to generate in less than 150 ns an KKF of 2*400 arr.pere- turns in a magnet having an inductance of 1 ^H per turn squared, producing a field of about 2^00 oersteds in an aperture l/2 X 1 x 11 inches . A current switch having a 150-ns risetime and an indefinite on time with a com- bination of a thyratron to obtain fast riseti.r.e and an SCR to control the dc current has been designed, and is in use. The switch can be used in a pulsed mode to produce fast risetime field pulses between UOO and 2U00 oersteds as short as several milliseconds at a repetition rate of 1 Hz. 1 Hofmann et al, "The Colliding Beam Project at the Cam- bridge Electron Accelerator", Proc . 6th Int. Conf. on High Energy Accelerators , September 19&7. G26. A System for High Field Pulsing and Demagne tizing of Multipole Magnets in the AGS .* U. VOGEL , Brookhaven National Laboratory - A system is described where an ac generator is used to drive high oscillating currents into a load magnet. These currents decay to zero within a fraction of a second and can, therefore, be used for high field pulsing of multipole magnets in the AGS without affecting their remanent fields. The system makes use of the small leakage inductance of an ac gen- erator. Prior to pulsing, the generator is run with field coils powered. At the proper time and phase, the generator output is switched into the load magnet and at the same time the field coil current is let decay to zero. By proper matching, the peak currents obtainable are of the order of the generator short-circuit currents. Results of tests made on a 125-kVA variable frequency generator are presented and discussed. It is shown that in such a system it is possible to drive a few kilojoules into load magnets within the first quarter cycle at a frequency between 10 and 60 Hz. Transients in the power line feeding the driving motor are negligible, since the above energy burst of kilojoules is supplied by the inertia of the generator rotor. The relations between the generator and load-magnet parameters for optimum coupling are discussed. *Work carried out under the auspices of the USAEC. G23 . A Gradient Ferrite Pulsed Infle ctor for 130-i'eV Electrons . T. DICKINSON, Cam bridge Electron Accelerator . Harvard University - The injection path at the Cambridge Electron Accelerator requires a 10-mrad inflection to in- sert the 130-KeV electrons into the synchrotron orbit. The fast pulsed ferrite magnet described is in routine use as the inflector. The ferrite is shaped to provide the field gradient of 22> per inch required by the design of the injection transport system. The pulser uses a 50-ohm coaxial cable as a delay line. The 800-ns , 500-A pulse has a fall time of less than 100 ns, allowing a synchrotron orbit fill of approximately 85$. Electrical noise from the pulser is negligible outside the magnet tank and pulser cabinet. A summary of experience with the inflector is presented. C2U . The Design of Beam Inflector Magnets for Ultra - high Vacuum Operation . R. D. HAY, Cambridge Electron Accelerator - There is increasing need for beam steering magnets designed to operate at vacuum between 10"" and 10" 11 torr in storage rings or particle accelerators. Increased radiation damage resistance is also desirable from a reliability consideration. Presented are details and vacuum performance of: a high current density dc septum magnet; a laminated core ac septum magnet; and high frequency ferrite pulsed inflectors, both high and low voltage. All are designed to the stated requirements. Various materials and design approaches are described, with emphasis on low outgassing inorganic materials and well vented structures. G27. Slow External Beam Ejection Magnets and Power Supplies .* H. C. H. HSIEH AND A. V. S0UKAS , Brookhaven National Laboratory - Slow beam extraction at the AGS is based on a third- integral resonance scheme. The final step in the extraction process utilizes a two-mag- net system. The first consists of a thin-septum kicker magnet capable of 1 milliradian deflection and the second is a thin-septum ejector magnet system capable of pro- ducing a 20 milliradian deflection at a momentum of 30 BeV/c. The efficiency of extraction is directly related to the septum thickness; thus, one minimizes this dimen- sion subject to cooling limitations. The kicker magnet septum developed at Brookhaven is a 30-mil , 30- in. long edge-cooled type. The ejector magnet consists of three sections of total length ~ 7 feet and has two and three turns, water-cooled and insulated from each other with ceramics. The power supplies utilize series transistor bank regulators of 2000-A and 6500-A current capability for a pulse length of 600 milliseconds. The dynamic power range of the ejector power supply is greatly en- hanced by a liquid freon cooling system. The ratings are 50-kW continuous and 300-kW peak. Details of the protection circuits for both the magnets and power regu- lator systems are given. *Work performed under the auspices of the USAEC. G28. Development of the Floating Wire Method for the Control of Comdex Optical Systems . J. JAOUEN, J PIKfl AI;d D.T. THAN, CSF - Corbeville - The systematic develop- ment of this method, and especially of the wire stability has lead to improvements in the precision and simplicity of use, which are particularly interesting in the" case of complex systems as compared to complete field plotting and computer calculations. The following cases will be discussed: a) study of an achromatic system, b) use of stabilizing systems for complex systems, c) determina- tion of conjugate points of complex systems, d) measure- ments of the optical qualities of a high resolution ana- lyzer, e) measurement of the properties of quadrupole lenses . C-29 . Differential Analysis of Magnetic Field Measure - ments with Applications . JOMTHAH D. YOUNG, Lawrence Radiation Laboratory - This report describes the use of cubic spline fitting to compute, for the median plane (z = 0), the normal magnetic field component, B z (x, y, o) and its partial derivatives at specified mesh points (x-- , y.) from a set of measurements of B . The construc- tion and properties of the cubic spline fit are outlined. The results from the fit are used in interpolation and in approximating, off the median plane (for small z), the field components, B , B , and B z at a specified point (x , y„, z ) . The third order approximation makes rea- sonable the use of exact equations of motion in tracking charged particles through the magnetic field. In parti- cular, the applications of this process of differential analysis of field measurements for the Bevatron (Berkeley) are discussed. G30. Computer Solutions for Three -Dimensional Electro- magnetic Field Geometries . D. KELSON, H. KIM ML M. REI- SER, University o f Maryland - A computer program has been written utilizing the relaxation method for the solution of Laplace's equation in three dimensions. The program accepts boundary conditions of nonanalytic geometries and numerically solves' for the potential at all points on a three-dimensional mesh. Unique features of this program include machine-coded subroutines for high speed conver- gence and the capability of an unlimited number of mesh points . The program is currently running on an IEM 360 and has been used to solve problems involving more than a million mesh points . G33- Investigation of the Characteristics of Ceramic Capacitors for Synchrot r on Kicker-Magnet A b dication . DAVID L. SMART AND BOB H. SMITH, Lawrence Radiation L aboratory - The inherently low inductance, geometrical simplicity, and low manufacturing costs of ceramic capa- citors make them attractive for kicker -magnet pulse lines, but their piezoelectric and dielectric hystereses compli- cate their use. The piezoelectric characteristic causes mechanical fracture of the ceramic if the electrical gradient is too high; the dielectric hysteresis limits the repetition rate because of the associated tempera- ture rise. The voltage and temperature capacitance sen- sitivity does not appear to present a serious problem in this application, because the permissible gradient and temperature is limited by the other factors affecting reliability. These characteristics were measured for the most commonly used ceramics, and the results tabula- ted. From these data one can choose the best ceramic composition. The choice depends upon the repetition rate, pulse shape, and geometrical considerations of the capa- citor. This study shows that properly designed ceramic capacitors are superior to other types for a kicker-magnet pulse line when the pulse length is sufficiently long to preclude use of a distributed line and when the rise and fall times are sufficiently short to make lead inductance significant. *Work supported by the USAEC. G3'+ • Electrical Tests of Zero Gradient Synchrotron Magnet Coils . KOSTAS BURBA AMD ALFRED ROHRMAYER, Argcnne Rational Laboratory - A survey of the 16 most common electrical tests is discussed; and their applica- tions to the Zero Gradient Synchrotron (ZGS) ring magnet, extraction, auxiliary, beam line transport, spark chamber, and bubble chamber magnet coils are described. Type, sequence, and timing of various tests during coil manu- facturing, acceptance, and operational periods are out- lined. Detailed information is given on test methods, values, equipment, procedures, and limitations. The de- descriptions of the induced and applied voltage tests for detection of shorted turns and the conductor joint tests are emphasized, since the methods applied differ from the tests applied in industry and other laboratories. Main- tenance and trouble -shooting procedures are mentioned. Work performed under the auspices of the USAEC. G31. Two-Dimensional , Uniform Current Density, Air- Core Coil Configurations for the Production of Specified Magnetic Fields .* G. H. MORGAN, Brookhaven National Labor - atory - A computer program has been written which can compute the two-dimensional, uniform current density, air-core coil configuration needed to produce a specified field (e.g., uniform field or quadrupole field) in simply- shaped regions such as ellipses, when the inner boundary of the coil coincides with the periphery of the region. The procedure is to expand in a Fourier sine series a correction curve to an initial approximate outer boundary. *Work performed under the auspices of the USAEC. G32. Iron Magnets Without Air Gaps . G. PARZEN, Brookhaven national Laborator y - It is sometimes desir- able to fill the air gap of a conventional iron magnet with iron. In such a magnet the magnetic field depends very strongly on the saturation of the iron. The prop- erties of such magnets were studied with the aid of a mesh-iteration magnet program. Results of the study are given and the techniques are described. G35- Experience with Aluminum Coil Mag nets. EDWARD ROSKOWSKT, Stanford Linear Accelerator Center - In the magnets where high current density within the coil area is not required, the use of extruded aluminum conductors can provide substantial savings in conductor and coil fabrication costs that more than offset the cost of addi- tional iron required. Computer programs indicate that much can be done to minimize the iron required by making the coils into so-called "T" sections. Solutions to problems unique to the use of aluminum conductors are described. Two years experience with the use of water- cooled aluminum conductors in a mixed copper and stain- less steel water distribution system shows no discern- able corrosion effects on the aluminum conductors, the copper, or the stainless steel. Work performed under the auspices of the USAEC. G36 . The Effect of Distorted Voltages in Experiment Areas and Sug gest ed Improve ment::.'' ALFRED ROHRKAYER, JOSEPH R. STAPAY, AMD ARNOLD G. VANDERFTUGHT, Argonne National Laboratory - Most beam transport magnets in accelerator experiment areas are supplied by SCR-con- trolled power supplies. These cause notches in the ac supply voltage effecting the operation of various elec- tronic equipment supplied by the same bus. The effect of voltage distortion on a representative cross section of electronic equipment has been investigated, and the limits of acceptable voltage distortion have been estab- lished. The voltage distortion and the interference to equipment can be reduced by proper system planning, such as providing separate equipment or instrument bus- ses, and by redesigning power supplies, such as provid- ing 12-v>hase instead of 6-phase rectification. It is also possible to improve the wave -shape of the voltage in existing installations and to eliminate the effect on equipment performance. This would require to supply each SCR-controlled power supply in series with a choke and to arrange filtering equipment in shunt with this choke. In most cases, a single capacitor will suffice to provide adequate filtering action. Oscillograms are included showing the distorted voltage and the voltage obtained with the suggested arrangement. *Work performed under the auspices of the USAEC. G38. Temperature Distributions, Heat Transfer and Resulting Life Expectancy of Transformer Windings .