Shape evolution in heavy sulfur isotopes and erosion of the N˜28 shell closure

The structure of neutron-rich S nuclei has been investigated through in-beam g-ray spectroscopy using the fragmentation reaction of a 60 MeV A Ca beam on a thin Be target. Eg , Ig , gg-coincidence, and g-ray angular distributions were measured for each produced fragment. The level schemes previously containing only a single g transition were extended, and spin values were proposed for the new states. The experimental results were interpreted by use of microscopic collective-model and large-scale shell-model calculations. The results of the model calculations are consistent with each other, and give a reasonable description of the experimental results. Both models predict an erosion of the N528 shell closure at Z516 and suggest a deformed ground state for S and a spherical-deformed mixed configuration for S.