Triaxial projected shell model study of gamma-vibrational bands in even-even Er isotopes

摘要

We expand the triaxial projected shell model basis to includetriaxially-deformed multi-quasiparticle states. This allows us to study theyrast and gamma-vibrational bands up to high spins for both gamma-soft andwell-deformed nuclei. As the first application, a systematic study of thehigh-spin states in Er-isotopes is performed. The calculated yrast andgamma-bands are compared with the known experimental data, and it is shown thatthe agreement between theory and experiment is quite satisfactory. Thecalculation leads to predictions for bands based on one- and two-gamma phononwhere current data are still sparse. It is observed that gamma-bands forneutron-deficient isotopes of 156Er and 158Er are close to the yrast band, andfurther these bands are predicted to be nearly degenerate for high-spin states.