Ion mobility measurements in Ar-CO2, Ne-CO2, and Ne-CO2-N2 mixtures, and the effect of water contents
Ion mobility measurements in Ar-CO2, Ne-CO2, and Ne-CO2-N2 mixtures, and the effect of water contents
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Ar-CO2、Ne-CO2 和 Ne-CO2-N2 混合物中的离子淌度测量以及水含量的影响
DOI：
10.1016/j.nima.2018.07.008
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
A. Szabo
中科院分区：
文献类型：
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作者：
A. Deisting;C. Garabatos;A. Szabo
本文介绍了一种在室温和常压下测量混合气体离子迁移率的探测器。该检测器由一个标准的三重GEM放大区和一个离子漂移区组成。本文提出了一种通过对阴极线栅记录信号进行微分来测量离子到达阴极线栅时间的方法。仿真结果证明了该方法的准确性和鲁棒性。测量不同气体混合物中的离子迁移率，同时施加200 V cm-1至1100 V cm-1的不同漂移场值。根据Blanc定律外推到Ar-CO 2混合物中的测量结果，我们发现漂移（簇）离子种类在纯氩气中的约化迁移率为1.94±0.01 cm 2 V− 1 s− 1，在纯二氧化碳中为1.10±0.01 cm 2 V− 1 s− 1。将同样的方法应用于我们在Ne-CO 2中的测量，在纯氖和二氧化碳中的约化迁移率分别为4.06±0.07 cm 2 V− 1 s− 1和1.09±0.01 cm 2 V− 1 s− 1。N2与Ne-CO2（90-10）的混合物在一定程度上降低了迁移率。对于未来ALICE时间投影室的基准气体混合物，Ne-CO 2-N 2（90-10-5），测量到的漂移离子的约化迁移率为2.92±0.04 cm 2 V− 1 s− 1。用Ar-CO2（90-10）和Ne-CO2（90 -10）测定了气体中水含量从70 ppm到2000 ppm的离子迁移率。加入几百ppm的水后，观察到离子迁移率略有下降。
A detector has been constructed for measuring ion mobilities of gas mixtures at atmospheric pressure and room temperature. The detector consists of a standard triple GEM amplification region and a drift region where ions drift. A method has been developed to measure the ions’ arrival time at a cathode wire-grid by differentiating the recorded signals on this electrode. Simulations prove that this method is accurate and robust. The ion mobility in different gas mixtures is measured while applying different drift field values ranging from 200 V cm− 1 to 1100 V cm− 1. From an extrapolation of a Blanc’s law fit to measurements in Ar-CO 2 mixtures we find the reduced mobility of the drifting (cluster) ion species in pure argon to be 1.94±0.01 cm 2 V− 1 s− 1 and in pure carbon-dioxide to be 1.10±0.01 cm 2 V− 1 s− 1. Applying the same procedure to our measurements in Ne-CO 2 yields 4.06±0.07 cm 2 V− 1 s− 1 and 1.09±0.01 cm 2 V− 1 s− 1 for the reduced mobilities in pure neon and carbon-dioxide, respectively. Admixtures of N 2 to Ne-CO 2 (90-10) reduce somewhat the mobility. For the baseline gas mixture of the future ALICE Time Projection Chamber, Ne-CO 2-N 2 (90-10-5), the measured reduced mobility of the drifting ions is 2.92±0.04 cm 2 V− 1 s− 1. Ion mobilities are examined for different water content ranging from 70 ppm to about 2000 ppm in the gas using Ar-CO 2 (90-10) and Ne-CO 2 (90-10). A slight decrease of ion mobility is observed for the addition of several hundred ppm of water.