Optical-model calculations with a realistic nucleon-nucleon interaction: (I). Theory

Abstract

The real parts of the optical potentials for the elastic scattering of 65 MeV protons on 16O, 17O and 18O are calculated in an impulse approximation. The prescription used is derived from three-body theory, considering the system as consisting of the incident nucleon, an active bound nucleon, and an inert core. The effective interaction resulting is a fully off-shell T-matrix and is both non-local and energy dependent. Reid's soft-core potential is used to generate the requisite T-matrices. Antisymmetry between the incident and active nucleon is included and all relative two-nucleon partial waves with l ≦ 3 are retained. The optical potential is constructed by assuming a pure shell-model target and summing the state of the active nucleon through the single-particle states. The resulting non-locality is investigated explicitly and is found to be negligible. A coordinate space potential is constructed. When compared to the real parts of phenomenologically generated optical potentials, our potentials are found to be similar in the surface ( r ≈ 2.5 fm) but deeper in the interior. When our parameter-free real well is combined with phenomenological imaginary and spin-orbit wells, high-quality fits to the experimental data are obtained, comparable to those obtained when all three wells are chosen phenomenologically. Off-energy shell effects and the energy dependence are investigated.