HALF-LIVES OF SOME SHORT-LIVED MASS-SEPARATED GASEOUS FISSION PRODUCTS AND THEIR DAUGHTERS

The half-lives of several short-lived isotopes of Kr, Rb, Sr, Xe, Cs and Ba have been measured using sources of isotopically pure Xe or Kr and multi-scaling selected transitions in the Ge(Li) gamma-ray spectra of their decays. Beta-ray multi-scaling was employed to confirm the gamma-ray multi-scaling results in several cases. The results of the measurements are (in sec) 89Kr, 190.7±1.4; 89Rb, 909±7; 90Kr, 32.32±0.09; 90Rb, 153±3 and 251±10; 91Kr, 5.87±0.04; 91Rb, 58.2±0.2; 92Kr, 1.840±0.008; 92Rb, 4.50±0.03; 93Kr, 1.289±0.012; 93Rb, 5.86±0.13; 93Sr, 439±6; 137Xe, 229.1±0.8; 138Xe, 850±4; 138Cs, 1932±12; 139Xe, 39.68±0.14; 139Cs, 556±3; 140Xe, 13.60±0.10; 140Cs, 63.7±0.3; 141Xe, 1.720±0.013; 141Cs, 24.7±0.4; 141Ba, 1096±4; 142Xe, 1.24±0.02; 142Cs, 1.68±0.02 and 142Ba, 639±7. The existence of an isomeric state in 90Rb is indicated by the result spectrum multi-scaling. In most cases, these results compare favorably with recently published values of these half-lives. © 1969.