Multistep Direct Reactions: A Microscopic Two-Component Approach

We present a multistep direct reaction theory for analyzing nucleon-induced reactions to the continuum for incident energies up to 200 MeV. Two principal advances in multistep direct theory are studied: (1) A microscopical approach for calculating DWBA transitions to the continuum, where transitions to all accessible 1p1h shell model states are explicity determined; (2) A two-component formulation of multistep direct reactions is given, where neutron and proton excitations are explicitly accounted for in the evolution of the reaction, for all orders of scattering. The multistep direct theory is applied, along with theories for multistep compound, compound, and collective reactions, to analyze experimental emission spectra for a range of targets and energies. The sensitivity to the employed optical model is demonstrated. We show that the theory correctly accounts for measured neutron and proton emission angle-integrated spectra, as well as angular distributions. Additionally, we note that these microscopic and two-component developments facilitate more fundamental studies into e ective nucleon-nucleon interactions in multistep calculations. A more complete exposition of this work can be found in Ref. [1].