Semiclassical distorted wave model analysis of multistep direct(p,p′x)and(p,nx)reactions to the continuum

Abstract

The semiclassical distorted wave (SCDW) model is extended to include three-step process in multistep direct (MSD) processes in nucleon-induced preequilibrium nucleon-emission reactions. The extended SCDW model is applied to analyses of MSD processes in ${}^{58}\mathrm{Ni}{(p,p}^{\ensuremath{'}}{x),}^{90}\mathrm{Zr}{(p,p}^{\ensuremath{'}}{x),}^{90}\mathrm{Zr}(p,nx),$ and ${}^{209}\mathrm{Bi}{(p,p}^{\ensuremath{'}}x)$ in the incident energy range of 62--160 MeV. SCDW calculations with no adjustable parameter give overall good agreement with experimental double differential cross sections, except at very small and large angles. The nonlocality of distorting potentials is taken into account in terms of the Perey factor, and is found to be essential for reproducing the absolute magnitude of the cross sections. Effects of the density and momentum distributions of target nucleons and the use of in-medium $N\ensuremath{-}N$ cross sections on the SCDW calculation are discussed. Comparison with other models is made, in particular regarding the contributions of individual multistep processes to the calculated cross sections. Validity of the local semiclassical approximation to distorted waves, which is essential to SCDW is discussed on the basis of a numerical test.