* C. A. HARRIS AND D. R. WALZ , Stanford Linear Accelerator Center - The subject of this presentation is the trans- former windings of the SLAC 3.4-MW power supply used to operate bubble chamber and spark chamber magnets. The unit had a long-standing history of overheating which was cause for a detailed examination of the tem- perature distribution in the windings. Data are given that relates the average and maximum temperatures as calculated for the windings of a 2000 KVA dry-type rec- tifier transformer with the measured temperature rise in the as-built transformer. An estimate is made of the life of the transformer based on calculated temperatures and is compared with the actual service life at which the transformer failed. Methods to reduce temperatures are examined. It is shown that for this particular trans- former there would have been no practical way to cool the windings adequately to maintain its original ratings. The presentation should serve as a guide for calcula- tion, design, and examination of other transformers. It should also emphasize the importance of thorough analyt- ical investigation of previously untested designs. Costly misjudgments may thus be avoided. *Work supported by the USAEC. G37. The Power and Cooling Interconnection of the 200 - GeV Synchrotron Magnets . J. A. SATTI, National Accelerator Laboratory - The main synchrotron enclosure will be about 1-1/4 miles in diameter. Ninety percent of the circum- ference will contain few components other than focusing and bending magnets, so that the system for connecting the power and water to these magnets is designed to re- quire a minimum of maintenance. The magnet power supplies and low-conductivity water circulating systems are loca- ted in 24 utility buildings spaced uniformly around the ring. For the bending magnets, 4-in. copper pipes serve as current-carrying bus as well as cooling water supply and return. Smaller copper pipes similarly serve the quadrupole focusing magnets. Each quadrupole magnet or pair of bending magnets is connected to the bus system by three copper pipes less than an inch in diameter, two of which carry current. The magnet coils each have several parallel cooling passages interconnected by an integral manifold with insulation provided by ceramic tubes. All connections in the cooling-bus system, the connections to it, and connections within the magnet coil manifolds are either brazed or welded. Semiautoma- tic pipe welding and cutting equipment will be used to install and remove magnets. ROUND TABLE DISCUSSION G-39- Round Table Discussion of Heavy Ion Accelerators. R. M. MAIN, Lawrence Radiation Laboratory; J. A. MARTIN, Oak Kidr;e National Laboratory; P. H. ROSE, Hi^h Voltage Engineering Corporation; C. SCKMELZER, University of Heidelberg. Moderator: R. S. LIVINGSTON, Oak Ridge National Laboratory. INVITED PAPER HI. Computers in Accelerator Control Rooms - A Personal Appraisal .* M. Q. BARTON, Brookhaven National Laboratory - Several synchrotron laboratories now use digital computers to monitor many accelerator performance parameters. Closed orbit shapes, for example, are now available in a few pulses. Experiments have also been performed on using computers for closed loop adjustment of critical accelerator parameters. The implication of these possibilities toward the next generation of accelerators are discussed. The requirements on computer hardware and supporting staff for implementa- tion of a useful program are also discussed. ♦Work performed under the auspices of the USAEC . INVITED PAPER H2. Beam Detection Using Residual Gas Ionization .* W.H. DeLUCA, Argonne National Laboratory - The nondestructive beam detector systems originated at Argonne National Laboratory allow continuous measurement of the proton beam posi- tion and beam profile in the Zero Gradient Synchrotron during the accelerating and targeting cycle. Nondestructive detection is accomplished by collecting the ions produced by the proton beam ionizing residual gas in the vacuum cham- ber. The amplitude of the electrical currents obtained by collecting these ions onto a variety of electrodes depends on the distribution of the protons in the beam. The characteristics of the electric signals make them suitable as inputs to computer systems. Both analog and digital techniques have been used to determine beam position and profile. These beam detection systems have been used for measuring the properties of the 50-MeV beam between the injector linac and the synchrotron ring, for studying the steering and radial growth of the size of the beam during acceleration, and for measurements during the targeting sequences. *Work performed under the auspices of the USAEC . H3-t On-Line Computer Monitoring and Optimization of a Multiple Target Proton Beam Line . F. HORNSTRA, JR., AND R. E. SCHERR, Argonne Rational Laboratory - Operation, tuning, and monitoring of the multiple target EPB at the Zero Gradient Synchrotron (ZGS) is described. Instrumen- tation presently installed permits continuous, nonde- structive, quantitative, on-line computer monitoring of beam spot size, position, and intensity at each experi- menter's target or any desired location. The capability of a rapid emittance measurement is also provided. This measurement serves as input to computer programs, de- scribed elsewhere, which calculate the emittance and the necessary quadrupole settings for required beam profiles along the beam line. As a check, the resulting beam profiles are instantly measurable at appropriate loca- tions and any necessary final adjustments to provide more exact required conditions are then accomplished. *Work performed under the auspices of the USAEC. H^ . t Capabilities and Uses of a Graphic Display Sys - tem as an Interface Between the ZGS Computer and the Human Operator .* L. G. LEWIS, M. J. KNOTT, R. GEORGE, C. S. CHIEN, A. VALENTE, AND G. GUNDERSON, Argonne National Laboratory - The control computer system at the Zero Gradient Synchrotron (ZGS) contains a 20-in. cathode- ray graphic display system that can generate points, vectors, and characters. A variety of software routines have been written to operate the ZGS monitor on-line to obtain the required data, to perform the necessary cal- culations and to generate the specific display patterns. Two dimensional displays describe accelerator parameters that are functions of time, or of a space coordinate, or of a second machine parameter such as ring magnet field. "Three dimensional" displays (isometric), such as tune as a function of radial position and of ring magnet field, can also be generated. Many of the display patterns can be updated promptly so that the operator can follow the changes during an adjustment or optimization procedure. Experience shows that this display system can present complex information to, the ZGS operator in a form that is easily understood. Permanent records of display in- formation can be made by photography, by using the 30-in. X-Y plotter system, and by using the line printer. A variety of examples will be discussed. *Work performed under the auspices of the USAEC. H5«t Instrumentation and Control of AGS Slow External Beam .* J.D. FOX, G.W. BENNETT, G.S. LEVINE, R.J. NAWROCKY, L .E . REPETA AND A .V . SOUKAS , Brookhaven National Labora - tory - Instrumentation for the slow external beam includes counter telescopes, insulated plates, spill counters, Cerenkov counters, fluorescent screens viewed by tele- vision cameras, and secondary emission chambers. Counter telescopes and directional Cerenkov counters are used to measure scraping of the beam at critical places . The over- all radiation background has been sufficiently low so that we have been able to operate counter telescopes without jamming and without any evidence of loss of sensitivity due to radiation damage. Beam profiles have been measured by accurately positioned insulated fingers and by radio- autographs of irradiated foils . Time structure of the beam is measured by spill counters and by insulated plates . Signal from a pair of insulated plates is used to generate a correction field in a ferrite core steering magnet to counteract angular beam modulation caused by momentum spread and ripple in the ejection magnet. Intensity is measured by secondary emission chambers which are cali- brated against polyethylene foil activation; the calibra- tion has remained reasonably constant over a wide range of beam intensities. *Work performed under the auspices of the USAEC. H6. The Use of Computer Developed and Generated Dis- plays in the Monitoring and Control of Accelerators . R. FRANKEL, Brookhaven National Laboratory - At the AGS, our PDP-8 computer system possesses the ability to per- form simple calculations in essentially real-time and to immediately present this normalized or processed infor- mation to the accelerator operator rn either numerical or graphical form. Graphical information is displayed in a flicker-free manner on any standard oscilloscope by employing the computer's interrupt facility and a digital/analog converter. Alpha-numeric data or non- time dependent functions are readily presented with a software character generator data set, two digital/ analog converters and an xy storage oscilloscope. Thus, special character generator sets or high cost cathode ray tube display systems are not required to provide the benefits of more sophisticated presentations of opera- tional parameters. The system has been used to present such complicated and diverse displays as the frequency distribution of intensity, a quality control plot (including range limits) of accelerator efficiency, the accelerator's equilibrium orbit, and the pulse-to-pulse ejection efficiency of our slow extracted beam. *Work carried out under the auspices of the USAEC. H7« Improving Information Exchange Between the AGS and Its Experimenters .* A. R. WATTS AND G. W. CORNISH, Brookhaven National Laboratory - The increasing number of concurrently operating experiments and our expanding experiment areas are creating a need for more effective communications between the AGS and its users. With regard for cost, flexibility, and our often very noisy environment, a visual information network has been de- vised to complement our public address, experiment hall status-board, and interphone communications system. A closed circuit television system and associated annunci- ator panel are used to provide each experimental group with machine status, performance data, and other infor- mation of interest. Each experimenter sends coded opera- tional status information to the control room where it is processed and displayed. Relevant machine and experi- menters' information is at the same time sent to our computer which periodically scans and records this infor- mation so that it may be analyzed and presented on com- mand. The details of this "network" are described, and our criteria for selecting information to be transferred in this manner is discussed. Work performed under the auspices of the USAEC. H8. Computer Controlled Energy Spread Measurement at the CERN PS Linac . U. KRACHT, A. VAN DER SCHUEREN, U. TALLGREN, P. TETU, CERN. Geneva - A new method of energy spread measurement is described which permits a quick evaluation of the percentage of the PS linac beam inside the acceptance range of energy spread for the synchrotron. The execution of the measurement, for which a minimum of two beam pulses are lost, is under control of the PS Con- trol Computer, IBM 1800, and makes use of two beam slits, a triplet lens, and a beam deflecting magnet. The result of the measurement is simply obtained as the ratio of two beam current transformer readings. These are read in the beginning and at the end of the beam pulse and the computed results together with other Linac machine parameter readings of interest, such as rf tank levels, are displayed on a TV -screen at the linac and in the PS Main Control Room. On request, a print -out of the results can also be obtained. Before executing the measurement, the computer program checks the status and levels of important parameters and in case of malfunctioning warns the operator with a diagnostic message on the TV-screen. H9- Fast Automatic Beam Momentum Analyzing System for a 300-nsec, 300-Ampere, 3 to 6-MeV Electron Beam .* J. F. RYAN, W. A. SHERWOOD, AND M. E. SMITH, Lawrence . Radiation Laboratory, Livermore - A wedge-shaped electro- magnet is operated analogous to a motor driven light - optical prism monochromator . Magnetic field values and electronically processed analyzed beam signals are con- veniently registered by an X-Y plotter. A complete time- integrated beam momentum spectrum, defined by 120 data points, can be printed out in less than SO seconds. Sys- tem AP/P is less than 0.002. *Work performed under the auspices of the USAEC. H10. Beam Matching, Steering, and Design Using a CDC- Q 2^, and Oscilloscope, and Programs Developed at Argonne National Laboratory . STEWART MARCOWITZ, GEORGE CONCAILDI, AND RICHARD GEORGE, Argonne National Laboratory - Computer programs have been developed at ANL to match given input beam phase space conditions to desired output conditions with up to six quadrupoles. An oscilloscope will produce beam envelopes, trace rays, or produce phase space diagrams at given locations in a much larger simulated beam system. Provisions are avail- able for treating off -axis and off -momentum beams. Ele- ments include slits, "drift space, quadrupoles, and bending magnets. The phase space configuration accepted by a system with displaced elements, off -momentum beams, asym- metrically placed slits, and element apertures can be displayed on the oscilloscope. These features have been used to design experimental beams, tune the Zero Gradient Synchrotron (ZGS) external proton beam, and steer the ZGS external proton beam. Excellent agreement has been found between the program predictions and actual beam parameters. Measurements of beam spot sizes at one or more locations have been used to compute beam phase space conditions which are subsequently used in the other pro- grams. The programs used have been titled WIEMNY, MATCH, and QUISP. *Work performed under the auspices of the USAEC . Hll. A Digital Resonance Control System for the Drift - Tube Linac - JOHN B. SHARP AND GEORGE R. SWA IK, Los Ala - mos Scientific Laboratory - A resonance control system for the drift-tube linac portion of IAKPF has been pro- posed; it incorporates a digital computer in the closed loop. The inherent computational capabilities of the digital computer allow considerable flexibility in the digital controller. Nonlinear functions of various feed- back variables and their derivatives, which are easily implemented on the computer, can improve the steady-state and step responses of the system. The long thermal time constants in the system make conventional compensation techniques hard to implement with analog circuitry, but relatively simple with digital software. An experimental resonance control system for a U-ft drift-tube linac model has closed the loop through an SEL-810A computer. The model has separate water-cooling systems for the tank wall and the drift tubes. The necessary state variables from each system are fed back into the digital controller, which generates from this data the number of pulses nec- essary to drive valve-positioning stepping motors, there- by regulating the amount of cooling water entering the system. This setup also allows a study of the effects on the control system of a longer drift tube tank by inserting into the software appropriate time delays. ♦Work performed under the auspices of the USAEC. H12 * Stimulation and Measurement of Radial Betatron Oscillations in the Bevatron Using the rf Accelerating System.