2021/11/25 by Connolly, D., Montoya, K. B., Duke, D. L. +7
#FOS: Physical sciences #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2111.12895
Neutron-induced fission of 237Np has been measured over a wide range of incident neutron energies using a twin Frisch-gridded ionization chamber (TFGIC) and a thin-backed 237Np target. These measurements were performed at the Los Alamos Neutron Science Center - Weapons Neutron Research (LANSCE - WNR) facility, which provides a collimated beam of neutrons with energies ranging from 100s of keV to 100s of MeV. The data were analyzed using the double-energy (2E) method, with mass-dependent corrections for prompt-fission neutrons and pulse height defect. Pre- and post-neutron evaporation average total kinetic energy (⟨ TKE⟩) values are reported for 54 incident neutron energies in the energy range 0.20 ≤ En ≤ 100.0 MeV and compared to existing data and evaluations. Pre- and post-neutron evaporation mass yields were extracted with a full width at half maximum (FWHM) resolution of 4u and compared to existing data and evaluations. The present ⟨ TKE⟩ and mass yield data agree with previous results and also with statistical models of 237Np(n,f) at incident neutron energies between En = 0.2 - 20.0 MeV. A flattening of the ⟨ TKE⟩ data is observed (relative to the prediction of the GEF model) above En = 20.0 MeV. However, the interpretation of this discrepancy is unclear as the analysis method's neglect of incomplete momentum transfer at high energies, as well as pre-equilibrium pre-fission phenomena likely have a significant impact on the measurement at such high incident neutron energies.