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169
CANLY-161
üanya-Ray Branchings in the Decay or 110in, 141ce, and 141na*
James S. Eldridge, Peter Crowther * and william S. Lyon, Jr.
Absolute gamma-ray branchings have been determined for three important
muclides: 10 In, 144ce, and 14 na. These branchings are necessary for techniques
AUG 1 3 1904
of isotopic analysis and absolute disintegration-rate determinations utilizing
methods described by Lazar').
Sources or in were prepared by 10-sec irradiations of 2 mg samples of
purified indium in the pneumatic facility of the Oak Ridge Research Reactor (ORR).
A least-squares analysis of data obtained by following the decay of gamma-rays
over a period of ten half-lives resulted in a half-life value of 53.73 # 0.06
minutes. Sources of isotopically pure Ce were obtained by irradiation of
La o, in a high-flux position of the ORR. The **Ce was produced by double
neutron-capture by +39 La followed by negatron decay of the 3.5-2 tla. High
specific activity + 'Nd was obtained from the Isotopes Division, ORNL, and further
purified by ion exchange separation.
Absolute disintegration-rate determinations were made using 47 Boy coincidence-
counting techniques as described by Campion ), Garma-ray emission rates were
determined for each muclide with a 512-channel analyzer and 3-in by 3-in NaI(Ti)
detector. Graphical techniques described by Heath'3) were used to resolve gamma-
rays in the spectra of Dº In and 147Na. Bianching ratios were then calculated
by dividing the gamma emission rates by the absolute disintegration rate for
each source.
Absolute gamma branchings for the three muclides are presented in Table I.
In each case, previous workers have given relative values only or there, he Ye RELEASE - OFFICIAL
been discrepancies in the work of several authors').
irri TIC'N WAY BE MADE OFFICIAL
2.0 (JIS MAY BE FILL. REPORT
TCNSINS NOTHING OF PAIENT INTEREST.
PROCLOURES ON FILE IN RECEIVING
Research sponsored by the U. S. Atomic Baergy Commission under contract with
SECTION,
the Union Carbide Corporation,
* Present address: South African Atomic Energy Board, Pelindaba, South Africa
References
1. Lazar, N. H., "Analysis of Gamma Ray Scintillation Spectra for Quantitative
Photon Intensities," IRE Truns. Muc. Sci., NS-5, No. 3, 138 (1958).
campion, P. J., "The Standardization of Radioisotopes by the Beta-Gamma
Coincidence Method Using High Efficiency Detectors," Int. J. Appl. Raj.
Isotopes, , 232 (1959).
Heath, R. L., "Scintillation Spectrometry-Gamma-Ray Spectrum Catalogue,"
IDO-16408, Phillips Petroleum Company (1958).
3.
4.
Muclear Data Sheets, National Academy of Sciences - National Research Council,
Washington, D. C.
TABLE I
116
Genunn Branchingis l'or **It
by 116 n. lll2ce, 191%Na
1
'No
Nuclide
Gaume-Ray linergy (MeV)
Gamma-Branching (Y/8)
110 In
1.09
0.5190
1.20
0.058
1.49
0.070
1.77
0.041
2.09
0.169
Ilizce
0.145
0.493
147 Na
1.0913
0.270
0.277
0.008
0.321
0.022
0.400
0.013
0.441
0.009
0.533
0.134
0.688
0.007
DATE FILMED
12/31 764




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