Asymmetry dependence of proton correlations

A dispersive-optical-model analysis of p+Ca40 and p+Ca48 interactions has been carried out. The real and imaginary potentials have been constrained from fits to elastic-scattering data, reaction cross sections, and level properties of valence hole states deduced from (e, e′p) data. The surface imaginary potential was found to be larger overall and the gap in this potential on either side of the Fermi energy was found to be smaller for the neutron-rich p+Ca48 system. These results imply that protons with energies near the Fermi surface experience larger correlations with increasing asymmetry.