宽能区可变视野的三维位置灵敏闪烁探测器伽马成像研究

Gamma-ray imaging is an effective method to identify the gamma-emitting nuclides and determine their position and distribution, which is widely used in nuclear security and safety, radiation monitoring, radioactive waste disposal and nuclear emergency management. The 3-D position sensitive semiconductor detector combines the advantages of gamma camera and Compton imaging to realize 4π field of view and cover a wide energy range. This is very important for gamma ray detection in complex and unknown situation. However, the detection efficiency and angular resolution are difficult to be further improved. A novel method is presented in this proposal. Gamma-ray imaging with 4π field of view and wide energy range can be realized using 3-D position sensitive scintillation detector, which is a telescopic multi-layer scintillator design. Both the detection efficiency and the angular resolution can be significantly improved.

伽马成像是确定伽马放射性核素种类、位置及空间分布的有效手段，在核安全、核辐射监测、放射性废物处理、核应急等领域发挥着重要作用。三维位置灵敏半导体探测器的引入，结合了伽马相机和康普顿成像的特点，可以实现宽能区的4π视野伽马成像，对于应对复杂未知的辐射场景具有重要意义，但探测效率、角度分辨难以进一步提升。本课题提出了一种新的方法：采用多层闪烁体组成可分割的三维位置灵敏闪烁探测器，进行宽能区的4π视野成像，可显著提升探测效率和角度分辨。

本项目针对核安全、辐射监测等应用中对伽马成像的宽能区、大视野、高效率、高分辨的迫切需求，提出了覆盖宽能区且兼顾视野、效率和角度分辨的新型伸缩式三维位置灵敏闪烁探测器结构，并利用双端读出的作用深度信息简化了探测器的读出系统。基于国产新型闪烁陶瓷材料构建的原型机同时实现了优于4mm的位置分辨和对511keV优于8%的能量分辨，对核安全和核医学等相关应用和探测器设计具有较高价值。原型机可实现全视野成像，且对662keV的探测效率高于10%，对122keV和662keV伽马射线的角度分辨均优于10度。基于国产闪烁陶瓷材料构建的原型机成本较低且读出简单，兼顾了宽能区大视野高角度分辨成像和能谱测量，能够应对复杂未知环境中对伽马成像的要求，有利于后续的产品化改进和应用推广。