Potential of Cerenkov Radiation for Fast Timing of TlBr Semiconductor Detectors for PET

摘要 将直接半导体检测用于正电子发射断层扫描(PET)的一个关键限制是 电荷载流子的漂移时间相对较慢，这导致较差的符合定时。我们建议 切伦科夫光可以用作半导体中的快速定时信号，例如TlBr.切伦科夫光发射出来 当伽马射线产生光电子并有可能提供信号时，准瞬时 具有飞行时间精度，即使对于半导体探测器也是如此。切伦科夫成像只是提出了一种 几年前，作为一种新的方式和第一个实验结果切伦科夫光探测的BGO 最近发表的，显示符合时间分辨率为270 ps。切伦科夫光在TlBR中将更多 由于其较高的折射率，其强度比BGO强。切伦科夫光作为快速定时信号的应用 在半导体探测器中的应用尚未见报道。就以下方面而言，TlBr是PET的最佳检测器 然而，在效率和能量分辨率方面，其定时响应会影响其整体性能。使用 切伦科夫光作为一种快速信号，可以为TlBR提供飞行时间计时性能，并将其转换为 最完整的PET探测器之一。 该方案的目的是演示和表征TlBr中切伦科夫光的探测。这个 具体目标是了解TlBR中切伦科夫光的产生和传输，以及 使用耦合到光电探测器的TlBr板来检测这种光。本项目的三个具体目标是1) TlBR中可见光透过率的测量，2)TlBR中切伦科夫光产生的模拟， 3)T1BR中切伦科夫光的探测和时间分辨率的测量。这个 实验测量将用于验证模拟并获得能够预测的工具包 可靠地由TlBr板发出的切伦科夫光取决于它的尺寸并将其外推到另一个 半导体材料。 这些具体目标将足以证明使用切伦科夫光作为T1BR和T1BR的快速信号的可行性 为半导体探测器团体提供一个模拟工具包，以促进TlBr的生产 探测器经过优化，可探测切伦科夫光。

ABSTRACT A key limitation for using direct semiconductor detection for positron emission tomography (PET) is the relatively slow drift times of the charge carriers which leads to poor coincidence timing. We propose that Cerenkov light can be used as a fast timing signal in semiconductors such as TlBr. Cerenkov light is emitted quasi-instantaneously when a gamma-ray generates a photoelectron and has the potential to provide a signal with a time-of-flight precision even for semiconductor detectors. Cerenkov imaging has been proposed just a few years ago as a new modality and the first experimental results of Cerenkov light detection with BGO have been published recently, showing a coincidence time resolution of 270 ps. Cerenkov light in TlBr will be more intense than in BGO due to its higher index of refraction. The utilization of Cerenkov light as a fast timing signal in semiconductor detectors has not been reported yet. TlBr is an optimum detector for PET in terms of efficiency and energy resolution, however, its timing response compromises its overall performance. Using the Cerenkov light as a fast signal could provide TlBr with a time-of-flight timing performance and convert it into one of the most complete detectors for PET. The goal of this proposal is to demonstrate and characterize the detection of Cerenkov light in TlBr. The specific aims address understanding of the generation and transmission of Cerenkov light in TlBr, and the detection of this light using TlBr slabs coupled to photodetectors. The three specific aims of this project are 1) the measurement of visible light transmittance in TlBr, 2) the simulation of Cerenkov light generation in TlBr, and 3) the detection of Cerenkov light generated in TlBr and measurement of timing resolution. The experimental measurements will be used to validate the simulation and to obtain a toolkit able to predict reliably the Cerenkov light emitted by a TlBr slab depending on its dimensions and to extrapolate it to other semiconductor materials. These specific aims will be sufficient to prove the feasibility of using Cerenkov light as a fast signal in TlBr and to provide the semiconductor detector community with a simulation toolkit that facilitates the production of TlBr detectors optimized to detect Cerenkov light.