Precision Measurement of Half-Lives and Specific Activities of 235U^{235}\mathrm{U}235U and 238U^{238}\mathrm{U}238U (original) (raw)
Abstract
New determinations of the half-lives of U235 and U238 have been made. Improved techniques have allowed the half-life values to be measured with greater accuracy than has been heretofore achieved. Samples were prepared by molecular plating and counted in a intermediate-geometry α-proportional counter with an extremely flat pulse-height plateau. The small amount of residual nonplated uranium was counted in a 2π counter. Energy analysis with a silicon-junction detector was used to measure the presence of "foreign" activities. For U235, the measured specific activity was (4798.1±3.3) (dis/min)/(mg U235), corresponding to a half-life of (7.0381±0.0048) × 108 yr. For U238, the specific activity was measured as (746.19±0.41) (dis/min)/(mg U238), corresponding to a half-life of (4.4683±0.0024) × 109 yr. Errors quoted are statistical (standard error of the mean), based upon the observed scatter of the data. This scatter exceeds that expected from counting statistics alone. We believe that systematic errors, if present, will no more than double the quoted errors.
- Received 29 April 1971
DOI:https://doi.org/10.1103/PhysRevC.4.1889
©1971 American Physical Society
Authors & Affiliations
A. H. Jaffey, K. F. Flynn, L. E. Glendenin, W. C. Bentley, and A. M. Essling
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
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