SHELL-MODEL CALCULATIONS IN THE A = 80-100 MASS REGION .1. A STUDY OF THE N = 50 NUCLEI

The structure of the N = 50 and Z < 50 nuclei is examined in a model space consisting of the 0g9/2, 1p1/2, 1p3/2 and the 0f5/2 proton-hole orbitals outside the doubly dosed Sn-100(50) core. The effective two-body interaction and the effective one-body transition operators for this model space are derived by introducing second-order corrections to the Sussex matrix elements, while the one-hole energies are deduced by a least-squares fit to the observed levels. The results of the calculation are found to be in very satisfactory agreement with experiment for all nuclei with 38 < Z less-than-or-equal-to 46 but for Z less-than-or-equal-to 38 this agreement begins to deteriorate rapidly. Such a feature possibly indicates the appearance of deformation and the breaking of the N = 50 core.