Fission-fragment properties in U238(n,f) between 1 and 30 MeV

Abstract

The fragment mass and kinetic energy in neutron-induced fission of $^{238}\mathrm{U}$ has been measured for incident energies from 1 to 30 MeV at the Los Alamos Neutron Science Center. The change in mass distributions over this energy range were studied, and the transition from highly asymmetric to more symmetric mass distributions is observed. A decrease in average total kinetic energy $(\overline{\mathrm{TKE}})$ with increasing excitation energy is observed, consistent with previous experimental work. Additional structure at multichance fission thresholds is present in the $\overline{\mathrm{TKE}}$ data. The correlations between fragment masses and total kinetic energy and how that changes with excitation energy of the fissioning compound nucleus were also measured. The fission mass yields and average total kinetic energy are important for fission-based technologies such as nuclear reactors to understand nuclear waste generation and energy output when developing new and advanced concepts. The correlations between fragment mass and kinetic energy are needed both as input for theoretical calculations of the deexcitation process in fission fragments by prompt radiation emission and for validating advanced theoretical fission models describing the formation of the primordial fragments.