PAIRING EFFECTS IN SN ISOTOPES

An extensive study of pairing effects in the Sn isotopes is carried ou t. The pairing Hamiltonian is treated by the chain-calculation method which provides practically exact solutions while involving less comput ational work than a complete-basis diagonalization. The coupling stren gth is fixed by reproducing the energy of the 9(-) state in Sn-116, wh ile the single-particle energies have been determined by an analysis o f the experimental low-energy spectra of the odd-A isotopes. A detaile d comparison of the calculated results with experimental data evidence s the importance of neutron pairing correlations in the 50-82 shell. T he results of this paper complement those of our previous study of the N = 82 isotones. It turns out that the role of pairing correlations i s similar to a large extent in both cases.