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 atintermediate energy. We describe the motion of the incident nucleon with planewave and compare the contribution from the two-step processes with that fromthe one-step processes. To describe the two-step processes, we extende theresponse functions into the nondiagonal ones with respect to the momentumtransfer q. We performed a numerical calculation for the cross sections of the $^{12}$C,$^{40}$Ca(p,p') scatterings and the spin longitudinal and the spin transversecross sections of the $^{12}$C,$^{40}$Ca(p,n) reactions at 346 MeV and 494 MeV.We found that the two-step contribution is appreciable in comparison with theone-step processes in higher energy transfer region for the spin longitudinaland the spin transverse (p,n) reactions. We also found that the two-stepprocesses give larger contribution to the spin transverse (p,n) reaction thanto the spin longitudinal reaction. This finding is very encouraging tointerpret the discrepancy between the DWIA calculation and the experimentalresults of the spin longitudinal and the spin transverse cross sections.Comment: LaTeX, 18 pages, 11 Postscript file