Systematic study of gas mixtures for timing RPCs

RPC timing properties are mainly determined by the maximum ionization rate that can be sustained while keeping the streamer fraction at modest values. The last characteristic, resilience to streamers, cannot be fully calculated, calling for an experimental approach. In this work we systematically study the influence of a range of gas mixtures on the performance (background counting rate, efficiency, time resolution and charge spectrum) of timing RPCs, using cosmic rays as ionizing particles.