Layout and Assembly Technique of the GEM Chambers for the Upgrade of the CMS First Muon Endcap Station

Abstract

Triple-GEM detector technology was recently selected by CMS for a part of the upgrade of its forward muon detector system as GEM detectors provide a stable operation in the high radiation environment expected during the future High-Luminosity phase of the Large Hadron Collider (HL-LHC). In a first step, GEM chambers (detectors) will be installed in the innermost muon endcap station in the $1.6<\left|\eta \right|<2.2$ pseudo-rapidity region, mainly to control level-1 muon trigger rates after the second LHC Long Shutdown. These new chambers will add redundancy to the muon system in the $\eta$-region where the background rates are high, and the bending of the muon trajectories due to the CMS magnetic field is small. A novel construction technique for such chambers has been developed in such a way where foils are mounted onto a single stack and then uniformly stretched mechanically, avoiding the use of spacers and glue inside the active gas volume. We describe the layout, the stretching mechanism and the overall assembly technique of such GEM chambers.

23 pages, 24 figures

Cited by in corpus (4)

• The upgrade of the ALICE TPC with GEMs and continuous readout
• Quality Control of Mass-Produced GEM Detectors for the CMS GE1/1 Muon Upgrade
• Testing a large size triple GEM detector for the first station of the CBM-Muon Chambers with a high-intensity gamma source at GIF++ under large-area illumination
• Reduction of ion back flow using a quadruple GEM detector with various gas mixtures