Developing a Forward Model of Single-hit Array Detector for Reaction-In-Flight Neutrons Measurement

In deuterium-tritium (DT) nuclear fusion, primary reactions produce 14.1 MeV mono-energetic neutrons. A small fraction of DT fuel ions undergo a knock-on process by the 14.1 MeV neutrons, which results in the production of high energy neutrons with energy up to 30 MeV (i.e., reaction-in-flight (RIF) or tertiary neutrons). It is beneficial to observe and analyze RIF neutrons as they include useful information such as fuel areal density and mix, however, measuring the shape of RIF neutron energy spectrum is challenging due to its small production yield compared to primary DT yield (10^-4 – 10^-8). In the past, single-hit neutron arrays have demonstrated the ability to measure a small quantity of DT neutron spectral information during deuterium-deuterium fusion. A similar forward model has been developed to determine if the single-hit array approach can be applicable in measuring the energy distribution of the RIF neutrons in inertial-confinement-fusion.