Inorganic scintillators are widely used for fast timing applications in high-energy physics (HEP) experiments, time-of-flight positron emission tomography and time tagging of soft and hard x-ray photons at advanced light sources. As the best coincidence time resolution (CTR) achievable is proportional to the square root of the scintillation decay time it is worth studying fast cross-luminescence, for example in BaF₂ which has an intrinsic yield of about 1400 photons/MeV. However, emission bands in BaF₂ are located in the deep-UV at 195 nm and 220 nm, which sets severe constraints on photodetector selection. Recent developments in dark matter and neutrinoless double beta decay searches have led to silicon photomultipliers (SiPMs) with photon detection efficiencies of 20%–25% at wavelengths of 200 nm. We tested state-of-the-art devices from Fondazione Bruno Kessler and measured a best CTR of 51 5 ps full width at half maximum when coupling 2 mm 2 mm 3 mm BaF₂ crystals excited by 511 keV electron–positron annihilation gammas. Using these vacuum ultraviolet SiPMs we recorded the scintillation kinetics of samples from Epic Crystal under 511 keV excitation, confirming a fast decay time of 855 ps with 12.2% relative light yield and 805 ns with 84.0% abundance, together with a smaller rise time of 4 ps beyond the resolution of our setup. The total intrinsic light yield was determined to be 8500 photons/MeV. We also revealed a faster component with 136 ps decay time and 3.7% light yield contribution, which is extremely interesting for the fastest timing applications. Timing characteristics and CTR results on BaF₂ samples from different producers and with different dopants (yttrium, cadmium and lanthanum) are given, and clearly show that the the slow 800 ns emission can be effectively suppressed. Such results ultimately pave the way for high-rate ultrafast timing applications in medical diagnosis, range monitoring in proton or heavy ion therapy and HEP.

无机闪烁体广泛用于高能物理 (HEP) 实验中的快速计时应用、飞行时间正电子发射断层扫描以及先进光源下软和硬 X 射线光子的时间标记。由于可实现的最佳符合时间分辨率 (CTR) 与闪烁衰减时间的平方根成正比，因此值得研究快速交叉发光，例如在 BaF ₂中，其固有产额约为 1400 光子/MeV。然而，BaF _{2中的发射带}位于 195 nm 和 220 nm 的深紫外区，这对光电探测器的选择设置了严格的限制。暗物质和无中微子双β衰变搜索的最新发展导致硅光电倍增管 (SiPM) 在 200 nm 波长下的光子检测效率为 20%–25%。我们测试了来自 Fondazione Bruno Kessler 的最先进的设备，并在耦合 2 mm 2 mm 3 mm BaF _{2时测量了 51 5 ps 全宽的最佳 CTR}由 511 keV 电子-正电子湮没伽马激发的晶体。使用这些真空紫外 SiPM，我们记录了 Epic Crystal 样品在 511 keV 激发下的闪烁动力学，证实了 855 ps 的快速衰减时间和 12.2% 的相对光产率和 805 ns 的 84.0% 丰度，以及更小的上升时间 4 ps超出了我们设置的分辨率。总的本征光产量被确定为 8500 光子/MeV。我们还展示了一个更快的组件，它具有 136 ps 的衰减时间和 3.7% 的光输出贡献，这对于最快的时序应用来说非常有趣。BaF _{2的时序特性和 CTR 结果}给出了来自不同生产商和不同掺杂剂（钇、镉和镧）的样品，并清楚地表明可以有效抑制缓慢的 800 ns 发射。这些结果最终为医疗诊断、质子或重离子治疗中的范围监测和 HEP 中的高速超快计时应用铺平了道路。