Triple GEM tracking detectors for COMPASS
Triple GEM tracking detectors for COMPASS
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COMPASS 的三重 GEM 跟踪探测器
DOI：
10.1109/tns.2002.803891
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发表时间：
2002
影响因子：
1.8
通讯作者：
F. Simon
中科院分区：
文献类型：
--
作者：
B. Ketzer;M. Altunbas;K. Dehmelt;J. Ehlers;J. Friedrich;B. Grube;S. Kappler;I. Konorov;S. Paul;A. Placci;L. Ropelewski;F. Sauli;L. Schmitt;F. Simon
CERN SPS 的高光度固定目标实验 COMPASS 的小区域跟踪器包括一组 20 个大尺寸（31 /spl times/ 31 cm/sup 2/）气体电子倍增器（GEM）探测器。基于三个级联 GEM 箔中的气体放大，这些设备即使在非常高的粒子通量下也可以获得高增益和良好的空间分辨率。对于每个轨道，双坐标投影读数在两个投影上产生高度相关的信号幅度，从而可以解析靠近直径 5 厘米的中心失活区域的高占用区域中的多个命中。同时，暴露在光束下的材料也被最小化。将放大分为三个级联级可以实现 /spl sim/ 8000 的增益，这是在两个坐标上有效 (> 98%) 检测最小电离粒子所必需的，并且各个 GEM 箔上的电压已经相对适中。因此，与最初预见的双 GEM 结构相比，在给定增益下，当重电离粒子进入探测器体积时发生气体放电的概率降低了一个数量级以上。结合对放电现象进行广泛研发的其他策略，我们能够进一步降低能量和此类故障的概率。为了完全排除放电完全传播到读出条的罕见事件对前端芯片造成的永久性损坏，使用了外部电子保护电路。这些探测器的操作特性在实验室和光束中进行了检查，最小电离粒子的空间分辨率为 (46 /spl plusmn/ 3) /spl mu/m ，时间分辨率为 /spl sim/ 15 ns。在 2001 年运行的 COMPASS 中，总共安装了 14 个三重 GEM 探测器。介绍了高强度 /spl mu/ 光束调试阶段的第一个结果。
The small-area tracker of COMPASS, a high-luminosity fixed target experiment at CERN's SPS, includes a set of 20 large-size (31 /spl times/ 31 cm/sup 2/) gas electron multiplier (GEM) detectors. Based on gas amplification in three cascaded GEM foils, these devices permit to obtain high gain and good spatial resolution even at very high particle fluxes. A two-coordinate projective readout yields, for each track, highly correlated signal amplitudes on both projections, allowing to resolve multiple hits in high occupancy regions close to the central deactivated area of 5 cm diameter. At the same time, the material exposed to the beam is minimized. Splitting the amplification in three cascaded stages permits to achieve a gain of /spl sim/ 8000, necessary for efficient (> 98%) detection of minimum ionizing particles on both coordinates, already at relatively moderate voltages across individual GEM foils. As a consequence, the probability of a gas discharge to occur when a heavily ionizing particle enters the detector volume, is reduced by more than one order of magnitude at a given gain compared to the initially foreseen double GEM structure. In conjunction with other strategies resulting from extensive R&D on discharge phenomena, we were able to further reduce both the energy and the probability of such breakdowns. In order to completely exclude permanent damage to the front-end chip by the rare event of a discharge fully propagating to the readout strips, an external electronic protection circuit is used. The operational characteristics of these detectors were examined both in the laboratory and in the beam, where a spatial resolution for minimum ionizing particles of (46 /spl plusmn/ 3) /spl mu/m and a time resolution of /spl sim/ 15 ns were achieved. For the 2001 run of COMPASS, a total of 14 triple GEM detectors have been installed. First results from the commissioning phase in the high-intensity /spl mu/ beam are presented.