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U.S. Department of Energy
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International program to improve decay data for transactinium nuclides

Conference ·
OSTI ID:5599338

To help meet an identified need for precise decay data, in 1977 the IAEA organized an international Coordinated Research Program (CRP) to measure and evaluate half-lives and ..gamma../sup -/ and ..cap alpha../sup -/ emission probabilities for selected transactinium nuclides of importance for reactor technology. The CRP goals were (1) to determine a list of data that needed improvement, (2) to encourage new measurements, and (3) to evaluate the available data. All three phases of this work are now complete. Our participation in this effort has involved the measurement of ..gamma..-ray emission probabilities for /sup 232, 233, 235/U, /sup 238, 239, 240, 241/Pu, /sup 229/Th and /sup 233/Pa, as well as participating in the data evaluation. The ..gamma..-emission probabilities were determined from the measurement of ..gamma..-emission rates with the goal of obtaining uncertainties of less than or equal to 1%. ..gamma.. measurements were made on calibrated Ge detectors. These calibrations were done by standard methods, generally involving measurements at approx. 60 ..gamma..-ray energies from 14 to 2700 keV. The efficiency-calibration functions were assigned uncertainties ranging from 2% below 50 keV to 0.50% from 400 to 1400 keV. The determination of the decay rates of the various sources involved several techniques. The /sup 238/Pu, /sup 239/Pu and /sup 240/Pu samples were calibrated by gross ..cap alpha..-emission-rate measurements at NBS. The /sup 235/U sample was taken from an NBS-calibrated spike solution. The /sup 241/Pu and /sup 233/U samples were calibrated by isotope-dilution mass spectrometry based on spikes of the calibrated /sup 239/Pu, /sup 240/Pu and /sup 235/U materials. Some of our results are given, together with a comparison of some present and previous results. 20 refs.

Research Organization:
Idaho National Engineering Lab., Idaho Falls (USA)
DOE Contract Number:
AC07-76ID01570
OSTI ID:
5599338
Report Number(s):
EGG-M-08085; CONF-850533-4; ON: DE85011258
Country of Publication:
United States
Language:
English