Calculation Of Mass Yield Distributions In Fission Induced By High Energy Protons

Abstract

An analytical expression is obtained for the mass-yield distribution in fission induced by high-energy protons, using a two-step model. In the first step, the incident proton penetrates the target nucleus, knocking out some of its constituting nucleons and leaving a residual nucleus in an excited state. In the second step, the residual nucleus fissions. The mass-yield distribution in the fission of this residual nucleus is described within the hypothesis of two independent fission modes, with parameters extracted from the analysis of low-energy fission. Comparison with experimental data of the mass yield in fission of "'U induced by 190 MeV protons shows that the agreement with experiment can be achieved only if one assumes that a considerable amount of excitation energy is removed from the residual nucleus by nucleon evaporation prior to fission