Light charged particle and intermediate mass fragment emission in the reaction 640 MeVKr86+63Cu

Abstract

Light charged particles from the reaction 640 MeV ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$ ${+}^{63}$Cu have been measured in singles and in coincidence with intermediate mass fragments, fissionlike fragments, and other light charged particles. Multiplicities for ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in association with the evaporation residues, fragments, and intermediate mass fragments have been determined. Composite nuclei, most of which decay to evaporation residues, are the major sources of evaporative light-charged particle emission. Average multiplicities for prescission ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ can be associated with the composite nucleus en route to scission; they are relatively large and thus suggest a time scale for fission longer than that for evaporation. The multiplicities for ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in association with the intermediate mass fragments indicate that these fragments are usually born with a significant quantity of excitation energy. These multiplicities are used to estimate the primary masses and kinetic energies of the intermediate mass fragments.