Neutron and proton transition densities from S32,34(p,p’) at Ep=318 MeV. I. Isoscalar densities for S32

Differential cross sections and analyzing powers for low-lying states of S-32 were measured using 318 MeV protons. The data were analyzed using an empirical effective interaction previously fitted to inelastic scattering data for O-16 and Ca-40 at the same energy. Transition densities for many states were fitted to the data using general expansions which permit evaluation of uncertainties due to statistical and normalization errors, penetrability and distortion, and incompleteness in momentum space. The accuracy of the procedure was tested by comparing isoscalar densities fitted to (p,p') data for S-32 with proton densities fitted to (e,e') data. The good agreement between these analyses supports the quantitative accuracy of densities fitted to (p,p') data. Isoscalar densities were also fitted to data for several states of S-32 for which no (e,e') data exist. We find that the experimental densities agree well with the shell model for the first 2+ state, but that the neutron density for the second 2+ state is distinctly different in shape. Good qualitative agreement between the data and the shell model is obtained for the first two 4+ states of S-32. Transition densities were also fitted to the data for the lowest 1-, 3-, and 5- states in S-32. The shape of the 1- transition density is complicated, but the very small matrix element agrees with the approximate selection rule that suppresses isoscalar E1 moments.