Approach for calculating multistep direct reactions of continuum and discrete levels.

Abstract

A method for calculating multistep direct reactions for both continuum and discrete levels is proposed. The energy-angle correlation scattering kernel is adopted for continuum and discrete levels in the semiclassical approach, in which the angular momentum and parity conservations are considered. Then, following the Feshbach, Kerman, and Koonin quantum multistep direct reactions theory, the Legendre coefficients of the angular distributions are calculated based on one-step distorted-wave Born approximation instead of nucleon-nucleon scattering expressions in nuclear matter. Since the quantum effects are properly considered, we call it the quasiquantum multistep direct reactions theory. For the specific reaction considered here, the calculated discrete level neutron angular distributions of the $^{11}\mathrm{B}$(p,${\mathit{n}}_{0}$${)}^{11}$C reaction and the cross sections of the $^{11}\mathrm{B}$(p,${\mathit{n}}_{0}$${)}^{11}$C and the $^{11}\mathrm{B}$(p,n${)}^{11}$C reactions reproduce the experimental data reasonably. This approach can also be used to composite particle emissions.