Atomistic modeling to the investigation of irradiation effect on optical properties of LiI/ZnS scintillator in a research reactor-based neutron radiography facility

Abstract

Scintillation material presents a variety of applications used in radiation environments such as dosimetry, spectrometry, and radiography facility. Neutron radiography is a non-destructive testing (NDT) method that uses a proper scintillator such as LiI/ZnS for neutron detection. This paper investigated the effect of neutron-induced point defects on the optical properties of this scintillator used in TRR’s neutron radiography system. The combination of Monte Carlo and atomistic modeling methods was utilized in this regard. The results showed that the induced point defects lead to a more than 10 and 22% reduction in the refractive index and reflectivity of the LiI scintillator at optical wavelength respectively. Moreover, the refractive index of the ZnS scintillator decreases more than 6.4 % by Zn interstitial, Zn vacancy, and S vacancy and increases 8.9 % by S interstitial at optical wavelength.