Speaker
Description
Resistive Plate Chamber (RPC) detectors are widely used thanks to their excellent time resolution and low production cost. The large RPC systems at the CERN-LHC experiments are operated in avalanche mode thanks to a Freon-based gas mixture containing C2H2F4 (R134a), SF6 and iC4H10. The first two gas will be phased out from production in the near future due to their high global warming potential (GWP). Even if R134a and SF6 will always be available for research purposes, their cost can increase as the interest of industry and marker will decrease. Therefore, the search of new environmental friendly gas mixtures is advisable for reducing GHG emissions, costs as well as to optimize RPC performance and possible aging issues. Several hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) with a global warming potential lower then the C2H2F4 have been studied as possible replacement. New environmental friendly gas mixtures based on these gases with the addition of inert components have been tested on single-gap RPCs by measuring the detector performance in terms of efficiency, streamer probability, induced charge, cluster size and time resolution. Evaluations of the quenching and electronegative capacities of the selected eco-friendly gas candidates have been deduced by comparison of the RPC performance. Operation in streamer mode is easily achievable using HFO-1234ze with the addition of Ar, while the avalanche regime requires further studies since both HFO-1234ze and HFO-1234yf behave very differently from C2H2F4. However, encouraging results of RPC operation in avalanche mode have been obtained with 4 and 5 components gas mixtures.
