Analysis Of The (P, Alpha) Reaction Using The Preequilibrium Multistep Direct Feshbach-Kerman-Koonin Theory

The Feshbach-Kerman-Koonin theory of multi-step pre-equilibrium reactions has been used to analyse the (p, alpha) reaction at incident energies of 30 and 44.3 MeV on several nuclei. It is assumed that the reaction takes place by the direct knockout of a preformed alpha particle bound in a shell-model state of the core. Zero-range Gaussian and Yukawa forms are used for the proton-alpha interaction and several parameter sets for the proton and alpha-particle optical potentials. The theory is able to fit the data at the higher emission energies, and most of the remaining cross section is attributable to compound nucleus emission. There is little evidence for multi-step compound emission.