Performance of a Large-area GEM Detector Read Out with Wide Radial Zigzag Strips

TL;DR

This paper evaluates a large-area GEM detector with innovative zigzag readout strips that significantly reduce electronic channels while maintaining high efficiency and good angular resolution, tested in hadron beams at Fermilab.

Contribution

It introduces a novel zigzag strip geometry for GEM detectors that cuts channel count by a third without sacrificing resolution or efficiency.

Findings

Detection efficiency of 98.4%

Angular resolution of 193 microradians

Zigzag geometry reduces channels by 66%

Abstract

A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run along the radial direction with an azimuthal pitch of 1.37 mrad to measure the azimuthal phi-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5%. The detection efficiency of the detector is (98.4+-0.2)%. When the non-linearity of the zigzag-strip response is corrected with track information, the angular resolution is measured to be (193+-3) urad, which corresponds to 14% of the angular strip pitch. Multiple Coulomb scattering effects are fully taken into account in the data analysis with the help of a stand-alone Geant4 simulation that estimates interpolated track errors.