【作者】 郑晓翠；

【导师】 李玉兰；

【作者基本信息】 清华大学 ， 核科学与技术， 2006， 硕士

【摘要】 GEM探测器是一种新型微单元结构气体探测器,在粒子物理实验及低能X射线成像系统中有着较大的应用前景。本文首先研制了一个三级GEM探测器,并对其漏电流、噪声水平、放大特性以及能量分辨率等性能进行了测试。实验表明该三级GEM探测器的漏电流和噪声较小,有效增益可达105以上,对5.9KeV的X射线能量分辨率可达24%,达到了国际相当水平。GEM探测器具有许多优势,其中之一就是其读出方式灵活多样。论文根据读出方式的不同原理,将现有的读出方式分为四种,并分别介绍了这四种读出方式的基本原理、结构及工作过程。在综合考虑它们各自的优缺点的基础上,本文提出采用印刷电路技术,通过FET开关阵列读出GEM探测器信号的方法,这种信号读出方式具有制作工艺简单、参数可调、成本低等优点,通过对它的研究,可以为我们随后采用厚膜技术及TFT技术读出GEM探测器提供设计依据。论文成功的完成了读出电路的设计,实测证明,其动态范围可达7.3×104、积分非线性小于0.324%、灵敏度为2.54 mV/pC、可实现30帧/秒的实时成像。本文阐述FET开关阵列读出方式各性能指标的测试方法和测试结果。在充分了解GEM探测器及FET开关阵列性能的基础上,利用实验室现有的数据获取系统,搭建了一套基于FET开关阵列读出方式的GEM探测器成像系统,利用55Fe放射源和微焦点X光机进行了成像实验,初步分析了系统的空间分辨率与反差灵敏度、读出阵列不一致性的修正以及系统输出与X光机工作电流之间的关系等问题。更多还原

【Abstract】 GEM Detector is a new kind of micro-pattern gas detector, and has great prospect in particle physics experiment and low energy X-ray imaging system. We are developing a triple GEM, and testing the basic performances such as leakage current, noise, effective gain and energy resolution. From our test, the leakage current and noise are both low, effective gain could reach 105, and energy resolution is about 24% with X-ray at 5.9 KeV.GEM detector has many advantages. One of them is the flexible readout methods. Based on the differences of their working principles, the existing readout methods could be divided into four classes. Their working principles and structures are introduced. According to the advantages and disadvantages of these resdout methods, we are investigating the pixel readout of GEM detector with an array of filed effect transistors (FETs) using PCB technology. This readout method has advantages of simple manufacture, flexible parameters, low cost and can provide us primary data for the future readout method based on thick-film technology and TFT. From our test, the dynamic range could reach 7.3×104, INL is less than 0.324%, sensitivity is 2.54 mV/pC, and readout could be in real time (30 frames/sec). The test methods and test results are analyzed in this paper.After accumulating enough knowledge about GEM detector and FET switches array, using our lab’s DAQ system, we are developing a GEM detector imaging system based on FET switches array readout method. The imaging experiment with 55Fe and micro-focus X-ray generator is done. And the spacial resolution, the contrast sensitivity, the variance between readout units, the relationship between system output and X-ray generator working current are analyzed in this paper.更多还原