We derive and calculate the multiple scattering expansion of the Kerman-McManus-Thaler optical potential to second order in the free nucleon-nucleon transition amplitude and clarify the physical content of the interaction. Calculations are presented for the elastic scattering of protons from ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ at 135, 200, and 300 MeV incident energies, paying particular attention to the nonlocalities inherent in the second-order potential. It is shown that these effects result in a significant reduction in the proton-target absorption.

• Received 14 November 1991

DOI:https://doi.org/10.1103/PhysRevC.46.279