Test Beam Study of Gas Electron Multiplier (GEM) Detectors for the Upgrade of CMS Endcap Muon System

Ram Krishna Sharma,Archana Sharma,Ankita Mehta,Marek Michal Gruchala,Md Naimuddin,Priyanka Kumari,Brian Dorney,Jeremie Alexandre Merlin

doi:10.1007/978-3-319-73171-1_40

Abstract

CMS collaboration is planning to upgrade the forward muon chamber during 2019–2020 to cope up with the High Luminosity LHC (HL-LHC) phase. In the HL-LHC phase the forward region, \(|\eta | \ge \) 1.5, of CMS detector will face extremely high particle rates in several tens of kHz/cm\(^2\) and hence it will affect the momentum and longevity of the muon detectors. In concern of above requirement, CMS collaboration is going to install the new large-size, rate-capable Triple Gas Electron Multiplier (GEM) detectors in the forward region of muon system. It will be installed in the GE1/1 region having eta 1.5 \(\le \eta \le \) 2.2 during LS2 of the LHC. For this the full-size CMS GEM prototype detectors were fabricated and tested under test beam at CERN SPS test beam facility. It was tested with two different gas mixtures Ar/CO\(_2\) (70/30) and Ar/CO\(_2\)/CF\(_4\) (40/15/45). In this paper the results of test beam has been summarized based on time resolution and efficiency.

Highlights

CMS[1] is one of the two general-purpose detectors at the CERN, LHC
The first set of Triple Gas Electron Multiplier (GEM) detectors will be installed in the GE1/1 region (1.5 ≤ η ≤ 2.2) of muon endcap during the LS2 of the LHC and the one will be installed in the GE2/1 region (1.6 ≤ η ≤ 2.5), during the LS3
The GEM prototype for CMS detector is known as GE1/1[3], where the letter “G” indicates the GEM detector, the letter “E” indicates that this is muon endcap station, the first “1” indicates that it is part of first muon station encountered by particles from interaction point, and the second “1” indicates that it is first ring of muon chamber going outward in radius from the beam line

Summary

Introduction

The GEM prototype for CMS detector is known as GE1/1[3], where the letter “G” indicates the GEM detector, the letter “E” indicates that this is muon endcap station, the first “1” indicates that it is part of first muon station encountered by particles from interaction point, and the second “1” indicates that it is first ring of muon chamber going outward in radius from the beam line. It is trapezoidal in shape with active area of 990× (220-445)mm. Red sectors are taken with gas Ar/CO2/CF4 (45/15/40) while yellow sector is taken with gas Ar/CO2 (70/30)

Experimental Setup

Result & Discussion