Competition between Pairing and Quadrupole Deformation in the Yrast Sequence of^150,152Dy

Abstract

The yrast spectra are investigated for the non-collective nuclei 150i152D Y using the Nilsson-Strutinsky + blocked BCS model. The separate effects from the pairing force and the quadrupole force (deformation changes) are studied. It is found that the pairing force is important in describing the yrast line up to I -30, while the quadrupole force is important for I,> 20. The calculated increase of the oblate deformation with increasing spin is expained as an antipairing effect when only valence nucleons are building the total spin and as a polarization effect when the core becomes excited.