大动态范围闪烁晶体荧光模拟器的设计  

Design of fluorescence simulator with large dynamic range for scintillation crystal

作　　者：项天[1] 金西[1] 董家宁[1] 封常青[2] 刘树彬[2] 

机构地区：[1]中国科学技术大学物理系,安徽合肥230026 [2]中国科学技术大学近代物理系,安徽合肥230026

出　　处：《光学精密工程》2014年第2期304-310,共7页Optics and Precision Engineering

基　　金：中国科学院空间科学战略性先导科技专项资助项目(No.XDA04040202-4)

摘　　要：针对暗物质粒子探测卫星(DMPES)锗酸铋(BGO)量能器探测单元的标定需要,设计了一种用发光二极管(LED)作为光源的闪烁晶体荧光模拟器。首先,利用光电倍增管(PMT)测量BGO晶体在宇宙线辐射下的荧光脉冲,对脉冲波形建模拟合,并将波形存储到可编程信号发生器中。然后,选择一种峰值波长与BGO晶体的荧光发射波长相近,且其光通量与工作电流的线性度较好的LED,设计LED驱动电路,令LED的工作电流与模拟器输入的模拟电压信号幅度成正比。最后,利用信号发生器输出模拟的BGO晶体荧光脉冲波形至驱动电路,使LED发光,并利用积分球将LED的荧光通过光纤均匀地输出到多个PMT。实验结果表明:模拟器光脉冲测试结果与对BGO晶体实际测试的结果相似,光强覆盖PMT的2,5,8个打拿极(Dynode)输出,动态范围达4.11×103倍,满足暗物质粒子探测卫星BGO量能器地面检测系统的需求。该荧光模拟器也可用于同类闪烁晶体探测器系统的检测和标定。A scintillation crystal fluorescence simulator with a large dynamic range was developed based on a Light emitting Diode （LED） for calibrating the Bismuth Germanium Oxide（BGO） calorimeterdetectors of the Dark Matter Particle Explore Satellite（DMPES）.Firstly,a Photo Multiplier Tube（PMT） was used to measure the fluorescent pulse of a BGO crystal,create an exponential model for the shape of fluorescence pulse and to store the exponential waveform into a programmable signal generator.To match the feature of BGO,the LED with a similar peak wavelength to the BGO crystal and a good linearity between current and light intensity was chosen,and the LED driver with a output current in proportion to the input voltage signal was designed.Finally,the signal generator output the simulated fluorescence pulse of BGO crystal to the driver and allowed the LED to lighting,then,it transmitted the pulse to PMTs via an integrating sphere with optical fibers.Experiment results show that the pulse shape from the real BGO is coincident with that from the simulator and the dynamic range of output light intensity covers all three dynodes,which is up to 4.11 × 103.The simulator satisfies the need of ground-based testing for DMPES BGO detectors and can also be used for other similar scintillation crystal detectors.

关 键 词：暗物质粒子探测卫星 锗酸铋晶体(BGO) 模拟器 大动态范围 

分 类 号：O572.2[理学—粒子物理与原子核物理] TL814[理学—物理]