Optical-Model Analysis of Proton Elastic Scattering in the Range of 9 to 22 MeV

For incident proton energies between 9 to 22 Mev, 35 elastic scattering angular distributions were analyzed with the optical model using a least-square criteria over the complete angular range of the data. The observed increase of the real well depth as a function of mass number is explained by the presence of a nuclear symmetry term in the potential and by the momentum dependence of the potential. The polarization and reaction cross-section data are in good agreement with the calculations. The effect of core excitations on the parameters of the optical model are studied, and the relative importance of volume and surface imaginary potentials is discussed. Formulas are given to obtain the value of the parameters of the optical model as a function of mass number and energy. (auth)