一种低噪声硅微条探测器读出电子学系统的设计

硅微条探测器空间分辨率高、工作性能稳定, 广泛地应用于空间高能粒子探测领域. 如费米gamma射线空间望远镜(Fermi Gamma-ray Space Telescope, FGST)以及阿尔法磁谱仪(Alpha Magnetic Spectrometer 2, AMS-02)的径迹探测器中都采用了高位置分辨率的硅微条探测器. 基于硅微条探测器在空间观测领域的应用前景, 针对硅微条探测器单元设计了一套低噪声的电子学读出系统. 整个电子学系统分为前端电子学、数据获取电路和上位机软件. 前端电子学为提高集成度, 采用了一款电荷读出芯片VATAGP8, 实现了多通道、低噪声的电荷信号测量; 数据获取电路使用现场可编程门阵列(Field Programmable Gate Array, FPGA)实现了对前端电子学的时序控制以及对测量信号的采集控制; 上位机用来接收、处理数据获取电路采集的信号数据. 在对电子学通道的线性、基线、噪声等性能进行测试之后, 得到系统在0--200fC电荷输入范围内的线性增益约为13.41bin/fC, 积分非线性小于1%, 噪声小于0.093fC. 为了验证电子学读出系统对硅微条探测器单元的读出能力, 将两者集成在一起并测试了宇宙线缪子的能量沉积, 得到读出电子学系统的信噪比大于32, 缪子的电离损失能谱与Landau-Gaussian分布符合较好, 能够满足硅微条探测器单元读出电子学的设计要求.

Design of a Low-noise Electronic Readout System for Silicon Micro-strip Detector

Silicon micro-strip detector has high spatial resolution and good stability. It is widely used in the field of high energy particle detection in space, e.g. Fermi Gamma-ray Space Telescope (FGST) and Alpha Magnetic Spectrometer 2 (AMS-02) mission. They both used silicon micro-strip detector as tracker. Considering the perspective of silicon micro-strip detector in astronomical field, a low-noise electronic system was designed for its signals'' readout in this paper. The electronic readout system consists of three parts: front-end electronics, data acquisition circuit, and host computer software. In order to implement a high integrated system, a charge measurement chip VATAGP8 with multi-channel and low-noise is adopted in the front-end electronics. The data acquisition circuit with the help of field programmable gate array (FPGA) realizes the timing control and the signal acquisition for front-end electronics. The host computer software is responsible for receiving and processing the data collected by the data acquisition circuit. We finished electronic performance test for the system. The gain of charge measurement is about 13.41bin/fC in its dynamic range of 0--200fC. The integral non-linearity is less than 1%, and the noise of pedestal is less than 0.093fC. Furthermore, for verifying the performance of the detector system, a silicon micro-strip sensor was integrated to the readout electronics. We tested the response of the cosmic ray Muon''s energy deposited in silicon micro-strip detector. It shows that the signal-to-noise (signal peak of energy deposited vs pedestal''s noise) ratio of the detector system is more than 32. The spectrum of ionization energy loss of Muon is well matched to the Landau-Gaussian distribution. The electronic readout system can meet the requirements of the silicon micro-strip detector.