Optical-Model Analysis of 30-MeV Proton Scattering

Elastic cross sections together with polarization data and reaction cross sections for the interaction of 30-MeV protons with ${\mathrm{Ca}}^{40}$, ${\mathrm{Fe}}^{56}$, ${\mathrm{Ni}}^{58}$, ${\mathrm{Co}}^{59}$, ${\mathrm{Ni}}^{60}$, Cu, ${\mathrm{Sn}}^{120}$, and ${\mathrm{Pb}}^{208}$ have been analyzed using the optical model. It was found possible to obtain good fits to all the experimental data with a single set of geometrical parameters involving one diffuseness value but different radius parameters for the real central, the imaginary central, and the spin-orbit potentials. The new features revealed by this analysis include (1) a spin-orbit radius parameter less than the corresponding central values and (2) an imaginary diffuseness larger (0.7 F) than that required at lower energies (≈0.5 F).