Nucleon elastic scattering potentials: Energy and isospin dependence

Volume integrals of the real potentials derived from proton elastic scattering studies have been calculated for data available from the lowest to the highest energy. Because of the spread of the volume integrals at low energies, an average of volume integrals in each 1 MeV bin was calculated. These average volume integrals show a logarithmic dependence on the beam energy. A similar analysis of neutron potentials shows that the proton energy dependence can be applied to neutron data. The data for proton scattering from Ca isotopes at 1044 MeV were analyzed in terms of the optical model, and an isospin component of the potential was determined. The derived isospin potential is compared with those obtained for proton and neutron scattering in previous investigations.