2s1/2 occupancies in 30Si, 31P, and 32S

Elastic electron scattering off 30Si and 31P was studied in an effective momentum-transfer range of 1.8 endash 3.0 fm-1. The form-factor data were analyzed together with existing data sets for these nuclei and for 32S in a model-independent Fourier-Bessel expansion. For 31P the M1 contribution was subtracted following an established parametrization. Results of Hartree-Fock (HF) calculations, performed for these three nuclei in a spherical basis and in an axially deformed basis, are compared to experiment. Occupancies have been determined which, when used in the spherical-basis HF calculations, lead to a good description of the elastic form-factor data. The deformed-basis calculations have been used to study the influence of the deformation on the calculated binding energies and ground-state charge densities. In all calculations the influence of using different effective nucleon-nucleon interactions was investigated. The resulting differences in 2s1/2 in occupancy are combined with results from previous existing (e,e'p) experiments to yield open-quotes absolute occupanciesclose quotes for the 2s1/2 orbital. The deduced 2s1/2 occupancies for 30Si and 32S are 0.24(4) and 1.35(19), respectively. copyright 1997 The American Physical Society