* K. C. CREBBIN and F. H. LOTHROP, Lawrence Radiation Laboratory - Recent activity in resonant ex- traction of the circulating proton beam at the Bevatron spurred interest in accurately measuring the radial beta- tron-oscillation frequency. This paper presents a dis- cussion of the techniques and hardware employed in the project. Calculations indicated that it would be prac- tical to use the existing rf system tuned to the betatron oscillation frequency for excitation of the desired oscil- lations. In practice, the measurement is made during a period of constant magnetic field, when the accelerating rf may be turned off and the beam allowed to coast at a constant radius . The frequency is changed to the beta- tron frequency, and the rf system is turned on again. The proton rotational frequency and the betatron oscil- lation frequency were measured with the aid of a small digital data processor. Our system allows dynamic, on- line, presentation of beam radius, betatron frequency, and rotational frequency to a precision of about one part in 10,000. ♦Work performed under auspices of the U. S. Atomic Energy Commission. HI 3. Controls for the CERN Intersecting Storage Rings . 0. GROBNER, D. NEET, P. RIEBEN, B. SA3NELL, G. SCHAFFER, R. SCHOLL,* K. UNSER, P. WOLSTENHOLME, CERN, Geneva - The paper summarizes the requirements and present work on the design and construction of the control system for the CERN Intersecting Storage Rings (ISR). Details are presented of the controls for the various beam transfer channels required to link the CER1I Proton Synchrotron to the ISR and to a new beam switchyard and experiment area for use of fast or slow ejected beams. The factors which dominate the layout of the ISR control system are dis- cussed; the function and design of major parts, such as beam transfer instrumentation, vacuum controls, personnel radiation protection and the control computer system are described. *0n leave of absence from SLAC - Stanford University. HI 1 *. Computer Control of the PPA Synchrotron . J. HEUNESS, M. ISAILA, K. KOEPKE, D. SOBER, W. YANG, Princeton -Pennsylvania Accelerator - An active program to do on-line machine control and tuning is currently in progress. The projected system will also. perform data logging and correlation. Single variable self -correct- ing programs have been written and successfully used to control both injection and spill. Closed loop control will be applied to injection, field trimmers, rf para- meters and spill control. The projected use of a PDP-9 with a direct memory access interface is described. Present accomplishments as well as future plans are detailed. H15. SIAC Accelerator Control Computer . DARYL REAGAN, Stanford Linear Accelerator Center - A digital computer system is being installed in the SLAC accelerator control building to assist the operators who monitor and control the accelerator proper. Initially, the computer will be programmed to recognize losses of klystrons, which result usually from temporary malfunctions, and in each case to select and switch on a suitably programmed re- placement unit. As more equipment is installed and programs are developed, the computer will take on a variety of jobs. It will prepare and analyze records of accelerator system and component performance. It will assist in setting up new experiments. It Will perform control operations where rapid response is desirable. It is planned that the computer will even- tually form part of a system in which all accelerator and beam switchyard controls are manipulated from one control center. Hl6. The Process Control Computer at the CERN Proton Synchrotron: Its Application in the Operation of a Fast Ejected Beam . H. VAN DER BEKEN, D. R. MACHEN,* J. H. B. MADSEN and CH. SERRE, CERN, Geneva - In 1966 the decision was made to acquire an IBM 1800 for assisting, and possi- bly optimizing, the operation of the PS. We felt that we should start right from the beginning with computer applications that involve acquisition as well as control settings . An existing system for remote control of dc power supplies for the ejected beam transport was easily adapted to the computer requirements (control via a fre- quency multiplexed system) . The following tasks are per- formed by the computer for the fast ejected beam: (l) to measure and to keep the currents in the beam transport elements constant; (2) to furnish a log on the ejected beam, store a reference log and provide, on request, a variation log; (3) to search for the beam position on the external target that gives a maximum secondary parti- cle production. This task is done via a scanning and optimizing program which displays the progress of the procedure visually on a CRT. Details on the operational features, the hardware and the software are provided, together with illustrations on the results obtained. *Presently at Los Alamos Scientific Laboratory. H17- Digital Control of Bevatron External Proton Beam Transport Magnets ■ DOM EVANS, Lawrence Radiation Labora - tory - A computer-based, digitally structured, data ac- quisition and control system has been developed for the purposes of on-line programmed control of external beam transport magnets at the Bevatron. The control algorithm achieves flexibility to accommodate all possible modes of Bevatron operation by separating the operating cycle of the accelerator into several zones . This method allows independent processing of Bevatron field within each zone, and the introduction of zone-related time-variable functions in each of the magnet currents . Evolution of the hardware is discussed, together with consideration of employing small computers for each well-defined project, over a time-shared single large computer. The technique utilized to provide time-sharing of peripheral hardware between small computers is described. Pertinent details of methods used to achieve noise rejection in data trans- mission, both analog and digital, are examined. Communi- cation between digital systems and human operator is dis- cussed in terms of minimizing the number of operator responses required to establish a series of functions to be performed by the system. Hl8. Zero Gradient Synchrotron Experimental Area Control System .* EARL W. HOFFMAN, PAOLO MARCATO, DAVID H. NORDEY, LEROY G. PARSLOW, AND FRANK L. SCHWEINGRUBER, Argonne National Laboratory - A control system has been installed in the experimental area at the Zero Gradient Synchrotron. It is presently being used to monitor and control the magnets and other beam line components in the separated beam lines to the hydrogen/deuterium and freon/propane bubble chambers. This has made possible the reassignment of control room personnel and the more efficient operation of the bubble chambers. Equipment is being added to extend the control capabilty to other beam lines and buildings in the experiment area. Facili- ties are also being added to allow the system to act as a source of information for analysis of experimental data through both computer interconnection and tape storage. The system is operated in a foreground/back- ground mode so that all experimental beam line monitor- ing and control operations are fully protected from operator error. This allowed the system to be useful to the physics program within a month after the computer delivery while also allowing the assembling and checkout of more advanced programs. *Work performed under the auspices of the USAEC. H19. Computer-Control for the Maryland Cyclotron . J. ETTER, K. JENKINS AND D. NELSON, University of Mary- land - The Isochronous Cyclotron at the University of Maryland has been designed to allow computer control of all machine operations in a manner that permits unique operational flexibility. Digital control lines, 16 bits wide, run from various devices in the laboratory to a central multiplexor unit. From there, they are routed to either the operator's console or to a computer data bus . The data bus is attached to a small control com- puter which will be interfaced to an on-line IBM 36O/I+I+, and will be capable of reading and setting machine con- trols as well as communicating with the machine operator. The software of the control computer will consist of a highly simplified time sharing system which will coor- dinate the execution of several independent software modules called 'tasks'. Each task will pertain to a particular control function and the operating system will 'time share' among several tasks, allowing them to run concurrently. It is intended that this system will greatly simplify normal operations and allow the operator greater freedom from menial chores . A Mult i -Programming Executive System H20. OMNIBUS for the Zero Gradient Synchrotron Control Computer . 1 M. KNOTT, A. BRESCIA, AND A. VALEMTE, Argonne National Laboratory - As the digital computer undergoes increasing utilization as an on-line evaluation and feedback control device for an accelerator, it becomes necessary to provide it with a multi -programming executive software system. The system should be capable of accommodating several on-line control functions simultaneously so that these functions can be developed and utilized independently. The system should also provide for general -purpose off- line utilization such as new program development to pro- ceed simultaneously with and unimpeded by the continuous operation of the accelerator. OMNIBUS, the multi-pro- gramming executive system now in use with the Zero Gradi- ent Synchrotron control computer facility, incorporates these features and several others not found in commer- cially available multi -programming systems. OMNIBUS obtains data for the various programs from locations and at times requested by the programs and also provides the control link either by modifying the program stored in the timing system of the synchrotron or by direct trans- mission of timing pulses or digital information to the accelerator. The system also provides for operator modi- fication of the various programs and communications with them without interrupting their on-line control or moni- toring functions. # Work performed under the auspices of the USAEC. H21. Real-Time Executive for a Small Computer System .* C. STEWART, Brookhaven National Laboratory - Our PDF -8 system, consisting of two processors, a disk, a tape drive, and numerous devices interfacing with the AGS, has access requirements running from microsecond real- time to input/output jobs which may run for fifteen min- utes. An executive is described which allows programs to time-share the processors on a 16 millisecond exchange-jump basis. This executive also supervises time- sharing of a resident utility system package which is also described. Two job stacks are provided — one calls resident programs at preselected millisecond intervals, and the other services an 8-exchange -point list of time- shared programs. A disk is used for general purpose, input/output, and for program library service. Programs may be called from this disk library via programs running in the PDP-8 or from the on-line teletype. A floating- point arithmetic package is available and shares core with other programs by means of a rollin/rollout facility. *Work performed under the auspices of the USAEC. H2U. PCM Data Transmission System Using; Split Phase Code .