In-situ monitoring of the CSC gas gain at CMS

Abstract

The Cathode Strip Chambers (CSCs) are multiwire proportional chambers with cathode strip readout, and they constitute the primary muon tracking device in the endcaps of the CMS (Compact Muon Solenoid) experiment at the Large Hadron Collider (LHC). The CSCs have accumulated a significant radiation dose since the beginning of LHC operations, and it is important to monitor any possible signs of aging and confirm that the detector can sustain the full integrated luminosity expected at the HL-LHC ( 3000 fb−1). Aging effects are assessed by performing in-situ measurements of the gas gain in CSCs as a function of the integrated luminosity. CSC gas gain is studied using muon-induced charge on cathodes using data collected during 2022, corresponding to an integrated luminosity of 39.4 fb−1. The impact of atmospheric pressure and changes in detector settings (HV, gas mixture, etc.) are also taken into account. Based on these CSC gas gain measurments, chamber aging will not be a problem for Run 3. To ensure a definitive assessment for the HL-LHC, an improved control over systematic effects is needed.