Comparing the effects of nonlocal sources on the neutron-nucleus elastic scattering process

Abstract

The wave function of a nonlocal potential is reduced or enhanced in the nuclear interior where the potential acts. This is known as the Perey effect. We use the Perey damping factor to demonstrate that the phenomenological Perey-Buck and the velocity-dependent nonlocal potentials simulate sources of nonlocality. We compare their effectiveness in simulating nonlocal effects by comparing their corresponding Perey damping factors. The importance of the nonlocality arising from the dynamic polarization potential is also estimated by determining the corresponding damping factors. To calculate the needed wave functions corresponding to the local and nonlocal potentials, we determine the parameters of each considered potential by fitting the experimental angular distributions for neutron scattering off nuclei from 6Li to 208Pb for various energies in the range 9 - 35 MeV. Our results show that the nonlocality simulated by each of the three potentials is energy and angular momentum dependent. The effect of the nonlocality simulated by the velocity-dependent potential increases with increasing mass number and, for a given target, becomes more important for higher partial waves. The Perey-Buck potential simulates a nonlocality that is more important for light nuclei. Finally, the nonlocality arising from the dynamic polarization potential increases when more inelastic channels are coupled to the ground state, and becomes more important with increasing energy.