γ-ray spectroscopy of Ta163

Excited states in Ta163 have been identified for the first time using the Cd106(Ni60,3p) fusion evaporation reaction. γ rays were detected using the JUROGAM γ-ray spectrometer and recoil discrimination was achieved using the recoil ion transport unit (RITU) gas-filled separator in conjunction with the GREAT spectrometer situated at the focal plane of the RITU. The yrast states are assigned to a strongly coupled rotational band based on a πh11/2 configuration. This structure exhibits large signature splitting at low spins that disappears after the paired band crossing because of the alignment of a pair of i13/2 neutrons. This effect is ascribed to triaxial shape changes induced by the core-polarizing properties of the deformation-aligned h11/2 proton and the rotation-aligned i13/2 neutrons. Two additional strongly coupled band structures have been established and are discussed in terms of octupole-vibrational and two-quasiparticle excitations built on the yrast structure. The experimental results are compared with predictions from cranked-shell-model and total-Routhian-surface calculations.