First CMS upgraded muon detectors events

At the CMS experiment, many subsystems are being upgraded during the Long Shutdown 2 (LS2, 2019-2021), including the muon detectors, in order to cope with the future high-luminosity LHC. The experiment needs to quickly identify high momentum muons because these are a key characteristic signature of new physics processes. During the long shutdown in 2018-2022, most parts of the muon system and their readout electronics have been upgraded to be able to successfully detect the increased muon rates during future LHC runs. To achieve that, novel gaseous detector technologies are being tested in 2021 already, capable of handling high particle rates: the Gas Electron Multiplier (GEM) and improved Resistive Plate Chambers (iRPC). The first GEM station (GE1/1) has already been produced and installed in the experiment In October/November 2021 these detectors were first exposed to low-energy test collisions during the LHC pilot beam tests.