Multi-quasiparticle γ-band structure in neutron-deficient Ce and Nd isotopes

The newly developed multi-quasiparticle triaxial projected shell model approach is employed to study the high-spin band structures in neutron-deficient even–even Ce- and Nd-isotopes. It is observed that γ-bands are built on each intrinsic configuration of the triaxial mean-field deformation. Due to the fact that a triaxial configuration is a superposition of several K-states, the projection from these states results in several low-lying bands originating from the same intrinsic configuration. This generalizes the well-known concept of the surface γ-oscillation in deformed nuclei based on the ground-state to γ-bands built on multi-quasiparticle configurations. This new feature provides an alternative explanation on the observation of two I=10 aligning states in 134Ce and both exhibiting a neutron character.