Studies on RPC detectors operated with environmentally friendly gas mixtures in LHC-like conditions

Abstract

Resistive Plate Chambers (RPC) are largely employed at CERN LHC experiments thanks to their excellent trigger and timing performances. High Pressure Laminates (HPL) RPCs are operated with a gas mixture made of about 95% of C2H2F4, 5% of i-C4H10 and 0.3% of SF6. Both C2H2F4 and SF6 are known to be Greenhouse Gases (GHG), with a global warming potential of 1430 and 22800 respectively. Due to leaks at the detector level, RPCs accounted for about 87% of total GHG emissions from particle detectors at CERN during LHC Run 2. CERN has elaborated several strategies to reduce its GHG emissions and align with the European regulation on fluorinated gases. One strategy consists in the study of alternatives gases for particle detectors, with a particular focus on alternatives to R-134a and SF6. An experimental setup was designed to study RPC performances with eco-friendly gas mixture first with cosmic muons, where several gas mixtures could be tested. Few gas mixtures were then selected and a dedicated setup was installed at the Gamma Irradiation Facility of CERN to characterize detector performance with LHC-like background radiation and muon beam. Results with RPCs operated with lower GWP gas mixtures are presented in this work.