Geant4 simulation of a Triple-GEM detector exposed to the CHARM field at CERN

A forward muon detector (ME0) has been proposed for the installation in the CMS endcap muon system in the region 2.0 <; |η| <; 2.8, to increase the muon acceptance. This region is characterized by a very harsh radiation environment, which can reach rates up to few hundreds of kHz/cm 2 . The technology proposed for the ME0 station is Triple-Gas Electron Multiplier (Triple-GEM), which has already been qualified for the operation in the CMS muon system. However an additional set of studies focused on the discharge probability is necessary for the ME0 station, due to the characteristic radiation environment mentioned above. A test was carried out in 2017 at the CERN High energy AcceleRator Mixed (CHARM) facility, with the aim of giving an estimation of the discharge probability of Triple-GEM detectors in a very intense radiation environment, similar to the one in the CMS muon system. A dedicated study with a standalone Geant4 simulation program was performed in order to evaluate the behavior of the detector exposed to the CHARM field. The geometry of the detector has been carefully reproduced, as well as the background field present in the facility. This paper will present the results obtained from the Geant4 simulation, in terms of sensitivity of the detector to the CHARM environment, together with the analysis of the energy deposited in the gas gaps.