Coupling Muon Solenoid (CMS) Gas Electron Multiplier (GEM) & Voltage Divider Project

The European Organization for Nuclear Research (CERN) is home to the Large Hadron Collider (LHC) which is a 27km ultra-high-vacuum ring that is 100 meters underground. The LHC uses a network of superconducting electromagnets and an electric field to accelerate two opposing proton beams to near the speed of light. To further investigate the laws of physics and convert the large energy into fundamental particle mass, the opposing proton beams collide. The LHC has increased it's luminosity, essentially increasing the number of particles produced following a collision of two proton bunch crossings; the increase of luminosity requires improved momentum resolution. The Large Hadron Collider has four collision sites: ATLAS, ALICE, CMS and LHCb. The Compact Muon Solenoid is a muon detector that records new data every 25 ns. To upgrade the CMS, the new Gas Electron Multiplier modules GE1/1, GE2/1 and ME0 are developed and installed. The GEM detectors amplify the electrons that are a product of the muon ionization, thus making it easier to detect the beam by differentiating it from noise. The amplification occurs as a result of the capacitance of the GEM foils. Gas Electron Multiplier foils are two copper sheets with dielectric kapton in between them. GEM foils have 70 micron holes with 140 micron distribution. The potential difference introduced to the foils induces an electric field. With three GEM foils, the amplification of the electrons reaches a factor of 8000. The distance between the three GEM foils is (3,1,2,1)mm from Drift to GEM1, GEM2, GEM3 to Readout respectively. The material of the GEM modules is meant to withstand the high radiation of the test beam area. This upgrade will improve muon detection by improving spatial resolution and granularity. The ME0 will also improve PT resolution (transverse momentum) while simultaneously reducing neutron background noise. To ensure that the modules are of acceptable standards, Quality Control tests are done. Quality Control 1 and 2 involve checking on the GEM foil's health, while Quality Control 3 and 4 check the module's Gas Leakage as well as the Intrinsic Noise respectively.