闪烁探测器中高探测效率的硅光电倍增器的研究

Silicon photomultiplier (SiPM), a new type of solid state photon detector developed in recent years, has wide applications in the field of radiation detection. The major problem existing now is high photon detection efficiency (PDE) and large dynamic range of the SiPM cannot be obtained simultaneously, the SiPMs with quenching resistors integrated into bulk epitaxial silicon have been investigated, which are able to alleviate the conflict. The luminescence peak of some new scintillators such as LYSO is at about 420 nm, but SiPM with bulk quenching resistor has a low PDE in the wavelength range, that affects the performances of the scintillation detector. On the basis of SiPM with bulk quenching resistor, the design of P-on-N structure and shallow junction are to be studied in this project in order to realize the peak wavelength blue shifted and the PDE increased near 420 nm. Also, a model which allows one to calculate the PDE of SiPM as a function of junction depth and wavelength is to be established. Moreover, radiation detection sensitivity and energy resolution of 1-to-1 coupling of SiPM and lutetium yttrium oxyorthosilicate (LYSO) crystal will be tested to prove the feasibility of this SiPM as scintillation detector readout. This project has vital significance on the development of low-cost portable scintillation detector and in the field of radiation detection.

硅光电倍增器（SiPM）是近年来发展的一种新型固态光探测器，在核辐射探测领域具有广阔的应用前景。SiPM存在高探测效率和大动态范围不可兼得的矛盾，体电阻淬灭SiPM利用Si衬底材料的体电阻作为雪崩淬灭电阻，在很大程度上缓解该矛盾。LYSO等新型闪烁体的发光峰在420 nm左右，目前研制出的体电阻淬灭SiPM在该波段的探测效率过低，影响了其与闪烁体耦合后的闪烁探测器的性能。本项目在体电阻淬灭SiPM的基础上，通过P-on-N结构、浅结的设计，实现SiPM探测峰值波长蓝移和420nm附近探测效率提高；建立理论模型研究SiPM探测效率随结深、波长等因素的变化规律，为SiPM探测效率的实验研究提供理论依据；以LYSO闪烁体和SiPM通过一对一耦合，评估其探测灵敏度、能量分辨率等性能。该项目的研究，可以为低成本便携式的闪烁探测器的研制提供借鉴，在核辐射探测领域具有重要意义。

硅光电倍增器（SiPM），又名多单元光子计数器（MPPC）或多元盖革雪崩光电二极管（G-APDs），是近几十年来迅速发展起来的一种新型弱光探测器，在核辐射探测领域具有广阔的应用前景。闪烁体探测器是核辐射探测中常用的探测器，用于闪烁体探测器的闪烁体的发光波长通常在蓝紫光区，而硅光电倍增器在该波长范围内的探测效率有待提升。本项目的研究：1.通过设计SiPM的P-on-N结构、浅结结构来提高蓝紫光区的探测效率，制备出的SiPM期间探测效率的峰值向短波移动，在420nm处的探测效率达到20%，能够更好的与LYSO闪烁体耦合用于核辐射探测。2.通过建立模型，从理论上研究了SiPM 的探测效率随波长、过偏压、结深等变化的规律，得到了PDE的数学表达式，为PDE工艺研究提供理论依据。3.研究了SiPM的时间分辨特性，建立了基于SiPM的时间分辨光谱的测量系统，用于三硝基甲苯的时间分辨拉曼光谱的测量，有效的抑制了暗计数和荧光的影响，获得高信噪比的拉曼光谱，拓展了SiPM在光谱测量领域的应用。4. 研究了SiPM的光探测效率（PDE）和光学传话概率(Pct) 的二维(2D)微空间分布的一致性，由于电场的不均匀性，导致探测效率和光学传话概率的二维空间分布明显是不均匀的，在单元的拐角处比较大，给出了测量SiPM单个单元内的电场的二维空间分布的测量方法，得到的电场的分布可以指导SiPM的研发，优化其性能。