Quadrupole-octupole collective excitations in medium mass nuclei

Abstract

A quadrupole-octupole axially symmetric collective model is used to describe the alternate parity bands observed in even-even medium mass nuclei. The nature of the octupole correlations in considered nuclei is ascertained from the phenomenology of the adopted model and the obtained parameters. It is found that the model parameters have a regular evolution as a function of neutron number, suggesting that the shape phase transition around N = 90 from low to well deformed shapes is also accompanied by the increase of the vibrational character for the octupole deformation. Model extrapolations are performed for various types of excited states and electromagnetic properties of measured energy levels.