A study of gas contaminants and interaction with materials in RPC closed   loop systems
  Resistive Plate Counters (RPC) detectors at the Large Hadron Collider (LHC) experiments use gas recirculation systems to cope with large gas mixture volumes and costs. In this paper a long-term systematic study about gas purifiers, gas contaminants and detector performance is discussed. The study aims at measuring the lifetime of purifiers with unused and used cartridge material along with contaminants release in the gas system. During the data-taking the response of several RPC double-gap detectors was monitored in order to characterize the correlation between dark currents, filter status and gas contaminants. 
S. Colafranceschi, R. Aurilio, L. Benussi, S. Bianco, L. Passamonti,   D. Piccolo, D. Pierluigi, A. Russo, M. Ferrini, T. Gr...
physics.ins-det hep-ex