Crossing of the $\pid_{5/2}$ and $\pig_{7/2}$ orbitals in the $_{51}$Sb isotopes
Résumé
Self-consistent calculations using the D1S Gogny force have been performed in order to study the mechanism involved in the crossing of the $\pid_{5/2}$ and $\pig_{7/2}$ orbitals in the Sb isotopes. This inversion is well predicted by the HFB + blocking calculations with spherical symmetry performed for the odd-A Sb isotopes. In addition, several HFB and HF calculations have been performed for even-even nuclei of the five neighbouring isotopic chains (Z = 46 to 54, from the proton dripline to N = 82). The results obtained for the binding energies of the two proton orbitals indicate that the radii of the systems play an important role in the crossing, even though some particular πν interactions also give a contribution. The spin-orbit interaction, which is known to be concentrated mainly at the nuclear surface, is proposed to be the main responsible of the crossing.