Simulation of Space-Charge Effects in an Ungated GEM-based TPC
Simulation of Space-Charge Effects in an Ungated GEM-based TPC
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基于非门控 GEM 的 TPC 中空间电荷效应的仿真
DOI：
10.1016/j.nima.2013.04.020
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发表时间：
2012
影响因子：
1.4
通讯作者：
M. Vandenbroucke
中科院分区：
文献类型：
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作者：
F. Böhmer;M. Ball;S. Dorheim;C. Höppner;B. Ketzer;I. Konorov;S. Neubert;S. Paul;J. Rauch;M. Vandenbroucke
时间投影室（TPC）在高速率实验中的应用的一个基本限制是缓慢漂移的离子在活性气体体积中的积累，这损害了漂移场的均匀性，从而影响了检测器的分辨率。传统上，通过使用离子门控结构来克服该问题。然而，这种方法引入了大的死区时间，并将触发速率限制在每秒几百次。通过使用气体电子倍增器（GEM）箔进行气体放大，可以从设置中消除离子门，这本质上抑制了离子的回流。这使得TPC在高速率下的连续操作是可行的。在这项工作中，Monte Carlo模拟的离子空间电荷的建立在一个GEM为基础的TPC和由此产生的漂移失真的校正进行了讨论，基于现实的数字在一个三GEM放大堆栈的离子回流。在FAIR的未来实验中的TPC作为实验环境的一个例子。模拟结果显示，空间电荷密度高达65 fCcm − 3，导致电子漂移失真高达10 mm。激光校准系统的应用，以纠正这些失真的影响。基于探测器物理和响应的全面模拟，我们表明，它是可能的，以纠正漂移失真，并保持良好的动量分辨率的GEM-TPC。
A fundamental limit to the application of Time Projection Chambers (TPCs) in high-rate experiments is the accumulation of slowly drifting ions in the active gas volume, which compromises the homogeneity of the drift field and hence the detector resolution. Conventionally, this problem is overcome by the use of ion-gating structures. This method, however, introduces large dead times and restricts trigger rates to a few hundred per second. The ion gate can be eliminated from the setup by the use of Gas Electron Multiplier (GEM) foils for gas amplification, which intrinsically suppress the backflow of ions. This makes the continuous operation of a TPC at high rates feasible. In this work, Monte Carlo simulations of the buildup of ion space charge in a GEM-based TPC and the correction of the resulting drift distortions are discussed, based on realistic numbers for the ion backflow in a triple-GEM amplification stack. A TPC in the future p¯anda experiment at FAIR serves as an example for the experimental environment. The simulations show that space charge densities up to 65fCcm−3are reached, leading to electron drift distortions of up to 10mm. The application of a laser calibration system to correct these distortions is investigated. Based on full simulations of the detector physics and response, we show that it is possible to correct for the drift distortions and to maintain the good momentum resolution of the GEM-TPC.
DOI：
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发表时间：
2009-11
期刊：
arXiv: Instrumentation and Detectors
影响因子：
--
作者：
W. Erni;I. Keshelashvili;B. Krusche
通讯作者：
W. Erni;I. Keshelashvili;B. Krusche