Volume and surface nonlocality terms in the neutron–nucleus elastic scattering using the velocity-dependent optical potential

In this work, we tested the effect of adding a volume term to the surface term in our modified optical potential in the case of elastic neutron scattering of spin-zero 40Ca nucleus in the incident energy range between 30–50 MeV. This is achieved in two steps. First, we fit our theoretical elastic angular distribution scattering using the surface term in our velocity-dependent optical potential concerning the experimental data. Then, we adjust our theoretical elastic angular distribution scattering with the experimental data after adding the volume term into our velocity-dependent optical potential. The second step is comparing the two fits and noticing the effect of adding a volume term to the surface term. Clearly, the modified optical potential using the volume term resulted in excellent fits to the experimental data, most notably the pronounced large angle, backscattering minima, which depend sensitively on the incident energies and which have long been associated with nonlocalities. We assume the nonlocality to be due to interaction between the incident neutrons and the nucleons inside the target.