Study of the timing of discharges in single GEM hole apparatus

The GE1-1 detector is the detector in the CMS, that uses the GEM (Gas electron multiplier) as the main technic to detect the muon. It consists of 5 layers, 3 of GEMS board one drift board and one readout board. The GEMs foil is thin metal-clad polymer foil chemically perforated by a high density of microscopic hole. It uses to exploit electron amplification that occurs within a gas medium inside narrow holes that perforate a thin polyimide foil in a hexagonal pattern. The GEM foil is clad on both sides with thin conductive layers of copper. A voltage of a few hundred volts is applied across the two layers which creates a strong electric field (60-100 kV/cm) inside the holes that cause electron-ion avalanches in the gas. An arrangement of three cascaded GEM foils, commonly known as a “Triple-GEM detector” (see Figure 1.3), allows for modest high voltage and gas amplification across each individual foil to avoid electrical breakdown problems, yet provides a high total charge amplification factor (up to 10^5). When the muon passes through the Drift board, it will ionize the electron in the drift board after that the electron, from the drift board, will be accelerated by the GEM1 and again ionized the gas between the gem after that the electron will be accelerated again by the GEM2 and so on. After the electron ionized the gas between GEM3 and readout board the data will pass through the Readout board to the VFAT3 chips to process the signal. When the electron is accelerated, sometimes it can create the discharge that will damage the detector. This project study relationship between the time different between discharge and protective resistance that use to protect the detector.