Isospin excitation and shape phase transition in odd-mass Cu isotopes

Abstract

In this paper, the interacting boson–fermion model generalized by considering an np-boson and the single nucleon as a vector coupled in isospin to the bosons to form the model isospin invariant. The transitional interacting boson–fermion model Hamiltonians in IBFM-1 and IBFM-3 versions based on affine SU(1,[Formula: see text]1) Lie algebra are employed to describe the evolution from the spherical to deformed gamma unstable shapes along the chain of Cu isotopes. We have studied the energy spectra of [Formula: see text] isotopes and B(E2) transition probabilities of [Formula: see text] isotopes in the shape phase transition region between the spherical and gamma unstable deformed shapes. Good agreement was achieved between the calculated results using the models and measured data. The results obtained and the values of control parameters used in this calculation indicated that the odd-mass Cu isotopes located near the closed shell provided good examples of [Formula: see text](5) symmetry without any significant deformed gamma-unstable structure. Some comparisons are made with IBFM-1.