Mean field calculations of nucleon-nucleus scattering

Corrections to the first order term of the multiple scattering expansion of the nucleon-nucleus optical potential due to the propagation of the projectile nucleon in the target nucleus mean held are estimated. The effects of nonlocalities of the nucleon-nucleon transition amplitude are included. Calculations are performed for nucleon scattering from O-16 and Pb-208 at 100, 200 and 400 MeV incident energies. We show that the mean field effect is repulsive and reduces the strength of the local representation of the impulse approximation potential by approximately 25% in the nuclear interior.