Proton Induced Reactions of Thorium—Fission Yield Curves

Abstract

The fission yields of a number of nuclides produced in proton-induced fission of ${\mathrm{Th}}^{232}$ were determined at several proton energies in the range of 6.7 Mev to 21.1 Mev. At the same time, the relative cross sections of the ($p,n$) and ($p,3n$) reactions on ${\mathrm{Th}}^{232}$ were also determined. It was found that, although the fission reaction was predominant at proton energies greater than 8 Mev, competition from the ($p,xn$) type of reaction was considerable over all energies investigated.The trough in the fission yield curve becomes shallower with increasing proton energy and this change was quantitatively determined over the energy range investigated. A model is proposed to explain the change in shape of the fission yield curves.An approximate determination of the excitation function for the ($p,f$) reaction was made; the shape of the resulting curve was at least qualitatively in agreement with the excitation function predicted from existing theory.