CMS CSC Longevity Study

Cathode Strip Chambers (CSCs) are used in the muon system of the CMS experiment at LHC. There are four muon stations on both endcaps consisting of 540 CSCs operating with $$40\%\textrm{Ar}+50\%\textrm{CO}_{2}+10\%\textrm{CF}_{4}$$ gas mixture. The chamber longevity study is particularly important in anticipation of the future LHC upgrade into High Luminosity LHC (HL-LHC) and the scheduled upgrade of the CMS detector. CSC longevity is studied with two CMS chambers: ME1/1 and ME2/1 at the Gamma Irradiation Facility (GIF++, CERN). The tests did not show any degradation in the chamber’s performance. The study of the reduction of, or possible replacement of, the CF $${}_{4}$$ in the working gas mixture is also ongoing, including longevity studies with small CSC prototypes.