Description of nuclear octupole and quadrupole deformation close to the axial symmetry: Octupole vibrations in the X(5) nuclei 150Nd and 152Sm

摘要

The model, introduced in a previous paper, for the description of theoctupole and quadrupole degrees of freedom in conditions close to the axialsymmetry, is used to describe the negative-parity band based on the firstoctupole vibrational state in nuclei close to the critical point of the U(5) toSU(3) phase transition. The situation of 150Nd and 152Sm is discussed indetail. The positive parity levels of these nuclei, and also the in-band E2transitions, are reasonably accounted for by the X(5) model. With simpleassumptions on the nature of the octupole vibrations, it is possible todescribe, with comparable accuracy, also the negative parity sector, withoutchanging the description of the positive-parity part.