Structure of beta-decaying isomers in deformed, odd-odd ^102,104Nb nuclei^*

Properties of neutron-rich nuclei in the A~100 mass region are important for achieving better understanding of the nuclear structure where the knowledge is limited due to difficulties in the production of these nuclei with high purity and intensity. They are an essential ingredient in the interpretation of the r-process nucleosynthesis and are needed in fission-like applications which depend sensitively on the nuclear structure data input.



We have initiated a dedicated beta-decay spectroscopy program at Argonne National Laboratory, by combining the CARIBU radioactive beam facility with the newly developed Gammasphere decay station. The focus of the present studies was on deformed, odd-odd ^102,104Nb nuclei, where b^- decays of both the ground states and excited spin-traps isomers were investigated. Because of the large spin difference between the ground states and the isomers, a variety of structures in the daughter nuclei were selectively populated and characterized, which in turn provided information about the structure of the parent states. The new data are compared with predictions from deformed, multi-quasiparticle blocking calculations and systematics of known single-particle states in the region, which allowed to elucidate the structure of the beta-decaying states. Differences with previous studies, including recent results obtained from the low-resolution total gamma-ray absorption technique, will also be discussed.