* EZRA C. BUDGE, T Los Alairos Scientific Laboratory - The LAMPF control system specifies transmission of both data and timing signals between the control room and the local control points throughout the machine for data collection and equipment control information. A balanced system is used to reduce noise pickup. The transmitter receives a timing pulse train and the digital data in a "non return to zero" NRZ format. The two sig- nals are combined to form a split phase code and trans- former coupled to the transmission line. The receiver uses a minimum energy content circuit (integrator) pre- ceding the decoder to reduce noise sensitivity. The number of timing pulses in the incoming pulse train is known, as is the time duration of the transmission. This information is used to further reduce the proba- bility of error. Farity checking is also provided. The system is described and results of experiments on the system reported. *Work performed under the auspices of the USAEC . i On loan from Technical Services Group, EG&G, Inc. H22.t A Compact Data Acquisition and Control Terminal for Particle Accelerators . *D. R. MACKEN, R. A. GORE, AMD D. W. WEBER, Los Alamos Scientific Laboratory - The pres- ent trend toward automation of information processing in particle accelerators dictates the need for a thorough evaluation of the method used in collection and dissemi- nation of this information. A compact, remote terminal for use in automatic data acquisition and control of par- ticle accelerators will be described. The terminal may be controlled either by special -purpose digital logic or by a central control computer. Interfacing to the vari- ous accelerator equipment is provided through analog and on-off control and monitoring modules. The detailed de- sign of the logical portion of the remote terminal, in regard to data format, instruction, and command decoding, will be discussed. The method of selection of the ap- propriate module interface for completion of the desired function will also be treated. In addition, the equip- ment-interfacing design criteria resulting from actual implementation on accelerator devices will be discussed. Finally, a report will be made on the operating experience gained through use of the remote terminal interfaced to a high intensity proton source. ♦Work performed under the auspices of the USAEC. H23« A Versatile Technique for Interfacing a Control Computer with Remote Data Acquisition and Control Sta - tions along Particle Accelerators .* F. DUNCAN TERRY, Los Alamos Scientific Laboratory - Interfacing a control computer with remote Data Acquisition and Control Stations (DACS) along particle accelerators presents a number of problems and several possible basic design alternatives. Selection of the best overall approach requires a trade- off between performance, reliability, and cost. The tech- nique selected for use in the Los Alamos Meson Physics Facility will be discussed. The system requires a mini- mal cable plant while maintaining high-speed response to computer instructions. No special adjustments are re- quired to compensate for the variable propagation times to and from randomly spaced remote DACS. The system allows the computer to address, simultaneously, any group of remote DACS desired. The group is software -controlled and may be composed of an arbitrary assortment and num- ber of DACS . The computer need not await the rela- tively slow responses of controlled hardware such as relays. The system has a memory to buffer data transmit- ted from the remote DACS to the computer. Information formats and a detailed block diagram of the system logic will be discussed. System modifications derived from operating experience on the Electron Prototype Accelerator (EPA) will be included. H25- Multiplexing, Digital Beam Information Signals to Accelerator Users .* F. GREELEY, M. KNOTT, L. LEWIS, C. SW030DA, Argonne National Laboratory - As the list of digital data signals required by accelerator users grows, it becomes more economical to use serial -input parallel- output multiplexers at the users control station than to increase the number of coaxial cables used to supply parallel data. Increasingly, on-line computers are used to control and monitor accelerators, and since the digit- al beam data is naturally generated in a serial mode, the multiplex receiver becomes doubly desirable. The Zero-Gradient Synchrotron (ZGS) at ANL has built such a receiver named CUPID, an acronym for Computed Pulse Information Decoder. Using two lines of serial input, the receiver generates one counter master reset pulse and input signals for up to thirty-one counters. The paper includes block diagrams, system description, and prac- tical application data. *Work performed under the auspices of the USAEC. H26. Application of Telephone Crossbar Relays to Computer Control of a Particle Accelerator . JAMES W. DAVIS, WARREN L. DEXTER, AND BOB H. SMITH, Lawrence Radiation Laboratory - A prototype automatic control system using crossbar relays for switching was built for experimental study. Eleven sets of these highly reliable and inexpensive relays can provide computer or manual access to the control of 10,000 magnets or other regulated systems. The system consists of a computer, several manual -control panels, a set of crossbar relays, digital regulator references and actuating devices, and a corresponding readback system. The manual -control panels contain an address keyboard, which controls the crossbars, and a data-entry keyboard. .The data are routed to the desired regulator reference or actuator. Since any number of manual -control panels may be used, each maintenance specialty can have its own control of the accelerator on "down" days. For automatic operation the computer simply replaces one of the manual -control panels. The coil-to-contact isolation in the regulator reference chassis and digital read-out systems provide essentially infinite noise isolation between the acceler- ator and the control system. Without the computer the cost is comparable to a conventional manual -control system. Design considerations of the special devices which are unique to this type of control are included. *Work supported by the USAEC. "Work performed under the auspices of the USAEC. H27 • Automated Multiple-Beam Charged-Particle Trans - port System ." WARREW L. DEXTER, Lawrence Radiation Labo - ratory - A novel automated magnet switching system has "been devised whereby power for beam-transport magnets of multiple -beam arrays can be supplied by common power supplies, thereby reducing the power-supply costs to that of a single beam line. The heart of the system is com- pact and inexpensive computer- or punched -card-operated reversing and selector switches that can switch kilo- amperes. The complete system and the switches are described in detail. *Work supported by the USAEC . H28. Ion Source Control Through High Voltage Isolation Distances Utilizing Photon -Coupled Solid State Devices .* ROBERT L. BENNETT, University of Wisconsin - Low power photon -coupled semiconductors may be utilized to control a pulsed ion source operating at a high potential isolated from ground. If efficient optical coupling is achieved, a distance capable of standing off as much as a megavolt may be possible. Various methods of optical coupling may be used, such as lens or mirror focusing or by transpor- tation of the light beam through an optical fiber bundle. The latter method is presently being used in a system designed for Dr. C. D. Curtis at NAL. The isolation distance for this ion source system will stand off 150 kV. Operation of the ion source at this distance has been satisfactory. Preliminary tests indicate that the iso- lation distance may be doubled with no deterioration in performance merely by increasing the optical fiber bun- dle length. Minor circuit modifications, including a slightly higher power level light -emitting semiconductor diode and an appropriately longer optical fiber bundle, should extend the potential isolation distance to the 1-MV goal. The semiconductor light source is a pn junc- tion gallium arsenide light -emitting diode. The light detector is a NPN planar silicon phototransistor . *Research sponsored by the USAEC. H29. Linear Light Link Data Transmission .* EZRA C. BUDGE, t Los Alamos Scientific Laboratory - A discussion of a digital data transmission system has been presented.! Many signals from the ion source in the high voltage head will be digitized and transmitted via a light link to the control point. However, wide bandwidth signals are difficult to digitize, transmit, and reproduce; therefore, a linear transmission system using light links to cross the high voltage interface has been de- veloped. The transmitter and receiver were aligned in the usual laboratory environment. A triangular wave- form was used to test linearity and a fast rising pulse was achieved at a distance of i+0 ft between transmitter and receiver. The system is described and results of experiments with the system reported. * Work performed under the auspices of the USAEC. t On load from Technical Services Group, EG&G, Inc. 1 Ezra C. Budge, IEEE Transactions on Nuclear Science, NS-li+, No. 3, 107 1 * (1967). H30 . The Measurement of AGS Spacial Beam Density Dis - tributions by Means of Flipping Targets . U. VOGEL, Brookhaven National Laboratory - A development of the technique of monitoring the spill off targets sweeping across the AGS proton beam is presented. To achieve minimum interference with the beam and adequate accuracy, stems of 20-mil beryllium wire have to be swept across the beam within milliseconds. This was achieved by mounting an inertial linkage mechanism on a standard target motor. The mechanism links two beryllium wire stems so that they sweep the beam in mutually perpendi- cular paths. Two orthogonal beam profiles are thus generated. The sweeping speed is obtained from high angular velocities of the wire stems. Due to the dynam- ics of the linkage arrangement, the above velocities are several times higher than the angular velocities of the standard target motor. A description of the above and results of tests made on the bench and in the AGS ring are presented and discussed. *Work performed under the auspices of the USAEC. H31- The CPS Gas-Ionization Beam Scanner . C. D. JOHN- SON and L. THORNDAHL, CERN, Geneva - A non-destructive beam scanner was installed in the CPS ring early in I968. Deriving a signal from the electrons liberated by the proton beam from the residual gas in the vacuum chamber, and using a crossed electric and magnetic fields system of electron collection, the scanner gives the projected proton density distributions in the horizontal and verti- cal planes. Spatial resolution is better than 1 mm. An important feature is the use of a single collector which receives electrons from a slice of the beam close to the zero equipotential surface. The electric equipotential surfaces are parallel to the proton beam axis and scan- ning is achieved by displacing these equipotentials later- ally in the region of the beam. In particular, the zero equipotential, which always passes through the detector, is scanned right through the beam. Trials at scanning frequencies up to 5 kHz and pressure around 2.10" 6 Torr (nitrogen equivalent) have yielded some interesting results. A double beam is seen under certain conditions on the 'flat top' at 19 GeV/c . Another application is to the study of beam dimensions during the first few ms after injection. Further refinements include the installation of an electron multiplier to permit a lower pressure limit and an increased scanning rate, around 1 MHz, re- vealing coherent beam envelope oscillations. H32. Beam Profile Monitors for Fast and Slow Extrac- ted Proton Beams . D. A. G. NEET, CERN, Geneva - Two types of beam profile monitors, based on the principle of secondary emission (SEM), and some work on beam observa- tion screens made of inorganic material will be described. They will be used for emittance measurements, for beam matching, and in general for adjusting the beam transfer system of the CERN - Intersecting Storage Rings. The first type SEM profile monitor consists of a grid of 15 horizontal and 15 vertical narrow foils, which together with the necessary electronics provide quantitative sig- nals on the beam intensity profile. The second type con- sists of two SEM probes, driven by stepping motors. Each probe is programmed either to find the horizontal and vertical edges of the beam, or to make a plot of the intensity distribution. The paper also describes inor- ganic luminescent beam observation screens, which are suitable for ultra-high vacuum. H33- Dynamic Beam Profile Measurements at DESY using Synchrotron x-Radiation . W. EBELING, G. W. BENNETT,* Deutsche s Elektronen -Synchrotron - An instrument is des- cribed which images a section of the beam on a floures- cent screen using pin-hole optics and the short wave- length (< IDA.) part of the synchrotron radiation spectrum. The screen is viewed by a photomultiplier tube through a rotating-disk shutter. Radial and vertical beam profiles at various energies can be measured, on-line, with a resolution of 0.1 mm. *0n leave from Brookhaven National Laboratory. H3I+. Detectors for CEA RF Monitors . B. ANDERSON, Cam - bridge Electron Accelerator - CEA uses rf detectors as intensity and displacement monitors 1 > s in different parts of the machine. Due to different requirements, several types of detectors have evolved. The various detectors have sensitivities up to -105 dbm, a linear dynamic range of 70 db, bandwidths of 10 MHz, and digital readouts. Some of the noise pickup problems and various advantages are discussed. 1 B. Anderson, CEAL-IO3O 2 B. Anderson, S. M. Matin Proc . 6th Nat. Accel. Conf. A152 (1967). H35- Beam Monitoring at the NBS Linac - Energy, Cur- rent, Position, Charge . JOHN L. PENKE, national Bureau of Standards - The beam monitoring systems at the NBS Linac are briefly reviewed. This includes a pulsed magnet for energy display with a 200 scanned-gate elec- tronic system. Shielding and electronics for use with ferrite loaded position and current monitors are dis- cussed, and the use of a fast, wide-range integrator with ferrite current pick-ups is outlined. H36. E valuation of High Stability Secondary Emission Monitors . THEODORE DEPARRY AND LAZARUS G. RATNER, ' Argonne National Laboratory - A description of a stable, remotely operated, high vacuum (10~° torr), low scatter- ing ( 6 = 0.2^6 mrad) secondary emission monitor (SEM) system developed at ANL is given. A block diagram and important details of the electronic control circuits are shown. Performance characteristics of the SEM system covering the dynamic range of from 10° to 10^3 protons/ burst are given. With activation foils as reference standards, the experimental results of the secondary yield vs high energy primary protons are presented for the kinetic energy range of the primary protons of h to 12.5 GeV/c. Experimental and expected theoretical re- sults are discussed. *Work performed under the auspices of the USAEC. H37> Picosecond Beam Monitors and Data Acquisition System . N. J. N0RRIS AND R. K. HANST, E. G. and G . - The 30-A, 5°~ps electron pulse generated by the EG&G/ AEC Linear Accelerator permits the measurement of scin- tillator response functions and the study of other sub- nanosecond phenomena. To take advantage of this capa- bility a system for fast pulse monitoring has been developed. Faraday cups and non-intercepting monitors are designed to measure the electron beam current, and are used in conjunction with a unique data acquisition system for fast pulse measurements. This system uses the fastest available sampling oscilloscopes, modified for remote operation of the sampling elements, thus eliminating the signal distortion of the coaxial cable between the experimental measurement point and the data recording area. The digitized output of the sampling oscilloscope is stored and repeatedly averaged to in- crease the signal-to-noise ratio, allowing the measure- ment of signals that are about 100 ps in duration and a few millivolts in amplitude. The digital information, recorded on either magnetic or paper tape, is compati- ble with computerized data reduction techniques. This data acquisition system may be used on any recurring fast pulse and offers a sensitivity -bandwidth improve- ment of about 10? over the best traveling wave oscillo- scopes. H38. Calibrating and Evaluating Induction Electrode Designs Using Cathode Ray Beams .* JAKES R. SIMANT0N, Argonne National Laboratory - During the design phase and prior to installation in the Zero Gradient Synchro- tron (ZGS) straight sections, beam induction electrode behavior was thoroughly investigated with several methods, including driven wire techniques, chopped Van de Graaff proton beams, and cathode ray guns. Results presented demonstrate that the latter method provides the most realistic and versatile means of simulating in-machine behavior. Subsequent operation in the ZGS has been com- mensurate with test behavior. The paper describes the apparatus and technique used to calibrate electrodes at realistic frequencies without dependence upon the accuracy of RF instruments. Frequency, transient, and position response measurements are presented. Electrode design and the inherent superiority of electron beams relative to wire techniques for design evaluation are discussed. •Work performed under the auspices of the USAEC. H39-t Beam Current Transformer with DC to 200-MHz Range . K. UNSER, CERJI, Geneva - The paper describes methods of extending bandwidth, signal-to-noise ratio, and dynamic range in beam current monitors using large aperture (1U0 to 180 mm) toroid transformers. Three systems have been built - all feature nanoseconds rise time - but differ in complexity and low frequency cut- off. A single transformer device is used in the CERN Proton Synchrotron Linac. Operation close to the upper frequency limit (rise time 2 ns) is purely passive. An operational amplifier back-up loop extends the lower frequency limit to below 1 kHz. A dual toroid system is used in the CERN PS to measure the number of circulating protons with high precision. Separate high and low frequency channels combined in an active feedback loop yield a 30-ns rise time, together with an effective L?R time constant in excess of k hours. A triple toroid assembly will be used in the precision monitor for the CERN Intersecting Storage Rings. A magnetic modulator is combined with an active ac system to provide full frequency coverage down to dc. H**0. A Pulse-Signal Viewing System for Accelerators .* DALE T. VAN BUREN AND HUGH C. PADDOCKS, Los Alamos Scien - tific Laboratory - The operation of an accelerator re- quires that signals from various points about the machine be available for viewing in the control room. For the larger accelerators, the cable runs may be several thou- sand feet long. For such applications, a system is being developed with a 10$ to 90$ rise time of 80 nsec, over- shoot of < 0.5 dB, and a droop of less than 0.5$ for a 1-msec pulse. The necessary pre-emphasis filters for each cable run are designed by a computer program. The computational procedure on which the program is based will be described. A method for integrating the viewing system with a computer-based data acquisition and control system to provide for automatic switching will be dis- cussed. *Work performed under the auspices of the USAEC. H'+l.t Cryopumping the Omnitron Ultra-Vacuum System . Using Heat Fipes and Metallic Conductors . N. PILIER0N AND R. W0LGAST, Lawrence Radiation laboratory - The Omni- tron is a synchrotron with a storage ring that will de- liver beams of light and/or heavy ions at different ener- gies and currents. Storage of heavy ions in a high-charge state for 25 ms requires that the vacuum be specified carefully. A conservatively crude figure of merit, 10 14 < N -£ni zf is used where: N = 3 x 10 7 turns around the accelerator, ni = the concentration of atoms of the i th atomic number Zi. Cryopumping cold fingers are in- serted in each gap between magnets for both the synchro- tron and the storage ring (190 pumping stations). Each finger is cooled at one end by a distribution ring and consists of an 80°K jacket around a U°K core. Several tests of one full-size pumping station comprising an alumina beam tube brazed to stainless steel are given with heat pipes and metallic heat conductors in the cold- finger design. This approach permits the finger tempera- ture to be raised almost independently of the distribu- tion temperature. The < 7 hour pump down to the OMNITRON figure of merit achieved, gives the pumpdown time for the whole machine. HU2. The Titanium Vacuum Chamber for the Zero Gradient Synchrotron .* WILLARD B. HANSON, t Arponne National Labora - tory - An all-metal, titanium alloy inner vacuum chamber has been built for the Zero Gradient Synchrotron (ZGS). This chamber has high radiation resistance, high mechani- cal strength and provides mountings for pole face windings. The upper and lower surfaces of the chamber consist of 0.012-in. titanium skins which span the 32-in. aperture along the 5U-ft length of the octant. These skins are reinforced with radial T-shaped ribs 3/8-in. high to withstand the design loading of 30 torr. The 20 miles of titainium ribs are diffusion bonded to the skins to provide high strength joints that cannot leak. Eddy current problems are minimized by using an alloy of high electrical resistivity. Pole face windings mounted in holes in the ribs will be used to correct for the effects of the residual eddy currents. Many of the new techni- ques that were developed for aerospace applications were used to produce and test this chamber. These techniques and the results of the tests will be discussed. *Work performed under the auspices of the USAEC. •Now on staff of the National Accelerator Laboratory. HU3 . Corrugated Bellows Vacuum Chamber for Fast - Cycling Synchrotrons .* R. T. AVERY AND G. A. TLDRICK, Lawrence Radiation Laboratory - Historically, vacuum chambers for fast -cycling synchrotrons have been a prob- lem, usually due to some combination of poor reliability, excessive outgassing, fragility, radiation damage, field distortion, and high cost. Our study indicates that cor- rugated metal bellows -type vacuum chambers of several meters length are an attractive alternative. Excellent vacuum characteristics are achieved at a fraction of the cost of ceramic chambers. Calculations indicate that the increased electrical resistance due to corrugating the walls reduces eddy currents such that heat dissipa- tion and field distortions are not likely to be serious problems . Adequate structural strength can be achieved within dimensions comparable to those of ceramic vacuum chambers. Existing synchrotrons may benefit by retro- fitting the described bellows-type chambers in place of existing chambers. *Work performed under auspices of USAEC. H 1 * 1 *-. Elliptical Vacuum Chamber Stresses and Deflec - tions .* R. T. AVERY AND G. A. TIDRICK, Lawrence Radiation Laboratory - Equations are derived for the bending mo- ments and stresses at all points in a uniform wall tubu- lar chamber of elliptical cross section subjected to uniform pressure loading. Equations are also derived for deflections at the major and minor axes. Graphs and tables are included to facilitate computations. This data can be used directly for analysis of elliptical vacuum chambers which are frequently used in synchro- trons and elsewhere. The method employed can be used for analysis of vacuum chambers with cross sections other than elliptical. *Work performed under auspices of USAEC. Hi+ 5. Tests of a Fail-Safe Vacuum Beam Line Using Acoustic Delay and a Fast Closing Valve .* R. C. WOLGAST, AND J. W. DAVIS, Lawrence Radiation Laboratory - The fail-safe line is equipped with a McClure switch pressure rise detector, a labyrinth acoustic delay section, and an eddy-current driven fast closing valve. The line is representative of an injection or target beam line for the Omnitron, and is needed to protect the ultra-high vacuum system against sudden rupture of the vacuum enve- lope and the associated contamination. The valve closes a 1-in. dia. bore in less than 1 ms with 500 J in the power supply capacitors. The acoustic delay section (2 ft. long) delays the pressure rise by k ms. In simu- lated vacuum failures 11 ft. from the valve, without the delay section, less than 10~5 torr-liters of air (the sensitivity limit of the instrumentation) passed through the valve. The addition of an in-line liquid nitrogen trap and a residual gas 'analyzer will permit examination of the protected system for contamination. *Work performed under auspices of USAEC. ROUND TABLE DISCUSSION II. Round Table Discussion of Synchrotron Booster Injectors. E. D. COURANT, National Accelerator Laboratory; J. L. KIRCHGESSNER, Princeton -Pennsylvania Accelerator; J. M. PETERSON, Lawrence Radiation Laboratory ; K. H. REICH, CERM. Geneva. Switzerland. Moderator: R. BILLINGE, National Accelerator Laboratory. 12. The Design of the HAL Booster . R. BILLINGE, S.C. SNOWDON, A. van STEEHBERGEN, National Accelerator labora - tory - The design of the 10-BeV injector synchrotron for the KAL 200-BeV machine includes many interesting features. These have developed over a period of about one year, dur- ing which time many alternative approaches were considered. The magnets were designed using analytical computations to design pole contours whose effectiveness was subsequently determined both by finite permeability computations and field measurements . The concept of modular construction of the synchrotron ring as utilized at the Cornell 10-BeV machine has been incorporated in the definitive design. 13. t Beam Dynamics Problems in a Kultiparticle Rapid Cycling Synchrotron .* FRANK B. SELPH, Lavrence Radiation Laboratory - The proposed Omnitron facility includes a synchrotron that will accelerate protons to l.k GeV and heavier elements to tens of MeV per nucleon. To obtain intense high energy beams of the heavier elements, after the first acceleration cycle the beam is placed in a storage ring, then on the next cycle is stripped, rein- jected, and accelerated to hundreds of MeV per nucleon. As the particle species delivered by the injector is changed a range of e/m values from O.O5 to 1 must be accepted, and the intensity can change by orders of mag- nitude. Problems that arise in injection, bunching, acceleration, extraction, and reinject ion are discussed. Provisions for beam handling and control must be flexible enough to allow maximum possible exploitation of the accelerator facility. Possibilities for time-shared utilization of the machine are considered. For this to be most effective, each experimenter must be able to specify particle species and energy independently. It is also necessary to make a rapid changeover from one set of operating conditions to another. This sets require- ments for reproducibility, for rapid tuning, and for fast troubleshooting. *Work performed under auspices of USAEC. I 1 *- Progress on the German Proton -Synchrotron . F. ARENDT, J. ERB, W. HEINZ, K.-P. JUNGST, W. RUDLOFF, U. SIEGMUND, L. STEINBOCK, Kernforschungszentrum Karls - ruhe - Last year the Karlsruhe group proposed a proton synchrotron of ^0 GeV and 10 12 p/s in the extracted beam. The design has been reconsidered both with respect to lattice (separated function), and injection scheme. For about 20$ of the total capital cost of the machine it is possible to increase the intensity to 1013 p/p a t 1+0 GeV, or to keep the 10 12 p/s and increase the energy to about 60 GeV, or to install both these options. As a new ver- sion the last of these alternatives is proposed. Para- meters of this improved machine are given; the different stages of approach are discussed. 