Conversion-coefficient measurements and spin-parity assignments for excited levels in Xe133,135,136, Cs135,137,139, and Ba138

Abstract

Solid-state detectors have been used to perform on-line measurements of -ray and conversion-electron intensities in Xe133,135,136, Cs135,137,139, and Ba138. Conversion coefficients were determined for 37 transitions. Logft values were calculated on the basis of reported level schemes. The deduced multipolarities and logft values were combined with published reaction and angular-correlation results to assign spins and parities to 24 excited levels of the mentioned nuclei. The obtained J contributed 13 new experimentally-well- defined -transition probabilities to the systematics of this magnitude. In Xe136 and Ba138, three levels with known half-lives were determined to be depopulated by pure-E2 transitions; the retardation factors as compared to the Weisskopf estimate were calculated. Apart from J assignments, some additional minor contributions were made to the knowledge of the level structure in Ba138 and Cs139. The number of possible spins and parities for some of the excited levels in the nuclei studied was reduced by analyzing the systematic trends of measured J values in their neighborhood. No modelistic considerations were taken into account for this purpose. © 1972 The American Physical Society.