Silver-Doped LiI Crystal: A Sensitive Thermal Neutron Detector With Pulse Shape Discrimination

Single crystals of LiI with different Ag concentrations are investigated for dual-mode thermal neutron and γ-ray detection. The crystal growth and scintillation properties of these crystals have been studied and reported in our recent communication. On the other hand, a LiI crystal with Eu
²⁺
dopant was used for thermal neutron detection using pulse height discrimination (PHD). However, the LiI:Eu crystal has a disadvantage in the case of high-energetic gamma background which is usually accompanied with neutrons in practical applications. In this case, LiI:Ag might be a better option since it can distinguish neutrons and γ-signals by both pulse shape discrimination (PSD) and PHD. The PSD capability of LiI:Ag was checked for alpha and gamma signals. The figure-of-merit (FOM) value was estimated to be 1.7 using the charge comparison method. LiI:Ag crystals were encapsulated for neutron measurements using
²⁵²
Cf and Am-Be sources. The best FOM value was obtained to be 1.5 for the LiI:0.1%Ag crystal. The current investigation reveals that LiI:Ag can be a promising candidate for the dual-mode thermal neutron and γ-ray spectroscopy applications.