RE3/1 & RE4/1 RPC chambers integration in the inner region of the forward muon spectrometer in the CMS experiment

Abstract

The high pseudorapidity (eta) region of the Compact Muon Solenoid (CMS) muon system is covered by Cathode Strip Chambers only and lacks redundant coverage despite the fact that it is a challenging region for muons in terms of backgrounds and momentum resolution. During the annual Year-End Technical Stops 2022 & 2023, two new layers of improved Resistive Plate Chambers (iRPC) will be added, RE3/1 & RE4/1, which will completely cover the region of 1.8 < vertical bar eta vertical bar < 2.4 in the endcap. Thus, the additional new chambers will lead to an increased efficiency for both trigger and offline reconstruction in the difficult region where the background is the highest and the magnetic field is the lowest within the muon system. The extended RPC system will improve the performance and the robustness of the muon trigger. The final design of iRPC chambers and the procedure to integrate and install them in the CMS muon system have been finalized. In this report, the main results demonstrating the implementation and installation of the new iRPC detectors in the CMS muon system at high vertical bar eta vertical bar region will be presented.