锂基中子探测闪烁共晶的设计、制备及性能表征

There are more challenges on the neutron detection materials with the development of neutron detection technique. The traditional neutron detection materials can not satisfy the application requirements. Then the neutron detection scintillators are attractive in scintillator research. The Li based neutron detection eutectic is composed of scintillation phase and Li based nuclear reaction phase in which two phases alternate in micro size. The advantage of eutectic in neutron detection is the design of composition and micro structure. And then the neutron detection performances can be optimized. The scintillators with great performances was selected as scintillation phase and Li based materials which can form eutectic with selected scintillators was used as the other phase. According to the Monte-Carlo simulation of nuclear reaction process, scintillation process and light propagation, the micro structure of the eutectic is designed to optimize the performances of the eutectic. The controllable preparation of two phases is achieved by optimize the crystal growth parameters. In the investigation, the work will be carried out according to the performances of scintillators and thermodynamic phase equilibrium theory. The principles are obtained through the results of design of the composition and micro structure. The Li based neutron detection eutectic with great performances in application will be obtained.

中子探测技术的发展对于中子探测材料提出了更高的要求。传统的中子探测材料已经无法满足这些要求，因此中子探测闪烁体成为闪烁材料领域研究的热点。锂基中子探测闪烁共晶由闪烁相与锂基核反应相共同组成，两相交替排列在微观尺度上结合为一体成为复合晶体。因此共晶在中子探测中的优势就在于可进行组分和微结构的设计，实现中子探测性能的优化。选用具有优异闪烁性能的闪烁晶体作为闪烁相，匹配可与该闪烁晶体形成共晶的含Li化合物组成共晶。根据核反应过程与闪烁与光传播过程的蒙特卡洛模拟，设计共晶的微结构，优化共晶的中子探测性能。通过优化生长工艺实现两种晶相微结构的可控制备。在中子探测闪烁共晶的研究中根据材料的闪烁性能与机理的分析，辅以热力学相平衡理论，通过组分设计与实验相结合的方式，围绕“设计→制备→表征→优化”这一过程，总结相关的规律和认识，建立相关理论。研发出满足应用需求的高性能中子探测锂基闪烁共晶。

锂基中子探测闪烁共晶由闪烁相与锂基核反应相共同组成，两相交替排列在微观尺度上结合为一体成为复合晶体。因此共晶在中子探测中的优势就在于可进行组分和微结构的设计，实现中子探测性能的优化。在本研究中通过设计与制备获得CsI-LiI、CsI-LiI:Na 、CsI-LiCl、CsI-LiCl:Na四种中子探测闪烁共晶，研究了坩埚形状、生长速度、温度梯度和组分偏析对于共晶质量的影响。同时针对锂基卤化物共晶易潮解的问题，研发出一套针对潮解材料的加工和封装工艺。通过对这四种共晶的闪烁性能进行研究，建立起其可能的闪烁机制模型，并对不同组分及掺杂锂基闪烁共晶的中子探测性能进行了初步的研究。研究了缺陷对于共晶中的CsI组分闪烁发光慢分量的影响，还研究了缺陷与CsI闪烁发光之间的关系。在研究中还使用Fortran语言编写了基于光子追踪技术的蒙特卡洛程序对闪烁光在不同几何形状的晶体中的传输过程进行了模拟，研究了几何形状、表面状态等因素对于光传输和收集的影响作用。通过本项目的研究掌握了锂基探测闪烁共晶的设计与制备的方法。