Alignment of individual-particle angular momenta along the deformation axis in light nuclei

Abstract

High- K rotational bands which are based on deformation-aligned multiparticle configurations of the Nilsson-model are shown to provide levels on or close to the yrast line in the s – d shell nuclei between 23 Na and 29 Si . The evidence is based on experimental data amended by results of shell model calculations which yield level energies and matrix elements of the E2 operator with proven reliability. The phenomenon of deformation alignment is completely contained in the shell model. The low excitation energies of deformation aligned states are traced back to the p – n interaction in the T=0 channel which favours parallel alignment of angular momenta. The proof uses Nilsson-model matrix elements of the residual interaction which are deduced from the experimental properties of low- K bands by a method which is due to Brink and Kerman.