Proton-nucleus total cross sections in the intermediate energy range

Proton-nucleus total and reaction cross sections are computed for a number of target nuclei at energies ranging from 100 to 2200 MeV using the Kerman, McManus, and Thaler optical potential formalism and the impulse approximation. Corrections due to Pauli, short-range dynamical, and center-of-mass correlations are included in the calculations. In addition, the electric form factor of the neutron and the nucleon magnetic moments are included in deriving the necessary proton densities from available empirical charge distributions. The proton-nucleon scattering amplitudes are obtained from phase shift solutions or directly from the published $N-N$ data. The proton and neutron point densities are deduced where possible from analyses of electron and proton scattering or from Hartree-Fock predictions if the appropriate elastic angular distribution data are unavailable. An estimate of the uncertainty in the calculated total cross sections is given. The total and reaction cross sections computed in this way are shown to be in very good agreement with the data above 400 MeV but overestimate the data by 15-25% at lower energies, indicating that the approximate multiple scattering calculations generally performed near 1 GeV are inadequate when applied at energies below 400 MeV. Several theoretical improvements are suggested for this lower energy range and some numerical estimates are given. Analysis of total cross section data is also shown to be an unsuitable method for obtaining accurate measurements of neutron matter densities.