边缘限定-薄膜供料法制备Ce:Cs2LiYCl6晶体及其闪烁性能研究

Ce:Cs2LiYCl6 crystal has been proven to be a promising candidate for dual γ-ray and neutron detector in homeland security and nuclear safeguards applications because of its high energy resolution, fast decay time and high light yield of thermal neutron. Comparing with Bridgman method, the edge-defined film-fed (EFG) has much more advantages, such as fast growth and high efficiency. Under the same conditions, the crystal growth rate of EFG method is 10 times faster than that of Bridgman method. Crystal with different can also be obtained by the EFG method.EFG die can reduce the difficulty of crystal processing; overcome the limitations of Bridgman method. The project will set up the growth device under the guidance of EFG growth principle, innovate growth method, solve key technology, design different shape of die, the growth rate will be 15mm/h, high quality Ce:CLYC crystal with different shaped and dimension 20 × 20 × 30mm rectangular shape and 3 × 25 × 30mm sheet shape will be obtained. The effect of Ce3+ ions in the crystal properties will be studied; the basic properties and scintillation characterization will be measured. Light yield of γ-ray will be 22,000 Photons/MeV, energy resolution 3~4%, light output of neutron 73,000 photons/neutron. This research will supply the new functional materials for social needs and science research.

Ce:Cs2LiYCl6（Ce:CLYC）能量分辨率高、快衰减，热中子探测光产额高，是具有γ射线、中子双探测能力的闪烁晶体，在核科学、空间科学等领域有重要应用。Bridgman法可制备Ce:CLYC但存在局限性。边缘限定-薄膜供料法（EFG）能够克服Bridgman法局限，晶体生长速度比Bridgman法快10倍，并可通过模具设计获得异型晶体，降低加工难度。本项目拟在EFG法生长原理指导下，创新生长方法，解决关键技术问题，生长速度达到15mm/h，设计独特模具，获得尺寸约20×20×30mm长方体、3×25×30mm片状等多种形状的高质量晶体。系统表征晶体闪烁性能，研究Ce离子对晶体性能的影响，实现晶体γ射线光产额22,000 Photons/MeV，能量分辨率3~4%，中子光输出73,000 photons/neutron，为γ射线和中子双探测器提供新型闪烁材料。

γ射线、中子探测在核医学、核科学、航空航天及军事领域有重要应用。Ce:Cs2LiYCl6（Ce:CLYC）晶体利用γ射线和中子两种信号衰减时间差异，通过脉冲形状光谱PSD (pulse-shape discrimination)区分两种信号，可以解决复杂环境辐射探测难点问题，实现γ射线和中子同时探测。Ce:CLYC具有能量分辨率高、快衰减，热中子探测光产额高等优点，γ射线/中子双探测性能优异。. 当前采用bridgeman法制备的Ce:CLYC晶体，存在第二相等问题，降低了晶体质量，制约晶体应用。项目运用边缘限定-薄膜供料法（EFG）制备高质量Ce:CLYC晶体，系统研究了生长装置及工艺参数，部分解决了晶体缺陷对晶体质量的影响；研究了晶体的加工工艺及封装方法；获得了不同Ce离子掺杂晶体紫外可见荧光光谱、荧光寿命及X射线激发发射光谱；测试晶体能量分辨率等闪烁性能。. 取得的成果主要有：1.创造性搭建生长装置，确定最佳工艺，稳定获得高质量3×25×30mm晶体。2.掌握了晶体缺陷产生机理，解决缺陷产生的技术问题，显著提高晶体质量。3.对 Ce 0.5%、3%、 5%的Ce:CLYC晶体进行性能研究。在371 nm和403 nm有两个发射峰。Ce3+含量在0.5%时，发光强度最高。随着掺杂浓度增加，发射峰位置发生红移；衰减时间也逐渐增加，0.5%、3%、 5%掺杂浓度下，衰减时间分别为28.9654 ns、40.1416 ns、43.3894 ns。X射线激发发射光谱分别是300 nm、370 nm和404 nm。300 nm附近的发射峰，对应于芯价发光。4. 137Cs伽马射线激发下的能量分辨率为6.8%；品质因数FOM数为3.39。显示了晶体具有良好的γ射线、中子区分度。