Shi Hongsheng

Growth and properties of Gd:NBW crystal

Gd:NBW crystals are grown by modified Bridgman method for the first time. The Gd segregation coefficient is calculated. Photoluminescence and the light yield of the Gd:NBW crystal are measured. The main elements and the impure ions in the NBW crystal are respectively analyzed by EPMA and GDMS. All these results show that the Gd:NBW crystal is a promising scintillator material.

Radiation Induced Optical Absorption of Cubic Lead Fluoride Crystals and the Effect of Annealing

Transparent and colorless lead fluoride crystals with sizes of 20 × 20 × 20 (mm3) are irradiated with several doses of γ-rays from a 60 Co source. Their transmittance spectra before and after irradiation are measured, and a new parameter ΔT = Tb − Ta is defined to evaluate the irradiation damage. Three optical absorption bands peaking at 270 nm, 370 nm and 500 nm are found in the plots of ΔT versus wavelength, and their intensities increase with the irradiation dose. These optical absorption bands, except the one at 270 nm, can recover spontaneously with time. Thermal annealing treatment can enhance this recovery of the transmittance, while the optimum annealing temperature for different samples depends on the irradiation dose.