Pairing effects inN=82isotones

The importance of pairing effects in the N=82 isotones is extensively investigated by studying the string of nuclei with A ranging from 135 to 151. The pairing Hamiltonian is treated by an equations-of-motion method which is strictly number conserving. The coupling strength is determined by an analysis of the properties of the even-mass isotones. The single-particle energies are extracted from the experimental spectra of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$ and ${}_{}{}^{145}{}_{}{}^{}\mathrm{Eu}$ through use of the equations which give the energies of the seniority-one states in a way which is analogous to the inverse gap equation method. A detailed comparison of the calculated results with experimental data in even and odd nuclei provides firm evidence of the prominent role of proton pairing correlations in the 50–82 shell. It is found that non-negligible correlations are present in ${}_{}{}^{146}{}_{}{}^{}\mathrm{Gd}$.