Speaker
Description
The improved Resistive Plate Chamber (iRPC) is a newly introduced detector in the CMS Phase-II Upgrade, designed to enhance muon detection efficiency in the forward region under the challenging conditions of the High-Luminosity Large Hadron Collider (HL-LHC). The detector was developed to operate at particle rates of up to 2 kHz/cm², corresponding to the expected background levels with an additional safety factor of three, while maintaining a detection efficiency above 95%. To validate their performance, iRPC detectors were tested at the Gamma Irradiation Facility (GIF++) at the European Organization for Nuclear Research (CERN). GIF++ combines a high-intensity (^{137})Cs gamma source with high-energy muon beams from the Super Proton Synchrotron, providing a controlled irradiation environment that closely reproduces the conditions expected in CMS during HL-LHC operation. The results presented here were collected during the 2025 and 2026 test campaigns. Efficiency measurements were performed for various gamma-source attenuation settings, corresponding to different background radiation levels. The detectors demonstrated excellent performance, maintaining high detection efficiency and stable operation across the full range of irradiation conditions investigated.