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

TL;DR

This paper presents test beam results of a large-area GEM detector prototype designed for the CMS muon system upgrade, demonstrating its potential for improved tracking and triggering in high-luminosity conditions.

Contribution

It reports the design, construction, and performance evaluation of the largest full-size Triple-GEM detector for CMS, addressing technological challenges for high-luminosity LHC environments.

Findings

High efficiency achieved in test beams

Good spatial resolution demonstrated

Fast timing performance confirmed

Abstract

Gas Electron Multipliers (GEM) are an interesting technology under consideration for the future upgrade of the forward region of the CMS muon system, specifically in the $1.6<| \eta |<2.4$ endcap region. With a sufficiently fine segmentation GEMs can provide precision tracking as well as fast trigger information. The main objective is to contribute to the improvement of the CMS muon trigger. The construction of large-area GEM detectors is challenging both from the technological and production aspects. In view of the CMS upgrade we have designed and built the largest full-size Triple-GEM muon detector, which is able to meet the stringent requirements given the hostile environment at the high-luminosity LHC. Measurements were performed during several test beam campaigns at the CERN SPS in 2010 and 2011. The main issues under study are efficiency, spatial resolution and timing performance with different inter-electrode gap configurations and gas mixtures. In this paper results of the performance of the prototypes at the beam tests will be discussed.