Construction and performance of large-area triple-GEM prototypes for future upgrades of the CMS forward muon system

Abstract

At present, part of the forward RPC muon system of the CMS detector at the CERN LHC remains uninstrumented in the high-η region. An international collaboration is investigating the possibility of covering the 1.6 > |η| > 2.4 region of the muon endcaps with large-area triple-GEM detectors. Given their good spatial resolution, high rate capability, and radiation hardness, these micro-pattern gas detectors are an appealing option for simultaneously enhancing muon tracking and triggering capabilities in a future upgrade of the CMS detector. A general overview of this feasibility study will be presented. The design and construction of small (10 × 10 cm 2) and full-size trapezoidal (1 × 0.5 m 2) triple-GEM prototypes will be described. During detector assembly, different techniques for stretching the GEM foils were tested. Results from measurements with x-rays and from test beam campaigns at the CERN SPS will be shown for the small and large prototypes. Preliminary simulation studies on the expected muon reconstruction and trigger performances of this proposed upgraded muon system will be reported. © 2011 IEEE

Test beam results of the GE1/1 prototype for a future upgrade of the CMS high-η muon system

“…5 shows the cluster size and achieved space resolution. 1 One VFAT threshold unit corresponds to a charge of ≈ 0.08fC at the input channel comparator stage. In one campaign a strong magnetic field was used to validate the detector performance in an environment similar to the high-η region of the CMS muon endcap.…”

“…T he GEM collaboration (GEMs for CMS) is developing a new prototype detector in view of the CMS high-η upgrade [1]. The CMS [2] endcap region 1.6 < |η| < 2.4 is not instrumented with the Resistive Plate Chambers [3] (RPC) originally planned for this region.…”

Upgrade of the CMS muon system with triple-GEM detectors

“…Several large GEM prototypes (∼ 1 × 2 m 2 ) have been developed since 2009 [6,7]. The first large GEM prototype, GE1/1-I, had all components glued together, had spacers and 8 readout sectors.…”

Status report on the CMS forward muon upgrade with large-size triple-GEM detectors

“…However, the standard bakelite RPCs suffer from the strong and increasingly hostile environment in this region and cannot handle the hit rates of a few kHz/cm 2 , that are the ones expected in that region for the HL-LHC phase [3]. The CMS GEM Collaboration has therefore suggested the appealing Gas Electron Multiplier (GEM) technology for upgrading the muon system by proposing to instrument the nonredundant CMS high-η region with triple-GEM detectors [4].…”