Effects of finite range and exchange interaction in (p, n) and (n, p) knockout reactions

Abstract

Angular distributions based on the distorted-wave Born approximation taking into account the effects of finite range and exchange interaction have been calculated for four (p, n) and one (n, p) knockout reaction for target nuclei with atomic mass numbers between 13 and 91, for bombarding energies from 5.3 to 20 MeV and for a wide range of bound state orbital angular momenta. Finite range is treated both exactly and approximately, using various approximations and the results are compared with each other. An admixture of Wigner, Majorana, Bartlett and Heisenberg interactions with a Yukawa potential form factor is assumed for the neutron-proton interaction. The Woods-Saxon potential is used to evaluate the bound state wave functions. Experimental comparisons have been made for the 13C(p, n) 13N and 28Si(n, p) 28Al ground state reactions. Neither the zero-range approximation, nor any of the other approximations considered yield results which quantitatively are consistently reliable. Many of the cross sections exhibit a great sensitivity to exchange mixtures at certain angles, as well as to the bound state wave functions and it may be possible in future investigations to take advantage of this property to determine nuclear parameters.