Two-step contribution to intermediate energy (p, p ') and (p, n) reactions

We calculate the two-step contribution to (p,p ') and (p,n) reactions at in termediate energy. We describe the motion of the incident nucleon with a pl ane wave and compare the contribution from two-step processes with that fro m one-step processes. To describe the two-step processes, Re extend the res ponse functions to nondiagonal forms with respect to the momentum transfer q. We performed a numerical calculation for the cross sections of the C-12, Ca -40(p, p ') scattering and the spin longitudinal and spin transverse cross sections of the C-12, Ca-40(p,n) reactions at 346 MeV and 494 MeV. We found that the two-step contribution is appreciable in comparison with the one-s tep processes in the higher-energy transfer region for the spin longitudina l and the spin transverse (p, n) reactions. We also found that the two-step processes give larger contributions to the spin transverse (p, n) reaction than to the spin longitudinal reaction. This finding is very encouraging t o interpret the discrepancy between the DWIA calculation and the experiment al results of the spin longitudinal and the spin transverse cross sections.