Abstract
The decay of the neutron-rich nuclides, 40-s Xe139, 1.7-s Xe141, and 0.4-s Xe143 to levels of odd-Z Cs139, Cs141, and Cs143, 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 Cs139 including a doublet at 393 keV, and new spin and parity assignments are proposed. New data are presented for Cs141 levels in support of an earlier proposed level scheme by Talbert and Cook. Evidence for a 0.4-s half-life for Xe143 has been found, and a level at 90 keV is proposed for Cs143. 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. © 1988 The American Physical Society.