15. t Design of a 600-MeV Superconducting Microtron . D. C. SUTTON, A. 0. HANSON, D. JAMNIK, C. S. ROBINSON, AND P. AXEL, University of Illinois - The design of a 600-MeV racetrack microtron proposed for the University of Illinois will be discussed. It consists of a 30-MeV superconducting linac operating at 1.3 GHz between two uniform field bending magnets about 7 meters apart. There will be 19 parallel return paths separated by lU .7 cm. Vertical focusing is provided on each return orbit by a quadrupole pair close to each magnet. For quadrupoles 20 cm long and separated by 10 cm, the gradi- ents required to advance the vertical oscillation phase by 90° per revolution increase monotonically from 0.1 to 0.5 kilogauss per centimeter. Only very weak hori- zontal focusing powers are needed to keep the return beams within 2 mm of linac axis. The linac itself pro- vides some focusing but two weak quadrupole singlets on the linac axis, one near each magnet, provide additional focusing. A number of tests with single superconducting lead and niobium cavities are continuing in order to find a satisfactory method of fabricating and operating a superconducting accelerating section. 1°. Strong Focusing Race Track "icrotron . J. AUC0U- TURIER AND H. LEB0UTET, CSF - Corbeville - Whether the accelerator section used in the race track microtron is superconducting or not, focusing of the beam to avoid ar.y interception is a fundamental requirement. Furthermore since this kind of machine is likely to be able to devel- op very large average powers, some care in the adjustment of the beam is required. To achieve that, it is neces- sary that each orbit should be stable for betatron oscil- lations (excluding eventually resonances). One way of achieving that is to go to a triangular geometry (3 sym- metry) . It is then shown that this geometry permits a good orbit separation, separate orbit control, and ease of outgassing the accelerator waveguide, even of bigger dimension to allow operation at U50 KHz. 17. Some Construction Details for FFAG-Superconductinp; Accelerators . P. GERALD KBUGER AND J. II. SNYDER, University of Illinois - Frevious calculations 1 on superconducting FFAG accelerators have been refined and extended so that detailed Nb 3 -Sn coil configuration can be described. These are given for a 1-GeV model accelerator. The same general principles are extended for use in calculating fields from Nb 3 -Sn coil configurations for an FFAG accel- erator in the energy range of 2000 to 3000 GeV. Relative cost estimates for an FFAG versus pulsed accelerators will be given for some critical components of supercon- ducting and/or cryogenic accelerators. Advantages and disadvantages of pulsed versus FFAG accelerators will be discussed. 1 P. Gerald Kruger and J.N. Snyder, "Calculations Concern- ing Superconducting Accelerators", Proceedings of the Brookhaven Summer Study on Superconducting Devices and Accelerators: 1968. To be published about Dec. 1968. 18 • Performance of the Superconducting Injector for the Stanford Linear Accelerator . E. JONES AND L. SUELZLE, Stanford University - This report describes some recent ex- periments performed with a prototype of the injector sec- tion eventually to be used in conjunction with the super- conducting linear accelerator at Stanford University. I9-t Feasibility Study of a Two-Kile Superconducti ng Linac * W. 3. HERRMALIISFELDT, G. A. L0EW, AND R. B. NEAL, Stanford Linear Accelerator Center - Assuming that inves- tigations now underway will result in superconducting accelerator structures capable of withstanding gradients of 10 MeV/foot, a feasibility study of a two-mile 100-GeV superconducting electron linac with 6% duty cycle has been made at frequencies of 1U28 and 2856 MHz. Tentative machine parameters and the preliminary design of compo- nents and systems are examined. These studies are based upon a traveling-wave accelerator structure with rf feedback in each U0-ft. section. ♦Work supported by the USAEC. 110. RF Superconducting Materials Research at SLAC * M. A. ALLEN, N. DEAN, Z. D. FARKAS, E. L. GARWIN, H. A. HOGG, E. W. HOYT, R. A. McCONNELL, M. RABINOWITZ, AND A. RODER, Stanford Linear Accelerator Center - Pro- gress of the materials research program is described. The program objectives are to evaluate materials and develop processing and fabrication techniques which it will be economically feasible to use in the construe - of a high-gradient (10 MeV/foot) two-mile linear accelera- tor. RF properties are evaluated by cavity Q measure- ments at selected frequencies in the range 3 to 11 GHz. Techniques for reducing field emission are being sought. At present, this phenomenon is being studied by making dc measurements at room temperature. RF superconducting properties are known to be very sensitive functions of material purity and crystal structure. For this reason, various methods of deposition, surface purification, and heat traatment are being tried. Most work is being done with lead and niobium, but technetium plating is being actively investigated. *Work supported by the USAEC. HI. Investigation of Superconducting Niobium Cavities at S-Band .* H. HAHN AND H. J. HALAMA, Brookhaven National Laboratory - Pure lead, niobium, and technitium are the elemental materials which exhibit properties suitable for superconducting rf devices such as linear accelerators or rf beam separators. Considerable experimental information is presently available for lead, whereas relevant results for niobium were obtained at X-band frequencies only. .This paper describes our investigation of superconducting Nb cavities at S-band frequencies (2.87 GHz). The TEoil and TMoil cavities were machined by Varian Associates from solid billets of electron-beam-melted niobium and then chemically polished to remove all work-damaged material. We found that the intrinsic quality factor of Nb cavities is at equal temperature about l.k X Q of Pb. The niobium TE n cavity has a Q (^.2°K) ~ 325 x 10s and a residual Q re s kTxIO 9 , whereas the TMqh cavity has a Q (U.2°K) « 89 x 1C6 and a residual Q res *= 392 x 10 s . Power measurements in the TMoil cavity were limited by multipactoring. More detailed studies are in progress and will be presented in the paper. *Work performed under the auspices of the USAEC. 112. Measurements of the RF -Absorption of Supercon - ducting Resonators . P. FLBCHER, J. HALBRITTER, R. HITSCHOLD, P. KNEISEL, W. KUHN, L. LIST, 0. STOLTZ, L. SZESCI, Universitat Karlsruhe - The measured surface resistance R of superconductors deviates remarkably from theoretical prediction of the BCS-theory R-gcs a ^ l° w temperatures and high field levels. At low temperatures the residual surface resistance Rr ss is large compared with the surface resistance in the frame of the BCS- theory. The reason for this is not well understood at present. Therefore, measurements are performed on the dependence of RRes on frequency and on electric or mag- netic field amplitude. At higher temperatures and low rf -field amplitudes the measured and calculated surface resistance agrees. At high field levels however the measurements indicate deviations from the BCS-theory, especially if there is a rf -electric field perpendicular to the surface. To clarify these deviations experiments were undertaken. The dependence of the absorption on the shape and on the depositions (galvanizing or evapori- zing) is also studied. 113. Measurement of Beam Loading Effects in a Super - conducting Structure . M. KUNTZE, K. MITTAG, K. PACK, G. WINKLER, J. VETTER, Universitat Karlsruhe - In an electron experiment the properties of a superconducting structure for a proton linear accelerator at 760 Mc were studied. The experimental setup offers the possibility to investigate beam loading effects, which are expected to severally effect the dynamical behaviour of a super- conducting proton linear accelerator. Simultaneously, the electron experiment delivers several independent methods of determining the superconducting shunt impe- dance. First results of beam-cavity interactions at He -temperature were obtained in a one-meter accelerator model. Narrow electron bunches are decelerated in the self -induced fields with no rf -power fed to the super- conducting structure. . A rf -power proportional to the square of the chopped current was measured outside the cavity. From these measurements a value for the shunt impedance can be deduced that is in agreement with the Z-value obtained from continuous beam measurements. With rf -power fed to the structure, measurements under heavy beam loading are going on and the excitation of higher modes is studied. II 1 *. Transient Beam Loading in Electron Linear Accel- erators .* J.E. LEISS, S. PENNER, J.E. ROSE AND J.B. BRO- BERG, National Bureau of Standards - Most theories of the transient behavior of linear electron accelerators do not include dispersive effects or the additional beam loading due to excitation of various space harmonics in the wave- guide. Attempts to include dispersive effects in calcul- ations 1 ' 2 ' 3 have yielded conflicting predictions. There is great interest in this subject because of the implica- tions to very high energy electron ring accelerators. 4 An experiment to measure these effects has been devised by sending a well analyzed and bunched electron beam through either an unexcited accelerator waveguide or a vacuum pipe. Electron energy loss due to beam loading in the waveguide is detected by measuring the shift in energy of elastically scattered electrons with the NBS electron scattering spectrometer. Energy shifts of a few parts in 10 s can be measured. Preliminary measure- ments at 60 MeV and for beam pulse lengths of 5 5 10, and 20 ns appear to be in agreement with references 1 and 2 when both dispersive effects and space-harmonic excita- tion are included. For 5-ns rectangular beam pulses a sixteen-fold increase in beam loading is predicted over calculations that do not include these effects. Since the energy shifts observed are small, we are searching for possible systematic errors in the experiment. We plan to extend the measurements to shorter electron beam pulses and to different electron energies. 1 J.E. Leiss and R.A. Schrack, NBS Internal Report 166 (Oct. 30, 1962). 3 J.E. Leiss, IEEE Trans, on Nucl. Sci., NS-12, 566 (1965). 3 B. Epszstein and J. P. Magnin, Prdc . of the Los Alamos Linac Conf., IA-3609, 332 (1966). 4 J.D. Lawson, Rutherford High Energy Laboratory Report RHEL/fflM , (April, 1968). *Work supported by USAEC, Division of Research. H5 • Excitation of a Closed Cylindrical Cavity by a Charged Object Moving along the Axis at Constant Velocity .* B. S. LEVINE and A. M. SESSLER, Lawrence Radiation Labora - tory - An important aspect of the design of high-current devices is the beam loading of the accelerating structure. The phenomenon is sensitive to the charge distribution of the beam and to the geometry of the structure . Calcula- tions for realistic geometry are difficult; to gain in- sight, a number of authors have studied the simplified problem of beam interaction with a closed, right cylin- drical cavity. 1 ' 3 ' 3 A formal solution, for arbitrary charge distribution, has been given as a (double) sum over the modes of the cavity. 2 It has been emphasized by all previous workers that the simplified problem approxi- mates reality only for those modes having wavelengths large compared to the holes in an actual structure. We have developed a computational program which evaluates the formal expression for cavity excitation. Sums over selected sets (or all) modes are available. A cylindri- cal beam pulse is characterized by its length and inner and outer radii. Parametric studies will be presented of the total cavity excitation by a charged ring. *Work supported by the U. S. Atomic Energy Commission. 1 0. A. Kolpakov and V. I. Kotov, Sov. Phys . - Tech. Phys. 9, 1072 (1965). 2 K. B. Winterbon, AECL Report FSD/lNG - 16 (1965). 3 P. L. Morton and V. K. Neil, LRL Report UCRL-18103 (1968). Il6.t A Method for Static-Field Compression in an Electron -Ring Accelerator .* L.J. LASLETT AND A.M. SESS- LER, Lawrence Radiation Laboratory - In the original pro- posal of Veksler et al., 1 the electron ring of an electron- ring accelerator (ERA) is compressed by a pulsed field from a large to a small radius and with an associated in- crease of electron energy. As Christofilos has noted, 2 compression can be achieved (without an energy gain) in a static magnetic field. With acceleration divorced from the compression function, the need for large supplies of pulsed power is avoided, and increased repetition rates become possible-- at the expense of a higher-energy in- jector. In contrast to the method of Ref. 2, static -field compression can be achieved without the use of alternat- ing sections of axial acceleration and deceleration. A means for static-field compression without axial accelera- tion is described, and examples are given of the field configurations and coil arrangements that are required. It is proposed that axial focusing can be maintained with this arrangement through the provision of a small travel- ing magnetic well that serves to convey the ring through the compressor. ♦Supported by the USAEC. 1 V. I. Veksler et al., Proc . VI International Conference on High Energy Accelerators , Cambridge 19=7, P- 289. 2 N. C. Christofilos, LRL Report UCID-15378 (19S8). 