Abstract: Barium fluoride (BaF₂) crystal is known as the fastest scintillation crystal, which has a wide application prospect in high energy physics, nuclear physics and nuclear medicine. It is very important to suppress the slow luminescence component of BaF₂ crystal for its engineering application. BaF₂ crystals with high Y³⁺ doping concentration 5%, 8%, 10% (mole fraction) were prepared by Bridgman method, and the co-doped BaF₂ fast response scintillation crystals were prepared by co-doping Y³⁺ with alkali metal ions (Li⁺, Na⁺) to form charge compensation to eliminate the generation of interstitial F^-. Then, based on the optimized 5 ns and 2 500 ns time gate width measurement methods, the effects of Y³⁺ doping concentration and the co-doping concentration of Y³⁺ and alkali metal ions (Li⁺, Na⁺) on the fast/slow component ratio of BaF₂ scintillation crystal were studied. The results show that the optical quality of the high concentration Y³⁺ doped BaF₂ crystals is excellent, and the transmittance at 220 nm and 300 nm is higher than 90% and 92%, respectively. With the increase of Y³⁺ doping concentration from 0 to 10%, the slow luminescence component of BaF₂ crystal decrease significantly, and the fast/slow component ratio increase from 0.15 to 1.21. The slow luminescence component of the grown Y³⁺/Li⁺ and Y³⁺/Na⁺ co-doped BaF₂ crystals are further decrease compared with that of the Y³⁺ doped BaF₂ crystals, and the highest fast/slow component ratios obtained are 1.63 and 1.61, respectively. The co-doped BaF₂ fast response scintillation crystal is expected to be applied in the frontier experiments of high energy physics and nuclear physics.

Key words: barium fluoride, scintillation crystal, co-doping, fast/slow component ratio, fast time response, Bridgman method