Effects of Yttrium Doping (0–20 at%) on the Scintillation Performance of BaF 2 Crystals

Barium fluoride (BaF2) crystal is an ultrafast scintillator known for a sub-nanosecond fast component. Recent studies have shown that yttrium (Y) doping effectively suppresses the slow scintillation component. In this study, we comprehensively investigate the impact of Y doping by growing BaF₂ crystals with nominal Y concentrations in the range of 0 to 20 at%. The actual Y concentration in BaF₂:Y crystal samples was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the optical transmittance (OT), radioluminescence (RL), fast/slow component ratio (F/S) of light output (LO), energy resolution (ER), and decay time (DT) were systematically measured. It was found that Y doping influences not only the LO and F/S but also the DT of BaF₂ crystals. As the doping concentration increased from 0% to 20 at%, the LO intensity of the slow component decreased to 6% of that of undoped crystal, while that of the fast component reduced to 60% of undoped crystal. Consequently, the F/S increased from 0.13 to 1.36, whereas ER@511keV degraded from 12.1% to 38.7%. The LOs of slow and fast components showed distinct trends: the slow component decreased rapidly below 1 at% Y and then decayed with an offset-exponential trend, while the fast component remained up to 2 at% before declining linearly. The slow component in Y-doped BaF₂ crystals consists of two distinct decay processes: the slower one that decreases from 755 ns to 381 ns, and the faster one that declines from 199 ns to 41 ns upon doping with Y.