光子晶体人工微结构对无机闪烁晶体时间特性的影响

High time-resolution scintillation detection systems are becoming increasingly demanding in space exploration, particle physics experiments, nuclear weapons research and nuclear medicine imaging. As the core of the scintillation detection system, The scintillators of traditional theory and method research is not breakthrough in recent decades. With the development of photonic crystal technology, a new method and a new way to improve the performance of inorganic scintillators by photonic crystals have emerged. At present, the research is in the initial stage, the research area is mainly focused on the realization of higher light extration and larger area of artificial photonic crystal microstructure. It is not found that photonic crystal is used to improve the time resolution of scintillators. Considering the requirement of high time-resolution scintillation detection system and its application prospect, this project aims to study the effect of photonic crystal layer on the fluorescence propagation behavior of scintillator to reveal its internal mechanism. This work will improve the time-resolution of scintillation detection system by using photonic crystals and provide a scientific basis for photonic crystals in space exploration, high-energy physics experiments and medical imaging.

高时间分辨闪烁探测系统在空间探测、粒子物理实验、核武器研究和核医学成像等领域的需求越来越强烈。闪烁体作为闪烁探测系统的核心，其传统的理论与方法研究在近几十年没有较大的突破。随着光子晶体技术的发展，出现了一种利用光子晶体提高无机闪烁晶体性能的新方法和新途径。该研究处于起步阶段，研究方向主要集中在实现更高的光输出和大面积制备光子晶体人工微结构，目前尚未有利用光子晶体改善闪烁晶体时间特性的研究。考虑到高时间分辨闪烁探测系统的需求及其应用前景，本项目拟通过研究光子晶体层对闪烁体荧光传输行为的调控作用，建立光子晶体影响闪烁晶体发光时间特性的物理过程模型，揭示其内在机制。从而为利用光子晶体改善闪烁探测系统的时间分辨率，及其在空间探测、高能物理实验和医学成像等领域的应用提供科学基础支撑。

闪烁晶体的光输出及其时间分布是决定闪烁晶体探测器性能的关键因素。高能物理实验中对事件的精确标记以及飞行时间成像技术对高时间分辨闪烁体探测系统的需求正在推动着优化闪烁晶体探测器时间分辨率的研究。然而大多数由重材料制成的无机闪烁体具有高折射率，限制了光提取效率并影响了时间分辨。本项目针对目前通过光子晶体克服这一光提取问题的较新方法，利用共形薄膜的光子晶体修饰LYSO闪烁晶体的光输出面，完成了对该光子晶体修饰的闪烁体探测器的时间分辨的测定。实验表明，耦合了共形薄膜的LYSO晶体，其时间分辨率以及能量分辨率分别提升了12.50%和3.24%；结合出射光子数在时间上分布的模拟计算，表明高密度闪烁晶体通过耦合光子晶体能够提高第一纳秒内输出的光子数并缩短输出脉冲的衰减时间。本项目验证了光子晶体提升闪烁晶体探测器时间分辨的正确性，为进一步发展和应用该新技术于空间探测、高能物理实验和医学成像等领域提供了理论与技术基础。