117. t Collective-Ion Acceleration at Very High Energy in a Static Magnetic Field .* lilCKOLAS C. CHRIsrOFILOS, Lawrence Radiation Laboratory, Livernore - Extremely relativistic electrons injected in a static magnetic field form a ring that can subsequently be compressed by a sequence of axial acceleration and deceleration, as previously reported. Ions trapped in the electro- static field of the electron ring can in principle be accelerated in a decreasing magnetic field to very high energy (yi) where Yj < Y e and lj, Y e are the final ion and electron energy, respectively, expressed in rest mass units. The electrons in the ring are confined by an external magnetic field. Radial stability of the trapped ions is provided by imposing an azimuthal momen- tum on the ions equal and opposite to the electron azi- muthal momentum so that both ions and electrons are mag- netically focused by the external magnetic field. The ions are initially accelerated by adiabatic expansion of the ring in a decreasing magnetic field; subsequently the ring is decelerated at constant radius. During this step the ions acquire an azimuthal mechanical momentum almost equal to that of the relativistic electrons. The azimuthal momentum of the ions and electrons are subse- quently equalized by allowing the electrons to lose energy by synchrotron radiation. Preliminary parameters of a static magnetic field 1000-GeV ion accelerator are presented. ♦Work performed under the auspices of the USAEC. H8- Theoretical Studies on the Formation and Expansion of a 23-MeV Electron Ring in a Solenoidal Magnetic Fie ld. R. BERG, H. KIM, D. NELSON AND M. REISER, University of Maryland - In the proposed electron-ring accelerator schemes that are presently under study 1 the ring is formed by injecting a U.5-MeV electron beam into a solenoidal field and subsequently compressing it adiabatically to the desired diameter of about 7 cm and an energy of about 23 MeV. After being loaded with positive ions the ring is either injected into a linear accelerator or ion ac- celeration is accomplished by simple expansion in the magnetic fringe field. We have investigated the expan- sion process with a computer program called HELIX which integrates the relativistic equations of motion in three dimensions. Magnetic field data can be used in either analytical form or as an array of data points . The effects of initial conditions (energy spread, width and divergence) on the beam structure during expansion have been studied and are compared with the adiabatic theory. The possibility of forming an electron ring by nonadia- batic axial injection of a 23-MeV beam into a solenoidal field was also investigated. 1 Symposium on Electron Ring Accelerators, Report UCRL-18103, Feb. 1968. 119. Flat -Topping Magnet Current for the Berkeley Electron Ring Accelerator Experiment .* WILLIAM R. BAKER, WILLIAM L. GAGMON, AND FERDINAND VOELKER, Lavrence Radia - tion Laboratory - The Berkeley electron ring accelerator experiment requires that several time -sequenced magnetic fields be generated to compress the injected electron ring from a radius of 25 cm to a radius of 3-8 cm. It is necessary to hold the electron ring at 3-8 cm radius for several milliseconds to study radiation and gas ioniza- tion effects in the compressed ring. This is done by flat-topping the current in a short -time-constant magnet to within 3$ for 3.0 msec. The magnet current is pulsed to an initial value of 27,000 A by a capacitor bank and series ignitron switch. A solid-state diode clamps the current at this value; the current then begins to decay at a rate determined by circuit losses. The "flat -top" circuit adds enough energy to compensate for the average I R losses. This is accomplished by sequentially dis- charging capacitors into a transformer, the secondary of which is connected to the 30,000-ampere magnet circuit through a solid-state diode bridge. Simple design equa- tions are developed which are applicable for flat-topping similar magnets. Also discussed are some of the critical aspects of the design. *Work supported by the USAEC. 120. t Mechanical Design of Coir.pressor Test Apparatus for "Electron Ring Accelerator" Research .* R. T. AVERY, H. P. HERNANDEZ, R. M. REIMERS, W. W. SALSIG, Lawrence Radiation Laboratory - The concept of accelerating a dynamically stable fraction of heavy ions in a fast- turning ring of electrons opens a new dimension for par- ticle accelerator design. Apparatus to investigate in- jection, compression, and ion loading of very high current electron rings has been constructed and operated at LRL. This paper will present design and hardware features of the apparatus. The intense beam of electrons is obtained from Project Sherwood's "Astron." The beam channel to the ERA compressor must select the brightest fraction, pass only a few nanoseconds of the 250-ns U00-A "Astron" pulse, and provide a transition from ordinary to ultra high vacuum. Sequential excitation of three coil pairs creates a magnetic mirror bottle in the com- pressor. The magnetic field at the electron ring rises from near zero to 20 kG in about 700/zs. Because of this rapidly changing field a ceramic vacuum chamber is used, and an epoxy-fiberglass laminate structure resists the 5-ton dynamic load from the coils. Design studies of a comtemplated apparatus to investigate ion loaded electron rings during extraction from the magnetic bottle and sub- sequent magnetic acceleration will also be discussed. *Work performed under auspices of USAEC. 121 . Measurement and Optimization of the Emittance of a 300-nsec, 250-A, 3-U-MeV Electron Beam .* R. W. ALLISON. JR., J. W. BEAL, W. L. EVERETTE, J. R. GUGGEM0S, W. A. S. LAMB, R. M. RICHTER, W. A. SHERWOOD, R. L. SP0ERLEIN, J. TANABE, R. E. WRIGHT, AND E. ZAJEC, Lawrence Radiation Laboratory - The two-dimensional emittance of the 3. 1 *- MeV, 250-A electron beam produced by the Astron linear induction accelerator has been measured. The measurement utilized a slit plate and a glass slide. A densitometer scan of the slit pattern formed on the glass by irradi- ation was analyzed and emittance contours drawn. Substi- tution of a radiation-resistant Mn-activated AI2O3 scin- tillator permitted observation of the slit pattern of each pulse by using television. This equipment allowed the induction accelerator to be tuned for minimum emit- tance without excessive beam loss. Ninety percent of the beam was within a phase -plane area of 0.17 cm-radians. Data on the two-dimensional phase -space density are also presented. *Work sponsored by the USAEC. 122 . Fast Beam Choppers for the Electron Ring Accel - erator .* ANDRIS FALTENS AND CORDON KERNS, Lawrence Radi- ation Laboratory - Two beam choppers were constructed which produce a 20-ns nearly square pulse of 3 + MeV electrons out of the best portion of the 300-ns Astron beam, or an 8-jis microwave electron linac beam for injec- tion into the ERA compressor. The choppers are imped- ance matched traveling-wave devices that deflect the beam with equal strength electric and magnetic forces , and are powered with either 3 electrode spark gaps or thyratrons and a 20-ns pulse line. The electron beam is biased out of the beam transport system with a dc magnetic field and pulsed into it with the chopper. *Work supported by the USAEC. 123- 1 The Fixed-Field, Rotating-Magnet Synchrotron or: Why Pulse? M. L. GOOD, State University of New York at Stony Brook - A scheme is presented whereby dc supercon- ducting magnets may be used to make up an ultra-high energy AGS. The necessary time variation of guide and focusing fields is achieved by slowly rotating dipole and quadrupole elements about the beam axis . The plan is not impractical in any obvious way. Power require- ments are those of the rf, plus Dewar losses; no ring magnet power supply is needed. I2U. A Polarized Photon Beam for the SLAC 82-Inch Hydrogen Bubble Chamber .* CHARLES K. SINCLAIR, Tufts University ; JOSEPH J. MURRAY AND PAUL R. KLEIN, Stanford Linear Accelerator Center ; MONROE RABIN, Lawrence Radi- ation Laboratory - A highly polarized beam of high energy photons has been produced at the Stanford Linear Accel- erator by Compton back-scattering ruby laser quanta from a high energy electron beam. Photon energies from l.k to 5-9 GeV are obtained by varying the electron energy from 8 to 18 GeV. Intensities are more than adequate for bubble chamber exposures. Monochromatization to a few percent, dependent on the peak photon energy, is achieved by limiting the electron beam phase space and collimating the scattered photon beam. Average polari- zation, also dependent on the peak photon energy, exceeds 90$. Any state of circular or linear polarization is selectable on a programmed pulse-to-pulse basis. The only backgrounds, from synchrotron radiation and residual gas bremsstrahlung, are completely eliminated by a com- bination of soft magnetic fields, collimation, a thin uranium absorber (0.01 X ), and high vacua as required. Details of the beam design, and measurements of its characteristics are presented, along with techniques for further improvement in energy, intensity, and resolution. *Work supported by the USAEC. 125. A Laser Induced Compton Back-Scattered Photon Beam at the Cambridge Electron Accelerator . JON R. SAUER, RICHARD H. MILBURN, AND CHARLES K. SINCLAIR, Tufts Uni - versity ; MIRCEA F0TIN0, Cambridge Electron Accelerator - At the CEA, a 20 joule per pulse normal mode ruby laser is being used in an attempt to produce a highly polar- ized hard photon beam of intensity suitable for high ener- gy physics experiments. The measured energy spectrum of these Compton back-scattered photons and the yield of about U0 quanta per laser joule per mA of accelerated electron beam are in reasonable accord with theoretical expectations. We have further demonstrated that Compton scattering of a laser beam is a suitable non-destructive probe of extreme relativistic charged particle beams by measuring the spatial' density of the CEA internal beam in the horizontal plane, as well as its variation with machine energy, orbit perturbations, and time during the acceleration cycle. It appears possible to determine the parameters of the beam phase-space ellipses, making a complete description of ultra-relativistic beams accessible to the laser beam probe technique. Attention is called to the possible application of this technique to storage ring beams, particularly in the crossing regions where other methods of beam monitoring are diffi- cult . INVITED PAPER jl. Electron Positron Storage Rings: Status and Present Limitations . FERNANDO AMMAN, CNEN-Frascati - The current status of electron and positron storage rings is reviewed. The experimental results on beam instabilities, their con- sequences on the design of a high current storage ring, and the technological problems involved are discussed. INVITED PAPER J2. Superconducting Synchrotrons .* MICHAEL A. GREEN, Lawrence Radiation Laboratory - Superconductivity has advanced considerably since the discovery of high field type II superconductors in .1961 . During the last two years supercon- ductivity has at last become a tool of high energy physics. One may now consider the construction of a superconducting proton synchrotron. Several laboratories in the United States and Europe are studying the feasibility of superconducting synchrotrons. A realistic look at such a synchrotron requires a study of the machine components and their interaction, and a study of the fundamental properties of such a machine. Economics will be the prominent reason for ultimately building such a machine. Since the magnet system is the primary difference between superconducting and conventional machines, it is emphasized. There is a short discussion of magnet coil configurations, superconducting materials, and the use of iron as a magnetic shield and return path. The magnet system also consists of a power supply, cryostats, and a refrigeration system. All of the components are discussed in some detail. The use of superconducting synchrotron magnets permits one to consider a number of alternative solutions to rf, vacuum, and injection-extraction problems. Changes in the enclosure and other conventional facilities for a superconducting machine are discussed. A rough cost est- imate of superconducting synchrotrons is presented. The effect of field, beam intensity, and repetition rate on cost is discussed. In conclusion, it is shown that a superconducting synchrotron is both feasible and economical. *Work performed under the auspices of the USAEC. INVITED PAPER J3. Structures for Superconducting Electron Linacs and RF Separators . P. B. WILSON,* CERN , Geneva - The problems involved in the design of suitable structures for superconducting electron linacs or for superconducting rf separators are similar in many ways. In this paper some basic principles are developed which apply to the design of structures for both devices. In optimizing superconducting structures, the emphasis is different than for conventional structures. The gradient in a superconducting structure is limited by effects depending on the peak electric and magnetic fields at the superconducting surface. It is of primary importance, therefore, to reduce these peak fields as much as possi- ble relative to the average gradient, even if some shunt impedance must be sacrificed. The designs of various standing- wave structures, such as ir-mode and bi-periodic structures, are considered from this point of view. However, the struc- ture that gives the highest gradient for a given peak field is the traveling-wave