Speaker
Description
Barium fluoride (BaF2) is a classic ultrafast scintillator with a sub-nanosecond fast component. Following our group's demonstration that yttrium (Y) doping effectively suppresses its intrinsic slow component, systematic investigations of the concentration-dependent scintillation performance and radiation tolerance are needed to guide its application in high-energy physics detectors. Here, BaF2 crystals with nominal Y concentrations of 0–20 at.% were systematically characterized in terms of optical transmittance, radioluminescence, light output (LO), fast-to-slow component ratio (F/S), energy resolution, and decay kinetics. Radiation damage was assessed after γ-ray irradiation at cumulative doses of 10 krad–10 Mrad. A 200-mm-long BaF2:Y crystal with a nominal Y concentration of 10 at.%, obtained via vertical Bridgman growth, was also characterized to evaluate its optical and scintillation properties and light-response uniformity.
The results reveal distinct concentration-dependent behaviors of the fast and slow components. At 20 at.% Y, the fast- and slow-component LOs decreased to 60% and 6% of those of undoped BaF2, respectively, increasing the F/S ratio from 0.13 to 1.36, while the energy resolution at 511 keV deteriorated from 12.1% to 38.7%. The two decay times of the slow component shortened from 755 to 381 ns and from 199 to 41 ns with increasing Y concentration. The 200-mm-long, 10 at.% Y-doped crystal exhibited good optical transmittance and light-response uniformity, with its slow-component intensity suppressed by approximately one order of magnitude relative to undoped BaF2. The effective Y segregation coefficient was 0.84. Regarding radiation damage, crystals containing 1–7.5 at.% Y exhibited lower emission-weighted radiation-induced absorption coefficients (EWRIACs) and relative LO losses than undoped BaF2, with the best radiation resistance at 2 at.% Y. At 10 Mrad, the EWRIACs for the fast and slow components were 4.6 and 4.0 m-1, respectively, with a relative LO loss of approximately 29%. In contrast, 10–20 at.% Y increased both radiation-induced absorption and LO loss. Phosphorescence spectra further revealed a Y-dependent redshift of broadband emission and an increasing contribution from narrowband emission. These findings provide guidance for selecting an appropriate Y doping concentration in BaF2 crystals for ultrafast radiation detection.
