Improved-RPC for the CMS muon system upgrade for the HL-LHC

TL;DR

The paper discusses the development and testing of improved Resistive Plate Chambers (iRPCs) for the CMS muon system upgrade at the HL-LHC, focusing on enhanced rate capability, timing precision, and durability under high radiation conditions.

Contribution

It introduces new iRPC design and electronics with improved performance metrics for the CMS muon system upgrade at HL-LHC.

Findings

iRPCs demonstrate enhanced rate capability and radiation tolerance.

Electronics achieve timing resolution below 150 ps.

Preliminary performance results are promising for HL-LHC operation.

Abstract

During Phase-2 of the LHC, known as the High Luminosity LHC (HL-LHC), the accelerator will increase its instantaneous luminosity to 5 $\times$ 10$^{34}$ cm$^{-2}$ s$^{-1}$, delivering an integrated luminosity of 3000 fb$^{-1}$ over 10 years of operation starting from 2027. In view of the HL-LHC, the CMS muon system will be upgraded to sustain efficient muon triggering and reconstruction performance. Resistive Plate Chambers (RPCs) serve as dedicated detectors for muon triggering due to their excellent timing resolution, and will extend $|\eta|$ (pseudorapidity) up to a region of 2.4. Before Long Shutdown 3 (LS3), the RE3/1 and RE4/1 stations of the endcap will be equipped with new improved Resistive Plate Chambers (iRPCs) having different design and geometry than the present RPC system. The iRPC geometry configuration improves the detector's rate capability and its ability to survive the harsh background conditions of the HL-LHC. Also, new electronics equipped with excellent timing precision measurements with a resolution of less than 150 ps are developed to readout the RPC detectors from both sides of the strips to allow for good spatial resolution along them. The performance of the iRPC has been studied with gamma radiation at the Gamma Irradiation Facility (GIF++) at CERN. Ongoing longevity studies will help to certify the iRPCs for the HL-LHC running period. The main detector parameters such as the currents, rate and resistivity are regularly monitored as a function of the integrated charge. Preliminary results of the detector performance will be presented.