Experimental ion mobility measurements in Ar-N2

M.A.G Santos,A.F.V Cortez,R Veenhof,J.M.C Perdigoto,P.N.B Neves,C.A.N Conde,F.P Santos,J Escada,F.I.G.M Borges

doi:10.1088/1748-0221/13/11/p11016

Abstract

Data on ion mobility is important to improve the performance of large volume gaseous detectors, since the detector signal can be influenced by the drift of the ions, namely in the cases where charge multiplication is used, for example in Multi-Wire Proportional Chambers (MWPCs) and in some Time Projection Chambers (TPCs). In the present work the results for the ion mobility measurements in Ar-N2 mixtures are presented, using an experimental setup and method already tested in previous work. The results for this mixture show the presence of only one peak for all gas ratios of Ar-N2, for reduced electric fields, E/N, in the range of 10–25 Td (2.4–6.1 kV⋅cm−1⋅bar−1), and 8 Torr (10.6 mbar) pressure, at room temperature.

Highlights

: Data on ion mobility is important to improve the performance of large volume gaseous detectors, since the detector signal can be influenced by the drift of the ions, namely in the cases where charge multiplication is used, for example in Multi-Wire Proportional Chambers (MWPCs) and in some Time Projection Chambers (TPCs)
One important feature of the system is the capability of controlling the voltage across the GEM (VGEM), which limits the maximum energy gained by the electrons as they move across the GEM holes, narrowing the variety of primary ions possibly produced
The mobility of the ions originated in Ar-N2 mixtures has been measured at different reduced electric fields E/N (10 Td and 25 Td) and 8 Torr pressure at room temperature (293 K)

Summary

Introduction

In the present work the results for the ion mobility measurements in Ar-N2 mixtures are presented, using an experimental setup and method already tested in previous work The results for this mixture show the presence of only one peak for all gas ratios of Ar-N2, for reduced electric fields, E/N, in the range of 10–25 Td (2.4–6.1 kV·cm−1·bar−1), and 8 Torr (10.6 mbar) pressure, at room temperature. According to Langevin’s theory [24], one limiting value of the mobility is reached when the electrostatic hard-core repulsion becomes negligible compared to the neutral polarization effect [25]. This limit is given by the following equation, Kpol = 13.88

Methods

Results

Conclusion