We have performed optical-model calculations using the Klein-Gordon and the Dirac equations for the 600 MeV $p-{}_{}{}^4{}_{}{}^{}\mathrm{He}$ scattering experiments of Boschitz et al., and the 1050 MeV $p-{}_{}{}^4{}_{}{}^{}\mathrm{He}$ scattering experiments of Baker et al. We have compared these analyses with our previous analysis of the 1000 MeV $p-{}_{}{}^4{}_{}{}^{}\mathrm{He}$ 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 ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ matter radius obtained from electron scattering, and substantially smaller than the low energy ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ optical potential rms radius. On the other hand, the experiments require quite different values for the optical potential strength parameters.

NUCLEAR REACTIONS ${}_{}{}^4{}_{}{}^{}\mathrm{He}(p,p)E=600, 1000, 1050$ MeV, $\sigma \left(\theta \right)$ calculated, deduced optical-model parameters.

• Received 28 July 1975

DOI:https://doi.org/10.1103/PhysRevC.14.1878