基于波形采样的CEPC电磁量能器读出单元测试系统

摘要

[Background] In the proposal of the circular electron positron collider (CEPC) scheme, readout unit consisting of a silicon photomultiplier (SiPM) and a plastic scintillator has become a research hotspot as one of the main options of electromagnetic calorimeter (ECAL).[Purpose]This study aims to optimize the detector prototype by setup an automated testing system to test, analyze and improve the performance of each readout unit of CEPC ECAL. [Methods]Based on the DT5751 waveform sampling plug-in module, SiPM drive circuit,stepper motor, low-voltage power supply (LVPS), relay,etc., the hardware of CEPC ECAL readout unit was built up whilst the software was developed with the LabVIEW. Repeated measurements were carried out to find the optimized parameters, and the SiPM calibration was performed. [Results]Experimental results show that proposed automated testing system satisfied basic requirements of CEPC ECAL readout unit. Setup of the testing platform of scintillator readout unit based on waveform sampling is option for CEPC ECAL and be used for SiPM calibration, scintillator uniformity of light output and reflective material study. [Conclusion]The experiment rwsult shows that the plastic scintillator strip with the ESR has the highest light yeild and the light yeild of 25μm coupled with SiPM 3 times than 10μm.%随着环形正负电子对撞机(Circular Electron Positron Collider,CEPC)方案的提出,由硅光电倍增管(Silicon Photomultiplier,SiPM)和塑料闪烁体组成的读出单元作为电磁量能器的预研方案之一,逐渐成为研究热点.在探测器预研阶段需要对读出单元性能进行充分研究,因此我们设计了一套自动化测试系统用于对读出单元进行测试、分析并改善其性能.利用DT5751波形采样插件、SiPM驱动电路板、步进电机、低压电源、继电器等完成硬件搭建,以LabVIEW为开发平台完成了软件的串行协议接口之间的通信,实现了读出单元的自动化测试,编写了相应的数据处理程序.在此基础上进行了SiPM刻度、闪烁体发光均匀性以及反射材料对光输出影响的研究.测试结果表明,ESR反射膜包裹的塑闪条具有最高的光输出,塑闪条耦合10μm像素SiPM的光输出为耦合25μm像素SiPM的三分之一.