In this article we report on the first spectroscopic information on Sb8951140 and the observation of an isomer in this nucleus with T1/2=41(8) μs. It is located in close proximity to Sn140 for N=90, where the νf7/2 orbit is completely filled. The possible origin of the isomeric state is a πg7/21×νf7/2-1 coupling configuration, resulting in a (6-) or (7-) spin-parity. This is likely caused by an inversion of the πg7/2 and πd5/2 orbitals at N=89. The existence of such an isomer far from stability is discussed extensively in the context of shell-model calculations and compared to results from mean-field calculations performed using a deformed Woods-Saxon potential. Both approaches suggest the observation of a single-particle excitation mode at an extreme neutron number.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics