Sealed (zero gas flow) RPCs — a new operational paradigm for gaseous detectors

Resistive Plate Chambers (RPCs) are gaseous detectors widely used in High Energy Physics due to their excellent timing performance, high efficiency, scalability, and affordability. However, their operation relies on gas mixtures based on hydrofluorocarbons (HFCs), whose high Global Warming Potential and progressive phase-out under current environmental regulations pose significant challenges for the long-term sustainability of RPC technology. In this work, we investigate a conceptually different approach, as an alternative to eco gas-mixture substitution strategies, based on sealed RPCs, in which the detector is filled with standard gas during assembly and subsequently hermetically sealed, allowing operation without any external gas supply. This approach drastically reduces gas consumption, eliminates the need for complex gas systems, and offers a potential solution compatible with both environmental constraints and high-performance operation. Two sealed RPC configurations, with active areas of approximately 0.1 m 2 and 1 m 2 , have been developed and characterized using atmospheric cosmic muons. The 0.1 m 2 module demonstrates stable operation over an extended period of nearly two continuous years, with an average efficiency of about 98% and low streamer probability. The 1 m 2 prototype exhibits a comparable initial response, although limitations related to mechanical stability are observed. These results demonstrate the feasibility of sealed RPC technology for trigger applications and highlight its potential as a robust, cost-effective, and environmentally sustainable alternative for future gaseous detector systems.