CMS RE4 Re-Validation during LS2 and RPC Phase-2 Upgrade

The European Organization for Nuclear Research (CERN) holds the world’s largest and most powerful accelerator, the Large Hadron Collider (LHC), with the aim of acceleration and collision of high energy particles with velocity close to the speed of light, kept at ultra high vacuum and guided by superconducting electromagnets. On par with ATLAS, the Compact Muon Solenoid (CMS) is a large general purpose particle physics detector with the main goal of searching for the Higgs boson, extra dimensions, and dark matter. However, muons detection is one of the most important tasks of CMS, leading us to the tremendous muon trigger system implemented at the CMS experiment. This system is constituted by the Resistive Plate Chambers (RPC), Drift Tubes (DT) and Cathode Strip Chambers (CSC). This report describes the work done under the scope of RPCs. Major tasks include the maintenance of RPC detectors dismounted from CMS during LS2, quality control tests including gas leak testing and reparation of broken components. It describes the work done for quality assurance tests/analysis of HV lines which are to be installed during LS2 for future RPC detectors which will be installed in the coming years, and the work done under the currents and noise studies of RE+4 detectors in order to validate the detectors for re-installation in November 2019.