基于单片有源像素传感器的探测模块测试研究

Test study of detector modules based on monolithic active pixel sensor

硅像素探测器因具有优异的空间分辨率、极高的耐计数能力和较低的功耗等优点,近年来已被广泛应用于高能对撞机实验的顶点探测器和内径迹探测器.基于MIMOSA28芯片的硅像素探测器研究是北京谱仪Ⅲ漂移室内室的升级预研方案之一,该方案计划建造一个漂移室内室1/10规模的模型.探测模块是该模型的基本探测单元.为了对探测模块的性能进行研究,搭建了实验室测试系统.该系统主要由五层探测模块、读出电子学系统以及数据获取系统组成.本文围绕带有触发标记的连续数据读出方法的实现、探测模块的噪声水平和放射源响应测试以及击中位置重建算法研究展开.测试结果验证了探测模块工作性能良好,触发读出逻辑正确,而且重建算法准确有效,为后续探测模块性能的进一步研究奠定了基础.

Silicon pixel detectors are widely used as vertex detectors or inner trackers in high-energy collider experiments because of their excellent spatial resolution,extremely high counting capability and low power consumption.The study of the silicon pixel detector based on the monolithic active pixel sensor(MAPS)is one of the R&D schemes for upgrading the inner chamber of the Beijing spectrometerⅢ(BESⅢ)drift chamber(MDC).It is planned to build a 1/10 scale prototype of the inner chamber.The detector module is the basic component of the prototype,consisting of ten MIMOSA28 chips thinned to 50μm,a flexible cable and a carbon fiber support.In order to study the performance of the module,a test system is set up.The system is composed mainly of five-layer modules,readout electronics and data acquisition system.This article focuses on the realization of the continuous data readout method with trigger marking function,the measurement of the noise level of the detector modules,the module response test by a radioactive source,and the study of the hit reconstruction algorithm.The test of trigger readout logic verifies the correctness of the continuous readout method with trigger marking.It can be concluded that analyzing consecutive three frames data(the previous frame,the current frame and the next frame)of each valid trigger will not lead to effective hit data loss.The noise level of the detector module is tested.The results show that the fixed pattern noise(FPN)is 0.253 mV,and the temporal noise(TN)is 1.65 mV.The fake hit rate is less than 10^(-5)that can be ignored when the chip threshold is set to be above 4s of noise.Two algorithms for hit reconstruction(i.e.adjacent method and comparison method)are studied and compared.When the average number of fired pixels caused by each hit is 2.562 and more than four hits in each frame of data,the adjacent method can find all of the fired pixels to be faster.During the test,the detector module and the electronics are proved to work well.These studies lay a foundation for further testing the performance of the detector prototype.