Environmental Background Hit Rate on GE1/1 in the 2018 Slice Test

The CMS Collaboration has decided to add new detectors using GEM technology at Stations 0, 1 and 2 of the endcap region of the CMS muon system for the upcoming HL-LHC runs. These GEM detectors will be operated in a harsh radiation environment. Thus a measurement of the environmental background hit rate is crucial. CMS installed five GEM super-chambers at Station 1 (GE1/1) in Run-2 and gained valuable operational experience (the Slice Test). The first measurement of the background hit rate at GE1/1 at an instantaneous luminosity of up to \(2\times10^{34} cm^{-2}s^{-1}\) is presented.