HALF-LIFE OF Cs¹³⁷

Abstract

The half-life of Cs13I was found to be 30.4k0.4 years by determining the amount of Bala7 produced in various times from a known number of CslS7 atoms. The numbers of barium and cesium atoms were determined from isotope dilution data obtained with a mass spectrometer.

Cumulative yields of the heavy fragments in U235 thermal neutron fission

“…Both these effects have been discussed by Irish (1956) who concluded from measurements made on neodymium that this electron multiplier caused no mass discrimination. Analyses of terrestrial barium isotopes, which were made in conjunction with the measurement of the 137 half-life of Cs (Farrar et al, 1961), gave relative abundances in exchange column to remove cationic impurities. This water was then redistilled twice in an all-quartz still.…”

“…The mass-yield curve for u238 fast fission fortunately does not differ appreciably from that of u255 except in regions of symmetric and very asymmetric fission and hence the corrections are significant in this work only for samarium and europium. (Farrar et al 1961) and 12.80 days (Engelkemeir et al 1951) respectively e) The ratio shown is the weighted average of measurements corrected for decay of Ba^9 and Ba-*-^° to a time 2 hours after removal from the reactor f) Assuming that Ba^39 has an independent yield 1,1% of the total chain yield (Ferguson 1959) and a half-life 82.9 minutes (Butler and Bowles 1958) 140…”

“…Cs(Farrar et al, 1961). Contamination of the samples with terrestrial barium made small contributions to the spectrograms at mass numbers 137 and 138; this, however, was easily subtracted since terrestrial barium also contains Ba1^ and Ba1^ which are not formed appreciably in fission.…”