射线激发氧化锌发光及粒子甄别特性研究

Zinc oxide (ZnO) is an ultrafast scintillation material which has a promising future in pulsed radiation detection and imaging. However, ZnO crystals available have a deficiency in scintillation efficiency and luminescence time. The development of high quality ZnO scintillator is limited by the ambiguity of the scintillation mechanism, as well as the shortage of research about the direct response of ZnO to high energy particle irradiation..In this research, we focus on the characteristics of ZnO crystal to particle irradiation, including the dependence of scintillation property with the type and density of the ions doped, and its relationship with the irradiation particles. Meanwhile, explore the feasibility of particle discrimination techniques based on ZnO crystal. It is found that the luminescence decay time of ZnO depends on the irradiation particle, and different particle response could be separated through the luminescence time profile, which is typically called pulse shape discrimination (PSD). Detectors with ultrafast time response and PSD ability would be helpful to the measurement of mixed radiation field with high intensity, such as the neutron fields of ITER. After this research, we hope to achieve an exhaustive and systemic acquirement of the scintillation properties of ZnO crystals to high energy particle irradiation, improve the understanding of the scintillation mechanisms, and lay a foundation for high performance ZnO scintillator development and application.

氧化锌（ZnO）是一种超快闪烁发光材料，基于ZnO能够构建亚纳秒乃至皮秒时间分辨的探测系统，在脉冲辐射探测和辐射成像领域有非常好的应用前景。然而，现有的ZnO单晶材料作为闪烁体，发光性能并不理想，依然存在发光效率低、时间响应不够快等问题。射线激发ZnO发光基本特性研究的相对匮乏，以及对ZnO发光机理认识的不足，制约了高性能ZnO闪烁体的开发。.本项目旨在研究射线激发下ZnO超快发光的基本性质，研究发光特性同样品参数和激发射线之间的联系与规律。重点关注不同射线激发ZnO发光衰减时间不同这一特性，在探寻这一特性形成机理的同时，研究利用该性质实现粒子甄别探测的技术和方法，并尝试将该技术用于中子、伽马等混合辐射场的射线探测。期望通过项目研究，获得对ZnO闪烁体发光特性有一个较为全面、系统认识，促进对ZnO闪烁体射线响应发光机理的理解，为高性能ZnO闪烁体的开发和应用奠定基础。

本项目围绕ZnO晶体在射线激发下发光性质及其粒子甄别特性开展了理论和实验研究。根据研究计划，分别开展了低温条件下射线激发ZnO晶体发光基本特性、不同离子掺杂样品发光差异比较、发光特性随掺杂离子浓度的依赖关系等一系列研究工作，获得ZnO:Ga晶体发光性质与Ga离子掺杂的依赖关系。针对不同射线激发ZnO发光衰减时间不同这一独特性质，提出了一种基于局部折射率变化的光学非线性效应的理论模型，并根据理论模型计算得到衰减时间与激发粒子电离能力的规律曲线，理论曲线与实验结果变化趋势基本一致。此外，还探索了ZnO:Ga晶体用于脉冲中子探测、脉冲X射线成像等应用技术研究。本研究不仅促进了对ZnO闪烁发光特性和发光机理的认识，也为高性能ZnO闪烁体的开发和应用提供了重要支持。