A semi-phenomenological spherical optical model potential for elastic scattering of nucleons

In this work we present a semi-phenomenological spherical optical model potential (OMP), for elastic scattering of incoming neutrons or protons on A 40 nuclei, up to 200 MeV. The central part of this OMP is formally identical to that derived by Jeukene, Lejeune and Mahaux (JLM) from Br ucknerHartree-Fock calculations in nuclear matter. However, discontinuities in the parametrisations of the imaginary part of the JLM OMP at 10 MeV, and the pathology exhibited by the imaginary part of this OMP when extrapolated above 160 MeV, led us to ret the imaginary part of the JLM nuclear matter potential. For the spin-orbit (SO) potential, we use a phenomenological complex SO potential with a Scheerbaum form factor, permitting us to get good ts to the experimental di erential cross sections and analyzing powers, up to 185 MeV. We then allow the normalizations of the potentials depths to vary as a function of energy in order to get the best t to experimental elastic scattering data, and we express these variations with a functional form, thus getting a global OMP for nucleons up to 200 MeV. This global OMP, built using point proton and neutron radial densities calculated in the Hartree-Fock-Bogoliubov (HFB) framework with the Gogny force, is able to account fairly well for the experimental angular distributions and reaction cross sections, provided the target nucleus is spherical (i.e., Ca, Zr, Nb, Sn, Sn, Pb, Bi) or quasi-spherical (i.e., Fe, Fe, 58 Ni, Ni, Cu, Cu).