High-K isomer and the rotational properties in the odd-Z neutron-rich nucleus M163Eu *

Abstract The newly observed isomer and ground-state band in the odd-Z neutron-rich rare-earth nucleus 163Eu are investigated by using the cranked shell model (CSM), with pairing treated by the particle-number conserving (PNC) method. This is the first time detailed theoretical investigations are performed of the observed 964(1) keV isomer and ground-state rotational band in 163Eu. The experimental data are reproduced very well by the theoretical results. The configuration of the 964(1) keV isomer is assigned as the three-particle state . More low-lying multi-particle states are predicted in 163Eu. Due to its significant effect on the nuclear mean field, the high-order deformation plays an important role in the energy and configuration assignment of the multi-particle states. Compared to its neighboring even-even nuclei 162Sm and 164Gd, there is a 10%~15% increase of of the one-particle ground-state band in 163Eu. This is explained by the pairing reduction due to the blocking of the nucleon on the proton [413] orbital in 163Eu.