Research on angle sensitivity of the boron-lined multilayer converter neutron detector

Abstract

Abstract In our previous work, a new design for a gaseous neutron detector composed of a boron-lined multilayer converter was proposed to replace the 3He proportional counter, and a prototype detector was constructed to test its performance and characteristics. The neutron detection efficiency varies for different incident angles of neutrons to the converter surface, mainly due to the effective area of the converter and the emitting probability of the alpha and 7Li. Hence, the variation of detection efficiency with the incident angle is analyzed theoretically in this work, and then the GEANT4 simulations and preliminary experimental tests are conducted to verify the calculation results. The highest detection efficiency is obtained at 1.72° (100 mm length, 3 mm gap, and θ = atan (3/100) ≈ 1.72°), the detection efficiency decreases sharply when the angle approaches 0°, and the detection efficiency decreases gradually when the incident angle is larger than 1.72°. The simulation results and experimental results are consistent with the trend of theoretical calculation. Therefore, the proposed detector is suitable for angle-sensitive applications, such as small angle neutron scattering and locating the isotopic neutron sources.