gamma-ray spectroscopy of a four-quasiparticle isomer band in Re-174

Excited states in Re-174 have been populated in fusion-evaporation reactions at the Australian National University, and gamma-ray spectroscopy has been used to determine the level structure and to deduce the underlying nucleon configurations. The half-life of the bandhead of the K-pi = 8(-) band has been measured to be 2.7(4) ns. A band built on an isomeric state of spin-parity (14(-)) and a half-life of 53(5) ns has been observed here for the first time, and has been determined to have a four-quasiparticle structure. Contrasting reduced-hindrance values for its decay are discussed in terms of deformation and configuration changes, as indicated by configuration-constrained potential energy surface calculations.