Cosmic ray tests of a GEM-based TPC prototype operated in Ar-CF4-isobutane gas mixtures

TL;DR

This study evaluates a GEM-based TPC using Ar-CF4-isobutane gas mixtures under magnetic fields, demonstrating its potential advantages for future collider experiments through measurements of gas gain, diffusion, and spatial resolution.

Contribution

It provides experimental validation of Ar-CF4-isobutane mixtures for TPCs, highlighting improved properties over traditional gases in high magnetic fields.

Findings

Reduced transverse diffusion in Ar-CF4-isobutane mixtures

Achieved high gas gain suitable for TPC operation

Maintained good spatial resolution under magnetic fields

Abstract

Argon with an admixture of CF4 is expected to be a good candidate for the gas mixture to be used for a time projection chamber (TPC) in the future linear collider experiment because of its small transverse diffusion of drift electrons especially under a strong magnetic field. In order to confirm the superiority of this gas mixture over conventional TPC gases we carried out cosmic ray tests using a GEM-based TPC operated mostly in Ar-CF4-isobutane mixtures under 0 - 1 T axial magnetic fields. The measured gas properties such as gas gain and transverse diffusion constant as well as the observed spatial resolution are presented.