Multiple band structures in 169,170Re: Search for the wobbling mode in 169Re, and residual-interaction analysis of structures in 170Re

Abstract

Although the observation of wobbling was once thought to be possibly confined to lutetium isotopes in N?94 nuclei, the identification of this exotic collective mode in 167Ta has raised the question of the role of the proton Fermi surface with regard to this phenomenon. To investigate this issue, an experiment was performed to populate high-spin states in the N=94 nucleus 169Re. The heavy-ion reaction 55Mn+118Sn was used in conjunction with Gammasphere to detect the emitted ? rays. More than 130 new transitions were added to the 169Re level scheme, including the first identification of the ?i13/2 rotational sequence in this nucleus. This configuration is the structure on which all known wobbling sequences are based, but no wobbling band was observed, likely owing to the fact that the ?i13/2 sequence is located at a relatively high energy in comparison with the other structures found in 169Re. Nine decay sequences are now established in this nucleus and are described within the context of the cranked shell model. In addition, significant extension of the level scheme of the odd-odd 170Re nucleus was possible and a discussion of the residual interactions for the ?h 9/2?i13/2 and ?i13/2?i13/2 configurations in this region is given as well. �2013 American Physical Society.