Cross sections and polarization observables for the40Ca(p,n)reaction at 345 MeV and multistep contributions in the continuum

Abstract

The double-differential cross sections and analyzing powers over an angular range of $30\ifmmode^\circ\else\textdegree\fi{}l~{\ensuremath{\theta}}_{\mathrm{lab}}l~75\ifmmode^\circ\else\textdegree\fi{},$ and the induced polarizations P and polarization transfer values ${D}_{\mathrm{NN}}$ at $30\ifmmode^\circ\else\textdegree\fi{}$ and $40\ifmmode^\circ\else\textdegree\fi{}$ for the ${}^{40}\mathrm{Ca}(p,n)$ reaction are measured at a bombarding energy of 345 MeV. The data are compared with theoretical calculations in a semiclassical distorted wave (SCDW) model employing through three- and two-step contributions for cross sections and polarization observables, respectively. At forward angles, the SCDW calculations reproduce the observed cross sections fairly well around the quasielastic peak. The one-step contribution is dominant at ${\ensuremath{\theta}}_{\mathrm{lab}}=30\ifmmode^\circ\else\textdegree\fi{},$ while the two- and three-step contributions become more important with increasing reaction angle. At backward angles the calculations underestimate the cross sections in the whole region, which indicates the significance of higher-step contributions. The ${D}_{\mathrm{NN}}$ values, which are sensitive to the effective nucleon-nucleon interaction in the nuclear medium, are close to those calculated with the G-matrix interaction parametrized by the Melbourne group.