Optimizing the design of a moderator-based neutron detector for a flat response curve in the 2-14 MeV energy range

The efficiency of a neutron detector with boron trifluoride proportional tubes embedded in a polyethylene moderator was simulated with a Monte Carlo program. A moderator structure where the detector had uniform sensitivity for neutrons from 2 to 14 MeV was determined by simulation. A counter was built based on the simulation results. The counter's efficiencies were calibrated with an Am-Be source and an accelerator that served as a D-D and D-T neutron source. Experimental neutron efficiencies of these sources are approximately uniform. The simulated model was validated by the consistent results between the calculated and experimental data.