Optical-model partial-wave analyses of p-4He elastic scattering

We have performed optical-model calculations using the Klein-Gordon and the Dirac equations for the 600 MeV p-4He scattering experiments of Boschitz et al., and the 1050 MeV p-4He scattering experiments of Baker et al. We have compared these analyses with our previous analysis of the 1000 MeV p-4He experiment of Palevsky et al. In comparing the results at the three energies we find that the experiments require a slightly energy-dependent optical potential rms radius. The average value is in good agreement with the 4He matter radius obtained from electron scattering, and substantially smaller than the low energy 4He optical potential rms radius. On the other hand, the experiments require quite different values for the optical potential strength parameters