Performance of real-time neutron/gamma discrimination methods

Abstract

Nuclear security usually requires the simultaneous detection of neutrons and gamma rays. With the development of crystalline materials in recent years, Cs2LiLaBr6 (CLLB) dual-readout detectors have attracted extensive attention from researchers, where real-time neutron/gamma pulse discrimination is the critical factor among detector performance parameters. This study investigated the discrimination performance of the charge comparison, amplitude comparison, time comparison, and pulse gradient methods and the effects of a Sallen–Key filter on their performance. Experimental results show that the figure of merit (FOM) of all four methods is improved by proper filtering. Among them, the charge comparison method exhibits excellent noise resistance; moreover, it is the most suitable method of real-time discrimination for CLLB detectors. However, its discrimination performance depends on the parameters $${t}_\text{s}$$ t s , $${t}_\text{m}$$ t m , and $${t}_\text{e}$$ t e . When $${t}_\text{s}$$ t s corresponds to the moment at which the pulse is at 10% of its peak value, $${t}_\text{e}$$ t e requires a delay of only 640–740 ns compared to $${t}_\text{s}$$ t s , at which time the potentially optimal FOM of the charge comparison method at 3.1–3.3 MeV is greater than 1.46. The FOM obtained using the $${t}_\text{m}$$ t m value calculated by a proposed maximized discrimination difference model (MDDM) and the potentially optimal FOM differ by less than 3.9%, indicating that the model can provide good guidance for parameter selection in the charge comparison method.