DIRECT MEASUREMENTS OF THE HALF-LIVES OF SOME SHORT-LIVED XENON AND CESIUM ISOTOPES

Experimental techniques that are useful in the production and study of the fission product rare gases have been developed. The experimental developments reported in this work include a new radiation-resistant fission-gas-emanating compound, a fast technique for the separation of trace quantities of xenon or krypton from a fission gas mixture, and a "charged-wire chamber" used in the continuous removal of decay products from radioactive gas sources.These methods have been applied in the determination, by direct counting techniques, of the half-lives of 138 Cs (32.3 ± 0.1 min), 139 Cs (9.0 ± 0.15 min), 140 Cs (63.8 ± 1.2 sec), 137 Xe (3.80 ± 0.05 min), 139 Xe (14.1 ± 0.8 min), 139 Xe (41.2 ± 0.15 sec), and 140 Xe (13.7 ± 0.15 sec). These results compare favorably with the most recently published measurements of these half-lives.