The upgrade of the CMS muon system for the High Luminosity LHC

Abstract

The muon system of the CMS experiment is expected to upgrade all of its subdetectors for the Phase-2 of the Large Hadron Collider (LHC) that will begin in 2029. The upgrade plans for drift tubes (DTs), cathode strip chambers (CSCs) and resistive place chambers (RPCs) include a new electronics for better performance in high background rate conditions and to sustain the large radiation dose delivered by the high-luminosity LHC (HL-LHC). Two new RPC stations will also be installed to complement CSCs in the forward region $1.8 < |\eta| < 2.4$, while three stations of triple-GEM (gas electron multiplier) detectors will complement CSCs in the region $1.5 < |\eta| < 2.4$ and extend the CMS muon system coverage in the very forward pseudorapidity region up to $|\eta| = 2.8$. We present the goals and status of the CMS muon system upgrade including the performance of the early Phase-2 upgrades demonstrated in Run 3 with proton-proton collisions, the performance validation of the new detectors in test beams and the mass production status of the new stations.