resonator. This type of resonator is treated in some detail, since its behavior is less familiar and somewhat more complex than is the case of standing-wave resonators. In particular, the matching of such a resonator must be accomplished with great precision or substantial power will flow in the reverse direction. Other factors that enter into the design of superconducting structures, such as tuning, coupling, and thermal and mechanical stability, are also considered. *0n leave from Stanford University. INVITED PAPER J 1 *. The Stanford Superconducting Linear Accelerator Project . W.M. FAIRBANKS AND H.A. SCHWETTMAN, Stanford University - A progress report is given on the development of a 500-ft superconducting linear accelerator and the associated low temperature facility. INVITED PAPER J5> Refrigeration for Superconducting and Cryogenic Systems . T.R. STROBRIDGE AND D.B. CHELTON, National Bureau of Standards - Cryogenics and high energy physics have been intimately associated for many years. The liquid hydrogen bubble chamber remains a primary detector for particle interactions, and the recent successful development of super- conducting rf cavities will vastly improve the duty cycle of linear accelerators. Aside from target and detection devices , it is not clear what role low temperature environments will play in the particle accelerators now being con- ceived. The amount of cooling required and the refrigeration temperatures may vary widely from concept to concept. To assist in planning, this survey of modern cryogenic refrigerators, covering refrigeration temperatures from about 1.8 K to 80 K, gathers together performance, physical characteristic, and typical cost information from industry, academic, and government sources both in the U.S. and abroad. Whenever possible, data on liquefiers are converted to an equivalent refrigeration capacity. The capacities discussed range from about one watt to kilowatts. The last minute status of the newest low temperature facilities is summarized. INVITED PAPER j6. Accelerator Power Systems .* G. K. GREEN, Brookhaven National Laboratory - Accelerator facilities use large amounts of power and convert most of this power to frequencies and voltages quite different from those of the incoming lines. High energy facilities now tend to require much more power for their experimental programs than they do for the accelerator proper. Power conversion is being influenced by the development of solid state devices. One can begin to anticipate radically different approaches to solid state conversion and to control with digital techniques. It is also probable that the power characteristics of experimental areas will undergo drastic revision as cryogenic magnets are introduced for beam transport and spectrometers . •Work performed under the auspices of the USAEC. AUTHOR INDEX Abdelaziz, M. E., D19 Allen, M. A., 110 Allison, P. W., B29 Allison, R. W., Jr., 121 Amman, F., Jl Anderson, B., H3^ Andrews, R., C26 Arendt, F., Ik Armstrong, A.G.A.M., C2T Aucouturier, J., D5, l6 Averill, R. J., B33, G10 Avery, R. T., H^3, Kkk, 120 Awschalom, M., F26, F31 Axel, P., 15 Azam, G.j D3, T>k, D5 Baker, C. P., E21 Baker, W. R., 119 Bardin, B. M., El Barsotti, E. J., G7 Barton, M. Q., C21, HI Beal, J. W., D2, 121 Bell, R., F35 Benaroya, R., E2^ Benjamin, J. A., B21 Bennett, G. W., C21, F37, H5, H33 Bennett, R. L., H28 Bensussan, A., D^ Benton, A. C13 Berg, R. E., E9, E10, Il8 Berndt, M. M., G12 Bertuccio, T., B31, F6 Biggs, J., G19 Billinge, R., II, 12 Bittel, F., E23 Blewett, J. P., G15 Blosser, H. G., E2 Blumberg, L. N., C21 Boehne, D., D26, D28 Booth, R., F2T Brescia, A., H20 Bres, M., D2^ Bridges, J. F., E9 Britton, R. B., G15 Broberg, J. B., 11^ Browman, A., C25 Bruinsma, P. J. T., D6, DT Buchanan, V. J., F7 Budge, E. C, H24, H29 Burba, K., G3*+ Burger, R., El? Caling, N. J., BIT Carpender, W.. P., F^3 Carneiro, A., E1T Cassel, R. L., G3 Cassidy, T. D., F38 Chabert, A., B2k Chamberlain, W., Gl6 Chang, C. T. M., F^ Chapman, W. S., ClU Chasman, R., CIO, C17, D15 Che It on, D. B., J5 Chidley, B. G., C12 Chien, C. S., C8, ttk Chmara, F., B19 Christofilos, N. C, 117 Chuck, E., D23 Clark, D. J., B30, El6, E17 Claus, J., Cl6 Clay, H., F35 Cleland, M. R., Bl6, B2U, B27 Cohen, R., E5, E6, E8 Collins, T. L., A3, B33 Concaildi, G., H10 Cornish, G. W., H7 Courant, E. D., C2, II Craddock, M. K., E3 Crebbin, K. C, H12 Dahl, P. F., G15 Daugherty, J. D., B8, B9 Davie s -White, W., F^O Davis, J. W., H26, H^+5 Dawson, J. W., FU, F5 De Vries, C, D6, D7 Dean, N., 110 Delphin, P., E9, Ell, E12 DeLuca, W. H., H2 DeParry, T., H36 DeVito, B., D21 Dexter, W. L., H26, H27 Dickinson, T., G23 Dinkel, J. A., Fl Dmitrievsky, V. P., Ek Dobson, J., C19, C32 Dupont, F., E9, E12 Dupuis, A., E9 Dzubay, T. G., F22 Gunderson, G., HU Ebeling, W., H33 Elioff, T., B39 Ellefsplass, M., F25 Elo, D., B30, E1T Emigh, C. R., B7, B29 Eninger, J. E., B8, B9 Eno, E., F^3 Erb, J., Lk Etter, J., H19 Evans , D., HIT Everette, W. L., 121 Eyber, H., E23 Fairbanks, W. M.j J^ Faltens, A., 122 Farkas, Z. D., 110 Faulkner, J. R., D20 Fauska, H., BIT Flatau, C R., F2*+ Flecher, P., 112 Force, R. J., B39 Forster, G. A., F27 Foster, C. C., F32, F33 Fotino, M., 125 Fox, J. A., GU Fox, J. D., C21, H5 Frankel, R., H6 Franken, A. J. J., El4, E15 Frazier, P., B30, E17 Funsten, H. 0., E27 Gagnon, W. L., Fll, 119 Galejs, A., C20 Gallagher, W. J., C15, C19, D12, G30 Garren, A. A., C29 Garvin, E. L., 110 Gavet, J-C., D2U Geel, J., E15 George, R., HU, H10 Gilbert, F. S., Gil Gilbert, W. S., GlU Gluckstern, R. L., C9, D15, Dl6 Good, M. L., 123 Gore, R. A., H22 Gorka, A. J., F38 Greeley, F., H25 Green, G. K., j6 Green, M. A., J2 Greenebaum, B., F32 Grobner, 0., H13 Guggemos, J. R., 121 Haberl, A. W., B3U Ilahn, H., Ill Haken, J., F21 Halama, H. J., Ill Halbach, K., G22 Halbritter, J., 112 Hall, W. C., Fl8 Hammersand, F. G., D10 Hand, L. N., C25 Hanley, P. R., B5, Bl6, B2U, B3^+ Hanson, W. B., H42 Hanson, A. 0., 15 Hanst, R. K., D13, H37 Harold, M. R., C28 Harris, C. A., G38 Hart sough, W. D., B39 Harvey, A., F28 Haughian, J. M., D23, D29 Hauptman , J . M . , G20 Hay, R. D., G2^ Hazewindus, N., E13, ElU Heinz, W. , lk Heller, F., Cll Helm, R. H., D8 Henderson, T., D23 Hendry, G. 0., E25 Henness, J., Hl^ Hereward, H. G., C^ Hernandez, H. P., Ylk, 120 Herrera, J. C, C7 Herrmanns feldt, W. B., 19 Hessinger, J., E21 Hirschmann, H., Cll Hischold, R., 112 Hoenig, M. 0-, F3k Hoffert, W. J., D22 Hoffman, E. W., Hl8 Hogg, H. A., D8, 110 Homsy, G., F^2 Home, R. A., F25 Hornstra, F., Jr., B38, H3 Horrigan, E. W., F20 Hortig, G., B3, B13, BlU Howell, L. N., E19 Howe, F. A., Bl8 Hoyer, E. H., G22 Hoyt, E. W., 110 Hsieh, H. C H., C21, G27 Huber, H., C31 Hudson, E. D., E19 Isaila, M., B31, F6, H14 Jablonski, E., F7 Jameson, R. A., D22 Jamnik, D,, 15 Janes, G. S., B8, B9 Jaouen, J. , G28 Jean, R., E9 Jenkins , K. D., E9, H19 Johnson, C. D., H31 Johnson, J. W., B4 Johnson, W. P., E22 Johnson, D. L., Bll Johnson, T. H., E9 Jones, W. J., F42 Jones, E., 18 Jungst, K.-P., 14 Katz, J. E., F10 Keane, J. T., D18, D21 Keefe, D., A5 Kerns, C, 122 Kerns, Q. A., Fl, F10 Khoe, T. K., C18, E24 Kim, H., E9, G30, 118 Kim, H., Ell Kirchgessner, J. L., F6, II Klaisner, L. A., Fl Klein, P. R., 124 Knapp, E. A., D14 Kneisel, P., 112 Knott, M. J., H4, H20, H25 Koepke, K., H14 Kolomensky, A. A., C5 Komar, E. G. , Gl Koontz, R. F., D8 Kracht, U. , H8 Kruger, P. G. , 17 Kuhn, H., G21 Kuhn, W., 112 Kuntze, M., 113 Kustom, R. L., F4, F12 Lacaze, R., E9 Lamb, W. A. S., 121 Lancaster, J. H.. B40 Lankshear, R. F., D18 Lari, R. J., G2 Larsen, F., F6 Laslett, L. J., 116 Laubert, R., B28 Law, L. A., G25 Lebacqz, J. V., D9 Lebedev, A. N. , C5 Leboutet, H., C31, D3, D4, D5, E9, 16 Lee-Whiting, G. E., C12 Lee, M. J., C2, D15 Leiss, J. E., Dl, 114 Levine, G. S., F30, H5 Levine , B . S . , 115 Levy, R. H., B8, B9 Lewin, J. D., G13 Levis, L. G., H4, H25 Lewis, T. A., Bll List, L., 112 Litsinger, E. C, F43 Livingood, J. J., E24 Livingston, R. S., E19, G39 Loew, G. A., D8, 19 Lothrop, F. H., H12 Lou, K. H., B39, G20 Lucas, L. R., F29 Luccio, A., B30, E17 Lyster, M. K., F43 Machen, D. R., H16, H22 Maddocks, H. C, H40 Madsen, J. H. B., H16 Main, R. M. , D23, D29, G39 Mallory, M. L., E26 Mann, J., E21 Mann, J. E., KL9- Marcato, P., HIS Marcks, D. F., F39 Marcowitz, S., B38, H10 Markley, F. W., F27, G19 Mark, J., F35 Martin, E., E5, E8 Martin, J. A., E19, E26, G39 Martin, T. H., BIO, Bll Maschke, A., C26 Mason, C. F., B16 Maurer, W., C33 Mavrogenes, G., C18 McConnell, R. A., 110 - McCracken, R. J., E21 McKamey, A., G19 McNeil, W. R., B12 McNerney, A. J., D< McNerney, A. J., D21 Meads, P. F., Jr., C22, Menke, J. L., H35 Meuser, R. B., G17 Meyer, E. A., B7 Middelkoop, W. C, G21 Milburn, R. H., 125 Millar, R., F20 Miller, R. H., D8 F13 Milleron, N., H41 Minati, K. F., B22 Mints, A. L., B37 Mittag, K., 113 Mobley, R., C26 Month, M., C7 Moore, W. H., F30 Moretti, A., F5 Morgan, G. H., G15, G31 Morgan, R. H. C, C27 Morganstern, K. H., B16 Morris, D., B30, E17 Morris, D. I., D22 Morse, D. S., F21 Morton, P. L. , C4 Mosko, S. W., E19 Mueller, M., B3 Mueller, D. W., B7 Murray, J. J., 124 Naumov, A. A., A2 Nawrocky, R. J., C21, H5 Neal, R. B. , D8, 19 Neet, D. A. G., H13, H32 Nelson, D., G30, H19, 118 Netter, F., D3 Nordby, D. H., H18 Norris, N. J., D13, H37 O'Brien, K., F15 O'Connell, M. J., C27 O'Hanlon, H., G21 Ohnuma, S., E5, E8, E28 Ormrod, J. H., B6 Otte, R. A., B36 Pack, K., 113 Par slow, L. G., HI 8 Parzen, G. , G32 Passner, A., B31, F6 Passow, C, Cll Patterson, J. M., G25 Peerson, J. J., F5 Pelegrini, C., C2 Penner, S., 114 Pering, N., Dll Perraudin, C., D5 Petersen, G. W., C15 Peterson, H. K., D15 Peterson, J. M., II Phillips, E. A., F32 Pierce, W., F35 Pinel, J., G28 Pollock, R. E., F22 Pottier, J., D25 Potts, C. W., F39 Praeg, W. F., G6, G7 Prelec, K., F6 Prestwich, K. R., Bll Pruett, C. H., B36 Rabin, M. , 124 Rabinowitz, M. , 110 Rainwater, J., E5, E6, E7 Raka, E. C., C6 Rainier, W. J., E24 Ratner, L. G. , B38, H36 Rawkowsky, G., F9 Reagan, D., H15 Reay, N., B38 Rees, G., F3 Reginato, L. L., F8 Reich, K. H., II Reimers, R. M. , 120 Reinhold, G., B25, B26 Reiser, M., E9, Ell, E12, G30, 118 Renkas, M. , B30, E17 Repeta, L. E., H5 Resmini, F. G., E16, E17 Richardson, J. R., E3 Richardson, E. G., Jr., E19 Richter, R. M., 121 Richter, W., F25 Rickey, M. E., El Rieben, P., H13 Rind, E., F17 ill, rj., ri/ Robinson, D. M., Al Vinson, Co S. - T5 Robinson, R. K. Rob B28 mson, u. ivi., /u. inson, C. S., 15 Robinson, R. K., B2 Rode, C., C26 Roder, A., 110 Rohrraayer, A., G5, G8, G34, Rojers, E. J., B20 Roman, R. D., F36 Romanowski, T., B38 Rose, J. E., 114 Rose, P. H., G39 Roskowski, E., G35 Rouse, G., C25 Roux, G., D4 Rowe, E. M., B36 Rubchinsky, S. M., F2 Rudloff, W., 14 Ruedenaur, F. G., B2 Ryan, J. F., H9 Ryan, R. M., F21 G36 Ryding, G., B19 Sacherer, F. J., C3 Sagnell, B., H13 Salsig, W. W., G9, 120 Sampson, M. B., El Sampson, W. B., G15 Sandberg, B. R. , F10 Sarantsev, V. P., A4 Satti, J. A., G36 Sauer, J. R., 125 Sauter, E., Cll Scalise, D. T., G22 Schaffer, G., H13 Schechter, M., B14 Scherr, R. E., B38, H3 Schimmerling, W., F26 Schindl, K. H., C4 Schmelzer, Ch., G39 Schmidt, F. H., B17 Schneider, R., E5, E7 Scholl, R., H13 Schulze, D., Cll Schwedtmann, K., F20 Schweingruber, F. L., H18 Schwettmann, H. A., J4 Sellers, J. F., G5, G8 Selph, F. B., C22, 13 Serre, Ch., H16 Sessler, A. M. , C2, 115, 116 Sharp, J. B., Hll Shaw, K. B., F16 Shaw, J., B19 Sheehan, M. J., C27 Sheehan, J. F., Dig Sherwood, W. A., H9, 127 Siefkes, H., Cll Siegel, R. T., E27 Siegmund, U., 14 Simanton, J. R., H38 Sinclair, C. K., 124, 125 Sluyters, T. J. M. , Bl, C17 Smart, D. L., G33 Smith, B. H., F8, Fll, G33, H26 Smith, L., CI Smith, M. E.,,H9 Smith, P. F., G13 Snowdon, S. C, 12 Snyder, J. N., 17 Sobert, D., B31, H14 Soukas, A. V., C21, G27, H5 Spillecke, H., B14 Spoerlein, R. L. , 121 Srivastava, K. D., B23 Stadler, B., D27 Stapay, J. R„, G36 Steben, J. D., B36 Steinbock, L. , 14 Stephenson, J. M., G7 Stevens, R. R., Jr., B29 Stevenson, G. R., F16 Stewart, C, H21 Stoltz, 0., 112 Strobridge, T. R., J5 Strolin, P., C24 Suelzle, L., 18 Sutton, D. C, 15 Swain, G. R., Hll Swoboda, C, H25 Szesci, L., 112 Tallgren, U. , H8 Tanabe, J., 121 Taylor, A,, B36 Teng, L. C, G2 Terry, F. D., H23 Tetu, P., H8 Thebado, E. A„, F41 Thimmel, H., E18 Things tad, P., F44 Thompson, C. C, B16, B24, B27 Tidrick, G. A., H43, H44 Tigner, M., B35 Tom, J. L., E25 Tomcavage, J. R. , D10 Tool, G. S., Fl Tran, D. T., D24, G28 Trent, P., C20 Tso, T., C25 Tzara, C, D3 Uglum, J. R., B12 Unser, K., H13, H39 Valente, A., H4, H20 Vanderflught, A. G. , G36 Van Buren, D. T. , F19, H40 Van Der Beken, H., H16 Van Der Schueren, A., H8 Van Ness, J. E., G3 Van Nieuwland, J. M. , E13 Van Steenbergen, A., C23, 12 Vetter, J., 113 Veyron, B., D24 Voelker, F., 119 Vogel, H. W., G9 Vogel, U., G26, H30 Voisin, G. , D24 Vorkoeper, D., D23 Vosburgh, K., B31 Walker, S. A., F28 Walsh, T. R., B32 Walter, J. E., G20 Walz, D. R., F29, G38 Watanabe, A. T., D23 Watts, A. R., H7 Weber, D. W., H22 Werner, H. E., B15 Wehrle, R. B., F38 Wells, G. F., B4 Wells, N., B5 Wesolowski, W., E24- Wheeler, G. W., D17 Wliite, W. H., Jr., E9 Williams, C. B., C32 Wilson, E. J. N., C24 Wilson, M. T., F23 Wilson, P. B., J3 Winkler, G., 113 Witkover, R. L., D18 Wolgast, R. C.j H41, HA5 Wolstenholme, P., H13 Worsham, R. E. , E19 Wright, R. E., 121 Wucherer, P., E18 Yang, W., H14 Young, J. D., G29 Younger, F. C., F13 Zajec, E., 121 Ziegler, K., E5, E8 Ziegler, N. F., E19, E20 Zinneman, T., E9, E12 a U. S. GOVERNMENT PRINTING OFFICE : 1 969 — 341 -02Il/l 03 PENN STATE UNIVERSITY LIBRARIES ADDDD7DTDEbSM