Semiclassical Treatment of the Interaction Between Individual and Quadrupole Collective Degrees of Freedom

摘要

Two types of interactions between a system of paired spherical shell model nucleons and a phenomenological quadrupole vibrational core are semiclassically treated. One induces a specific dependence of the gap parameter on the core's angular momentum while the other one renormalizes the single particle energies by a beta exp 2 -term. The former case enables one the interpretations for a sequence of states of the same angular momentum J - horizontal band -as RPA - multiphonon states describing vibrations of small amplitudes around the ground state J exp + . A vertical band J, J+2, ... is built by an approximative projection of angular momentum from a variational trial function. Application to exp 188 Pt shows a good agreement with experiment. The second type of interaction renormalizes the energy of the quadrupole mode and shifts the zero point energy. Using the phase space coordinates one defines three distinct boson representation for the quasi-spin operators, which are useful for improving the RPA approach. One concludes that the particle-core interaction affects essentially not only the states lying beyond the crossing point of yrast collective and 2qp bands but also the low lying collective states. (Atomindex citation 15:066028)