Neutron Skin Thickness of Ca 48 from a Nonlocal Dispersive Optical-Model Analysis

A nonlocal dispersive optical-model analysis has been carried out for neutrons and protons in Ca48. Elastic-scattering angular distributions, total and reaction cross sections, single-particle energies, the neutron and proton numbers, and the charge distribution have been fitted to extract the neutron and proton self-energies both above and below the Fermi energy. From the single-particle propagator resulting from these self-energies, we have determined the charge and neutron matter distributions in Ca48. A best fit neutron skin of 0.249±0.023 fm is deduced, but values up to 0.33 fm are still consistent. The energy dependence of the total neutron cross sections is shown to have a strong sensitivity to the skin thickness.