Effective interaction for 16O(p,p') and 40Ca(p,p') at Ep=200 MeV

Differential cross sections and analyzing powers for scattering of 200 MeV protons have been measured for states of ¹⁶O up to 14.4 MeV and for states of ⁴⁰Ca up to 7.2 MeV of excitation. The data cover c.m. momentum transfers from approximately 0.4 fm^-1 to 3.0 fm^-1. Calculations were performed using several density-dependent effective interactions in the local density approximation. Empirical effective interactions from isoscalar normal-parity transitions were fitted to elastic and inelastic scattering data for ¹⁶O and ⁴⁰Ca either individually or simultaneously. Transition densities from electron scattering were used to minimize uncertainties due to nuclear structure. The fitted interactions were iterated to generate optical potentials self-consistently. We find that the empirical interaction, although strongly dependent on the local density, is essentially independent of target or state. We also find that the empirical interaction is reduced in strength at zero density. Finally, the results were compared with a relativistic impulse approximation model and with a recent global optical potential from Dirac phenomenology.