On the energy dependence of the imaginary optical-model potential for proton scattering from 40Ca

Abstract

The energy dependence of the imaginary potentials for proton elastic scattering from 40Ca has been derived on the basis of the Feshbach formalism by taking into account the coupling with the inelastic and pick-up channels to the elastic channel. It is found that the calculated potential describes quite well the experimental differential and absorption cross sections for incident energies between 10 MeV and 50 MeV. However, at high energies above 50 MeV, the calculated imaginary potentials seem to be inadequate. We assume a Woods-Saxon form for the real part of the potential, the parameters of which are in good agreement with phenomenological values, if finite-range calculations are made for the p-d-p process. The local potentials equivalent to the non-local potentials are also calculated and are compared with the phenomenological imaginary potentials.