Monte Carlo Calculations of Nuclear Evaporation Processes. IV. Spectra of Neutrons and Charged Particles from Nuclear Reactions

Abstract

The calculation of spectra of neutrons and charged particles and of cross sections for their production from nuclear reactions is compared with experimental values. A compound-nucleus mechanism followed by nuclear evaporation is assumed for the reactions Zr, Ta, $\mathrm{B}\mathrm{i}(14.1-\mathrm{M}\mathrm{e}\mathrm{v} n, n^{\prime })$; $\mathrm{N}\mathrm{i}(13.4-17.5-\mathrm{M}\mathrm{e}\mathrm{v} n, p)$; Cu, $\mathrm{P}\mathrm{d}(23-\mathrm{M}\mathrm{e}\mathrm{v} p, \alpha )$; and $\mathrm{N}\mathrm{i}(162-\mathrm{M}\mathrm{e}\mathrm{v} {\mathrm{O}}^{16}, \alpha )$. The production of neutrons and charged particles from the interaction of 190-Mev protons with Ni, Ag, and Au is analyzed in terms of a nucleon cascade, followed by particle evaporation. The calculation of the nuclear evaporation is based on Weisskopf's statistical theory. Fairly good agreement is obtained for the values of the cross sections for producing these particles with an appropriate set of radius and level-density parameters in each case. There are serious discrepancies, however, in the comparison of the experimental and calculated spectra; many of the latter are deficient in low-energy neutrons and charged particles. Possible improvements in the calculation are discussed.