Double-hit separation and dE/dx resolution of a time projection chamber with GEM readout

TL;DR

This paper evaluates a GEM-based TPC prototype's spatial resolution, track separation, and dE/dx measurement capabilities in a test beam, with simulation insights for optimizing particle identification.

Contribution

It presents the first results on close-track separation and dE/dx measurement with a GEM TPC, along with simulation-based optimization strategies.

Findings

Successful demonstration of track separation capability.

Achievement of dE/dx resolution suitable for particle identification.

Insights into readout granularity optimization from simulations.

Abstract

A time projection chamber (TPC) with micropattern gaseous detector (MPGD) readout is investigated as main tracking device of the International Large Detector (ILD) concept at the planned International Linear Collider (ILC). A prototype TPC equipped with a triple gas electron multiplier (GEM) readout has been built and operated in an electron test beam. The TPC was placed in a 1 T solenoidal field at the DESY II Test Beam Facility, which provides an electron beam up to 6 GeV/c. The performance of the readout modules, in particular the spatial point resolution, is determined and compared to earlier tests. New studies are presented with first results on the separation of close-by tracks and the capability of the system to measure the specific energy loss dE/dx. This is complemented by a simulation study on the optimization of the readout granularity to improve particle identification by dE/dx.