Optimize neutron minimum detectable dose of OSL composite neutron detectors based on Al2O3:C and 6LiF

Abstract

The n/γ ratio and minimum detectable dose (MDD) are two crucial parameters in the measurement of neutrons in a mixed field comprising both neutrons and gamma rays. In this study, four OSL neutron detectors based on ⁶LiF and very sensitive α-Al₂O₃:C powder with grain sizes of less than 100 and 38 μm, respectively, were developed. The first use of the detector pair comprised single-crystal α-Al₂O₃:C detectors and neutron-sensitive OSL composite detectors represents a pioneering advancement in the field. The n/γ ratio and MDD at various integration times were first investigated. For the four neutron detectors, the neutron response of the neutron detectors with a mixture of 1:1 mass ratio of the α-Al₂O₃:C powder with grain sizes of less than 100 μm and ⁶LiF exposed to the D₂O moderated ²⁵²Cf source was the highest. When the integration time was 0.5 s, the MDD of the neutron detectors with a mixture of 1:1 mass ratio of the α-Al₂O₃:C powder with grain sizes of less than 100 μm and ⁶LiF was 6.1, 41.0, and 56.1 μSv, respectively, when irradiated by a calibrated D₂O moderated ²⁵²Cf source, a bare ²⁵²Cf source and a bare ²⁴¹Am–Be source. A comparison of the results indicates that the composite OSL neutron detectors based on Al₂O₃:C and ⁶LiF of this study have demonstrated a notable improvement in MDD.