Thickness-dependent neutron detection efficiency of LiF-Si-based active neutron detector for boron neutron capture therapy

A LiF-Si-based active neutron detector was developed for the measurement of real-time BNCT neutron beam. Thermal-neutron detection efficiencies were adjustable to the neutron beam intensities at various measurement locations by simply exchanging the LiF neutron converter, while minimizing sensitivity to photons. The neutron detection efficiency ranges from 8 × 10−7 to 8 × 10−4 cm2. The thermal-neutron detection efficiencies were experimentally obtained by placing the neutron detectors inside an education reactor. Experimental results were verified using a Monte Carlo simulation technique. The simulated thermal-neutron detection efficiencies were in good agreement with the experimental results within the range of experimental uncertainties. Discrepancies in both sets of results were due to an insufficient assessment of LiF density and flatness. Surface-density neutron detection efficiencies were proposed to more accurately measure neutron fluence rates.