基于载流子猝灭模型的闪烁体发光非线性效应理论分析及实验验证  

Theoretical analysis and experimental verification of scintillator luminescence nonlinearity based on carrier quenching model

作　　者：魏坤 黑东炜[1] 刘军[1] 徐青[1] 翁秀峰[1] 谭新建[1] Wei Kun;Hei Dong-Wei;Liu Jun;Xu Qing;Weng Xiu-Feng;Tan Xin-Jian(State Key Laboratory of Intense Pulsed Radiation Simulation and Effect,Northwest Institute of Nuclear Technology,Xi’an 710024,China;Department of Engineering Physics,Tsinghua University,Beijing 100084,China)

机构地区：[1]西北核技术研究所,强脉冲辐射环境模拟与效应国家重点实验室,西安710024 [2]清华大学工程物理系,北京100084

出　　处：《物理学报》2021年第24期84-90,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11905173);西北核技术研究所预先研究课题(批准号:13021901)资助的课题.

摘　　要：闪烁体探测器是辐射物理领域重要的探测器件,闪烁体作为其中的核心部分,其特性受到广泛研究,特别是闪烁体在高激发密度下的非线性效应由于其对测量结果的直接影响而得到格外关注.本文结合目前国内外闪烁体发光的相关理论,以载流子方程为基础,量化分析了激子的二阶猝灭效应对于载流子动力学过程的影响,着重计算分析了脉冲测量场景下不同激发密度产生的不同初始载流子浓度对于闪烁体光衰减曲线、光产额以及效率的影响.接着利用光致激发实验,研究了CeF_(3)闪烁体光产额与激发密度的关系,并利用载流子猝灭模型对实验数据进行了拟合,拟合曲线与实验数据一致性较高,并得到了CeF_(3)闪烁体10%非线性效应对应的能量密度阈值.通过本文研究工作建立的物理模型,结合不同的模型参数,可以实现多种闪烁材料发光非线性特性的预测和解释,对于理解及解决实验中遇到的闪烁体在高激发密度下产生的非线性效应问题具有重要作用.The scintillator detector is one of the most important detectors in the field of radiation detection and radiation physics.The characteristics and performance of scintillator that is a core part of the measurement system,are widely studied.Especially,the nonlinearity of scintillators under high excitation density has received more attention because of its direct influence on the measurement results.In this paper,physical modeling and experimental research on this problem are carried out in-depth.First,the second-order quenching effect of excitons on the scintillator luminescence process is quantitatively analyzed based on the carrier dynamic equation.The luminescence attenuation curves of scintillator under different initial carrier concentrations generated by different excitation densities are obtained.The relationship of the light yield and the efficiency of scintillator with the initial carrier concentration is analyzed,and the results show that with the increase of the initial carrier concentration,the light yield tends to be saturated and the light efficiency decreases.Then CeF_(3) scintillator is studied in the Z-scan photoluminescence experiment.The relationship between the light yield and the excitation density is obtained,and the experimental data can be fitted by the carrier quenching model well,which verifies the physical model.At the same time,the energy density threshold corresponding to the 10%nonlinearity of CeF_(3) scintillator is obtained.The physical model established in this paper can be used to predict and explain the nonlinear luminescence of various scintillation materials according to different parameters of crystal materials,which is important to understand and solve the nonlinearity problem of scintillators under high excitation density in practical application of radiation detection.

关 键 词：闪烁体非线性效应 载流子猝灭 光致激发 

分 类 号：TL812[核科学技术—核技术及应用]