Characterization of sealed (zero gas flow) RPCs under strong irradiation source

Abstract

The phase-out of Hydrofluorocarbons (HFCs), due to their high Global Warming Potential (GWP), affecting the main gas used in Resistive Plate Chambers (RPCs), tetrafluorethane C2H2F4, has created operational difficulties on existing systems and imposes strict restrictions on its use in new systems. A possible solution to the problem is the substitution of this gas by others with a much lower GWP. This approach has attracted the attention of an important part of the community in recent years. But there could be another possibility, which is the construction of sealed chambers, i.e. chambers that do not need a continuous gas flow to operate (in a similar way to Geiger-Muller counters). This possibility would allow continuing to use HFCs or eventually other types of gases that are already banned. It would also greatly simplify the detector, not requiring the complex and expensive gas systems normally used. This simplification could be particularly relevant for outdoor applications, such as in Cosmic Ray experiments. This has motivated a new line of research and development on sealed RPCs: RPCs that do not require a continuous gas flow for their operation. In this work we show the characterization of a sealed RPC plane exposed to an intense radiation source for about one month, with the aim of verifying, in an accelerated way, gas degradation effects that could compromise the operation of the detector. The results show no apparent degradation in any of the parameters studied, namely: efficiency, average charge and streamer probability. The exposure period corresponds, based on the accumulated charge, to approximately four years of natural Cosmic Ray radiation exposure (background signals generated by the detector itself), suggesting the feasibility of the application of this technology in Cosmic Ray experiments for extended periods of time.