Longevity studies for the CMS-RPC system

In the next decades, the Large Hadron Collider (LHC) will run at very high luminosity (HL-LHC) 5$\times10^{34}$ cm$^{-2}$s$^{-1}$, factor five more than the nominal LHC luminosity. During this period the CMS RPC system will be subjected to high background rates which could affect the performance by inducing aging effects. A dedicated longevity program to qualify the present RPC system for the HL-LHC running period is ongoing. At the CERN Gamma Irradiation Facility (GIF++) four spare RPC detectors are exposed to an intense gamma radiation for a period corresponding to the expected integrated charge at HL-LHC. The main detector parameters are under monitoring as a function of the integrated charge and the performance studied with a muon beam. Preliminary results of the study after having collected $\approx$ 34\% of the expected integrated charge will be presented.