SHELL-MODEL CALCULATIONS IN THE A = 80-100 MASS REGION .2. A STUDY OF THE N = 49, 48 NUCLEI

The structure of the 38 less-than-or-equal-to Z less-than-or-equal-to 44 and N = 49, 48 nuclei is examined by considering the doubly closed Sn-100(50) as a core and placing proton and neutron holes in the 0g9/2, 1p1/2, 1p3/2 and the 0f5/2 orbitals. The effective interaction for this model space has been derived by introducing second-order corrections to the Sussex matrix elements, while the one-hole energies have been deduced by a least-squares fit to the observed levels. It is found that agreement with experiment can be improved by introducing three parameters which modify the strength of some T = 0 matrix elements. The results of the calculation are found, generally, to be in satisfactory agreement with experiment for most nuclei examined. However, as in the case of the N = 50 nuclei, there are indications that configurations outside the model space begin to influence the low-lying spectra of the N = 49, 48 nuclei as the number of valence holes increases.