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

Although the observation of wobbling was once thought to be possibly confined to lutetium isotopes in N approximate to 94 nuclei, the identification of this exotic collective mode in Ta-167 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 Re-169. The heavy-ion reaction Mn-55 + Sn-118 was used in conjunction with Gammasphere to detect the emitted gamma rays. More than 130 new transitions were added to the Re-169 level scheme, including the first identification of the pi i(13/2) 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 pi i(13/2) sequence is located at a relatively high energy in comparison with the other structures found in Re-169. 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 Re-170 nucleus was possible and a discussion of the residual interactions for the pi h(9/2)nu i(13/2) and pi i(13/2)nu i(13/2) configurations in this region is given as well. DOI: 10.1103/PhysRevC.87.024315