Excitation energy deposition and the fission process in the reactions 63Cu + 92,100Mo at 10,17,25 and 35 AMeV 35 and 20Ne + 144,148,154Sm at 20 AMeV

Abstract

Excitation energy deposition and light particle emission for fissioning nuclei with excitation energies from 2 to 6 MeV/nucleon are studied for the reaction of 20 AMeV 20Ne with [144,148,154]Sm and 10, 17, 25 and 35 AMeV 63Cu with [92,100]Mo using the Texas A&M Neutron Ball detector. Linear momentum transfers (LMT) are determined from fission fragment folding angle measurements and used to estimate excitation energies. The associated multiplicities of neutrons, protons and a particles are obtained, together with their average energies. These data axe used to reconstruct the initial excitation energies of the compound nucleus. With increasing beam energy, an increasing discrepancy between the excitation energy derived from the LMT measurements and the reconstructed one is observed and attributed to intermediate mass fragment (IMF) emission. The measured neutron multiplicities show a strong increase with increasing neutron to proton ratio of the composite system, as well as increasing beam energy. The experimental data for light particle multiplicities are compared with calculations using the statistical model GEMINI. The effect of the dynamic fission delay on the light particle multiplicities is explored. The neutron multiplicities are relatively insensitive to the dynamic fission delay. The calculated charged particle multiplicities are more sensitive, but the comparisons between the calculation and experiment indicate that the light charged particle multiplicity data are not a good measure of dynamic fission delay.