Competition between high-K states and rotational structures in 177Ta

Abstract

High-spin states in 177Ta have been studied using the 170Er(11B,4n) reaction. New intrinsic states have been observed corresponding to 3-, 5-, and 7-quasiparticle high-K structures. Rotational bands built on most of the 3-and 5-quasiparticle states and some transitions above the 7-quasiparticle states have been identified. Several isomers have been found, the longest lived being the 49/2-, 7-quasiparticle state with a meanlife of 192 μs. Configurations for the observed intrinsic states have been assigned on the basis of gK values, alignments, and decay properties. While the properties of most of the bands are consistent with their proposed configurations, the behavior of some, including the one built on Kπ = 21/2- 3-quasiparticle isomer, is not well understood. Multiquasiparticle blocking calculations based on the Lipkin-Nogami method, are in good agreement with the excitation energies of the experimentally observed states and all the predicted states close to the yrast line up to spin 49/2 have been observed experimentally. The calculations predict the existence of a 9-quasiparticle 67/2- yrast trap at ∼ 8.5 MeV.