Study of the effect of water vapor on a resistive plate chamber with glass electrodes

We studied the effects of water vapor on the efficiencies of resistive plate chambers with glass electrodes, operated in the streamer mode. With moisture in the chamber gas that has freon as a component (water vapor ∼1000 ppm), a decrease in the efficiency (∼20%) has been observed after operating for a period of several weeks to a few months. From our study, the cause of the efficiency decrease was identified as a change on the cathode surface. In addition, a recovery method was found: flushing for 1 day with argon bubbled through water containing ⩾3% ammonia, followed by a few weeks of training with dry gas.