Signature property of odd- A nuclei in the interacting boson-fermion model

Abstract

The signature dependence of energy levels and electromagnetic transitions (E2 and M1) in odd- A nuclei is studied in terms of the interacting boson-fermion model (IBFM). The odd- A nucleus is treated in the IBFM as a system of odd particles (fermions) coupled with boson cores described by the interacting boson model (IBM). There are three dynamical-symmetry limits in the IBM, and the boson cores in such limits are shown to produce different signature dependences in the IBFM. We also discuss the effects of the boson-fermion quadrupole-quadrupole and exchange interactions on the signature dependence. We then apply the IBFM to the nuclei 173Yb, 157Ho, 165Lu and 163Dy. The signature dependence observed in some of these nuclei resembles the one obtained with the boson core in one of the dynamical-symmetry limits. Including such cases, the IBFM describes various signature dependences in a unified way. The nucleus 173Yb is characterized by the SU(3) core, while the other three nuclei show situations between the O(6) and the SU(3) limits. The single-particle orbit π h 11 2 or ν f 7 2 is considered for the odd particle, except 163Dy where two single-particle orbits h 9 2 and f 7 2 are introduced. The results are compared with those of the rotating shell model and the particle-rotor model.