Speaker
Dr
Marek Michael GRUCHALA
(CERN)
Description
Gas electron multiplier (GEM) technology is being proposed for the forward muon upgrade of the CMS detector for the Phase 2 of the CERN LHC. The proposed prototypes for CMS upgrade, referred to as GE1/1 detectors, are large-area trapezoidal shaped detectors using three GEM-foils arranged in the 3/1/2/1mm gap configuration with 3072 radial readout strips segmented over 24 readout sectors in the (η,φ)-plane. Here η is taken as the pseudorapidity defined as η = -ln(tan(θ/2)); with θ being the polar angle and φ is taken as the azimuthal angle. The GE1/1 system will be located on the CMS endcap; it will add redundancy and improved trigger momentum resolution, in the 1.6 < |η| < 2.2 range, to the CMS forward muon system. The charged particle, muons and mixed hadron beams, detection performance of GE1/1 detectors is studied at beam lines supplied by the CERN Super Proton Synchrotron. The experimental setup consists of multiple small triple-GEM detectors, featuring two-dimensional Cartesian readout strips for track reconstruction, and between three and five, depending on the run period, large GE1/1 detector prototypes. Detection efficiencies and time response measurements are made as a function of the gain of the GE1/1 detectors with both Ar:CO2 (70:30) and Ar:CO2:CF4 (45:15:40) gas mixtures. For the latter the measurements are also repeated as a function of the Cartesian strip pitch. The measured detector performance properties are found to be suitable for the CMS forward muon upgrade.
Primary author
Prof.
Gavin Davies
(Imperial College London)
