Decay of139,141,143Xe to levels of139,141,143Cs

Abstract

The ..beta.. decay of the neutron-rich nuclides, 40-s /sup 139/Xe, 1.7-s /sup 141/Xe, and 0.4-s /sup 143/Xe to levels of odd-Z /sup 139/Cs, /sup 141/Cs, and /sup 143/Cs, respectively, has been studied using sources isolated from fission products by on-line mass separation. The data collected include gamma-ray and conversion electron singles spectra as well as gamma-ray coincidence and angular correlation spectra. New levels have been identified in /sup 139/Cs including a doublet at 393 keV, and new spin and parity assignments are proposed. New data are presented for /sup 141/Cs levels in support of an earlier proposed level scheme by Talbert and Cook. Evidence for a 0.4-s half-life for /sup 143/Xe has been found, and a level at 90 keV is proposed for /sup 143/Cs. The resulting level structures for the neutron-rich Cs nuclides are compared with level structures of other odd-Z neutron-rich nuclides and neutron deficient Cs nuclides. The transition from the structure observed near the closed N = 82 neutron shell to deformed structures described by Nilsson model orbitals is discussed.