Interplay between pairing and tensor effects in the N = 82 even–even isotone chain

The combined effects of the pairing and tensor terms of the nuclear interaction are investigated by analyzing the ground state properties of the nuclei belonging to the isotonic chain N=82N=82. The pairing effects have been taken into account by considering both Hartree–Fock–Bogoliubov and Hartree–Fock plus Bardeen–Cooper–Schrieffer approaches using the same finite-range nuclear interaction, specifically a force of Gogny type. Our results reproduce very well the available experimental data of binding energies and charge radii. The study of the particle number fluctuation indicates that the presence of the tensor terms in the interaction reduces the pairing effects and produces new shell closures in some isotopes. The experimental behavior of the energy difference between neutron single particle states up to A=140A=140 is properly described only if the tensor force is considered.