批量塑闪单元条测试技术的研究

Development of a test bench for plastic scintillator counters for the DAMPE

寻找暗物质粒子是目前最有影响力的前沿课题之一,广泛受到世界各国重视。我国启动了暗物质粒子探测卫星(Dark Matter Particles Explorer,DAMPE)先导专项,致力研究这一科学问题。暗物质粒子探测卫星有效载荷由塑闪阵列探测器(Plastic Scintillator Detector Array,PSD)、硅阵列探测器、BGO(Bi2O3-Ge O2)量能器以及中子探测器组成,用于探测5 Ge V-10 Te V高能电子、γ及重离子能谱。中国科学院近代物理研究所承担了塑闪阵列探测器的研制工作,塑闪阵列探测器由82根塑闪单元模块采用横竖交叉结构组成,主要协助BGO量能器区分γ事件和电子事件,并作为硅阵列探测器的备份,探测Z=1-20的重离子事件。由于塑闪单元条模块存在较大的差异,所以搭建了一套具有较高测试效率的塑闪单元条批量测试平台,并对塑闪单元条进行宇宙线测试,得到其基本性能参数,如光衰减曲线、光衰减长度、相对光产额、能量分辨率以及探测效率。这为后续筛选出一致性较好并能满足功能需求的82根单元条提供了依据。

Background： Plastic scintillator detector array （PSD）, developed by Institute of Modem Physics, Chinese Academy of Sciences （IMPCAS）, is one of the most important parts in the payload of Dark Matter Particles Explorer （DAMPE） which is mainly used for the study of dark matter. As an anti-coincidence detector, and a charged-particle identification detector, the PSD is composed by 82 plastic scintillator counters. Purpose： Due to the difference among a batch of scintillator counters, it is necessary to develop a test bench with high test efficiency and also to obtain their performance, such as uniformity of light output, light attenuation length, peak of Minimum Ionizing Particle （MIPs） and detection efficiency simultaneously. Methods： A high-efficiency test bench, including electronic modules, data acquisition, analysis system, etc, has been constructed to study the characteristics of 24 scintillator counters with cosmic rays. Individual trigger module with dimensions of 34 cm×2 cm× 1 cm has been set up at different points of ±34 cm, ±17 cm and 0 cm. With this test bench, the light attenuation length and other main parameters of 20 counters have been investigated. Results and Conclusion： Through the high-efficiency test bench, data of 20 scintillator counters could be obtained simultaneously. After analysis of 185 counters＇ data, we can select 82 counters which fulfill all technology parameters provided by DAMPE and use in PSD.