LOCAL REPRESENTATION OF THE EXCHANGE NONLOCALITY IN N-O-16 SCATTERING

The nonlocal Schrodinger equation is solved rigorously in a microscopi c folding model, incorporating both direct and knock-on exchange poten tials, for n-O-16 scattering at laboratory energies of 20 and 50 MeV. The model uses the complex and density dependent n-n interaction of N. Yamaguchi et al., uses harmonic oscillator wave functions for the bou nd nucleons, and calculates the scattering wave function for this nonl ocal problem using a Bessel-Sturmian expansion method incorporating co rrect boundary conditions. All spins are neglected. The local phase-eq uivalent potential is obtained from the scattering matrix elements at a given energy by using the iterative perturbative inversion method. T his representation allows comparison between the microscopic model and a phenomenological potential, showing good agreement for the local re al part of the potential at 20 MeV. From the ratio of the wave functio ns for the nonlocal potential and for the potential calculated by inve rsion, a Perey damping factor (PDF) is obtained which is of similar fo rm to the well-known Perey-Buck prescription for the PDF for a Gaussia n nonlocality of the conventional range of 0.85 fm. The significance o f these results for distorted wave Born approximation calculations is discussed.