Nuclear Effects in the Production ofπ+andπ−by Protons on Nuclei

We have modified an earlier semiclassical model of pion production by protons on nuclei by including various nuclear physics corrections. In addition to allowing for $pn$ charge exchange and realistic nuclear densities, we have corrected the two-body input cross sections for the effects of the Pauli principle, Fermi motion, and nuclear optical potentials. The agreement with experiment is similar to that obtained earlier. Ambiguities arising from the nuclear corrections are found to be larger than the effects of moderate variations of the nuclear surface parameters.