Energy levels and configuration interaction in Zr 90 and related nuclei

Abstract

Proton and neutron p 1 2 and g 9 2 configurations (and in particular the interaction of the two 0 + states in Zr 90) are considered without any specific assumptions on the two-body nuclear interaction and radial function and radial functions. Matrix elements of the effective nuclear interaction are determined by the analysis of energy levels in Zr 90 and several neigbouring nuclei (e.g. Sr 86 which has the same configurations). Good agreement is obtained between calculated and experimental level spacings. The one non diagonal matrix element is determined along with the diagonal elements and the amount of admixture is calculated in all cases. The ground state of Zr 90 is found to be 75 % in the p 1 2 2 configuration and 25 % in the g 9 2 2 configuration in agreement with the rough experimental findings. The seniority is found to be a good quantum number for the effective interaction obtained in the g 9 2 shell of identical nucleons. This interaction gives rise to the low lying 7 2 + level in Sr 85. Level schemes predicted by the present calculation are given for several nuclei.