Ranges and Kinetic Energies of Fragments from Fission ofU238Induced by 14.5-MeV Neutrons

The average ranges of eight fission-product recoils in uranium, including both symmetric and asymmetric fragments, have been measured radiochemically from 14.5-MeV-neutron-induced fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, using the thick-target technique. The measured average ranges, corrected for anisotropy, scattering, and edge effects, are, in mg/${\mathrm{cm}}^2$ U: ${}_{}{}^{91}{}_{}{}^{}\mathrm{Sr}$: 10.21±0.42, ${}_{}{}^{99}{}_{}{}^{}\mathrm{Mo}$: 11.20±0.29, ${}_{}{}^{113}{}_{}{}^{}\mathrm{Ag}$: 9.63±0.33, ${}_{}{}^{115}{}_{}{}^{}\mathrm{Cd}$: 9.90±0.97, ${}_{}{}^{117}{}_{}{}^{}\mathrm{Cd}$: 9.36±0.45, ${}_{}{}^{121}{}_{}{}^{}\mathrm{Sn}$: 9.47±0.87, ${}_{}{}^{139}{}_{}{}^{}\mathrm{Ba}$: 7.60±0.14, and ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ba}$: 8.14±0.28. Using Niday's range-velocity relation, these ranges were converted to kinetic energies of the fragments to determine if there exists a deficit in total kinetic energy release at symmetric mass division. A dip was observed in the range-versus-mass curve, but the magnitude of this dip was smaller than what was previously reported in thermal-neutron fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. The maximum total kinetic energy release at mass ratio 1.36 was found to be 176.7±3.3 MeV, and the deficit in the energy release, corresponding to the observed dip in the range-mass curve, at symmetric fission was estimated to be 17±5 MeV.