The total kinetic energy (TKE) in the fast neutron induced fission of 237Np was measured for neutron energies from En = 2.6 – 45.7 MeV at the LANSCE- WNR facility. The postTKE release decreases non-linearly with increasing incident neutron energy and can be represented as TKE(MeV) = (169.365 ± 1.551) + (6.846 ± 3.337) log10En - (6.235 ± 1.623)(log10En)2 for En > 1 MeV. Analysis of the fragment mass distributions indicates that the decrease in TKE with increasing En is a consequence of two factors; shell effects fade out at high excitation energies, resulting in the increasing occurrences of symmetric fission, and TKEasym decreases rapidly at high En.
Funding Statement (additional comments about funding)
This material is based upon work supported in part by the U.S. Department of En- ergy, Office of Science, Office of Nuclear Physics under award number DE-FG-06- 97ER41026 (OSU) and under contract 89233218CNA000001 (LANL). University collaborators acknowledge support from this work from the DOE NNSA Steward- ship Science Academic Alliances Program under Grant No. DE-NA0003907. This research benefited from the use of the LANSCE accelerator facility. Nuclides used in this research were supplied by the United States Department of Energy Office of Science by the Isotope Program in the Office of Nuclear Physics.