Speakers
Description
Resistive Plate Chambers (RPCs) traditionally operate with a gas mixture based on C$_2$H$_2$F$_4$ (TFE) and SF$_6$, both high-GWP greenhouse gases facing growing regulatory and supply restrictions. C$_3$H$_2$F$_4$ (F-HFO) diluted with CO$_2$ has been proposed as a lower-GWP substitute for TFE, while its chlorinated variant, C$_3$H$_2$ClF$_3$ (Cl-HFO), has separately been explored as a streamer suppressor replacing SF$_6$. However, most studied mixtures still retain either TFE or SF$_6$. This work targets mixtures free of both.
We present a preliminary Monte Carlo study, based on Geant4 and Garfield++ simulations, of two CO$_2$-based mixture families. The first revisits CO$_2$/F-HFO/i-C$_4$H$_{10}$/Cl-HFO, exploring new CO$_2$:F-HFO ratios not yet covered in the literature. The second proposes an untested quaternary mixture, Ar/CO$_2$/N$_2$/Cl-HFO, replacing the fluorinated fraction with an Ar-based matrix. In both cases, Cl-HFO is kept in minority concentration as the streamer-suppressing component replacing SF$_6$.
For both mixtures, Townsend and attachment coefficients, gas gain, drift velocity, efficiency and streamer probability are computed versus applied field and compared to the standard mixture. Results address operating voltage shift, plateau width, and whether Cl-HFO sustains streamer suppression without SF$_6$ in a non-fluorinated base, framing open questions for future experimental validation.