Ariño-Estrada Gerard, Roncali Emilie, Selfridge Aaron R, Du Junwei, Glodo Jaroslaw, Shah Kanai S, Cherry Simon R
Department of Biomedical Engineering, University of California at Davis, Davis, CA 95616 USA.
Biomedical Engineering Department, University of California, Davis, CA 95616 USA. He is now with United Imaging America, Houston, TX 77054, USA.
IEEE Trans Radiat Plasma Med Sci. 2021 Sep;5(5):630-637. doi: 10.1109/trpms.2020.3024032. Epub 2020 Sep 17.
Thallium bromide (TlBr) and thallium chloride (TlCl) are semiconductor materials with high transparency to visible light, high index of refraction, and high detection efficiency for gamma rays and annihilation photons. This manuscript reports on measurements of the light intensity and timing response of Čerenkov light emitted in one 3 mm × 3 mm × 5 mm slab of each of these materials operated in coincidence with a lutetium fine silicate (LFS) crystal with dimensions of 3 mm × 3 mm × 20 mm. A Na radioactive source was used. The measured average number of detected photons per event was 1.5 photons for TlBr and 2.8 photons for TlCl when these materials were coupled to a silicon photomultiplier. Simulation predicts these results with an overestimation of 12%. The best coincidence time resolution (CTR) for events in TlBr and TlCl were 329 ± 9 ps and 316 ± 9 ps, respectively, when events with 4 photons and >7 photons were selected. Simulation showed the CTR degraded from 120 ps to 405 ps in TlCl, and from 160 ps to 700 ps in TlBr when the first or second Čerenkov photon were selected. Results of this work show TlCl has a stronger Čerenkov light emission compared to TlBr and a greater potential to obtain the best timing measurements. Results also stress the importance of improving detection efficiency and transport of light to capture the first Čerenkov photon in timing measurements.
溴化铊（TlBr）和氯化铊（TlCl）是对可见光具有高透明度、高折射率以及对伽马射线和湮没光子具有高探测效率的半导体材料。本手稿报道了在与尺寸为3毫米×3毫米×20毫米的硅酸镥（LFS）晶体符合操作的情况下，对这两种材料各自的一个3毫米×3毫米×5毫米平板中发射的切伦科夫光的光强和时间响应的测量。使用了一个钠放射性源。当这些材料与硅光电倍增管耦合时，测得的每次事件探测到的光子平均数量，对于TlBr为1.5个光子，对于TlCl为2.8个光子。模拟预测这些结果时高估了12%。当选择有4个光子和>7个光子的事件时，TlBr和TlCl中事件的最佳符合时间分辨率（CTR）分别为329±9皮秒和316±9皮秒。模拟显示，当选择第一个或第二个切伦科夫光子时，TlCl中的CTR从120皮秒降至405皮秒，TlBr中的CTR从160皮秒降至700皮秒。这项工作的结果表明，与TlBr相比，TlCl具有更强的切伦科夫光发射，并且在获得最佳时间测量方面具有更大的潜力。结果还强调了在时间测量中提高探测效率和光传输以捕获第一个切伦科夫光子的重要性。
