Study of the performance and aging of RPCs

The study of resistive plate chambers (RPCs) carried out at the Gran Sasso National Laboratory (LNGS) over many years is presented. The performance of glass resistive plate chamber operated in avalanche mode has been studied by varying the particle rate and the temperature. The rate capability strongly improves with temperature, due to the lowering of the volume resistivity of glass electrodes. The glass RPC has also been studied in streamer mode, with several gas mixtures composed by argon, C/sub 2/H/sub 2/F/sub 4/; IsoC/sub 4/H/sub 10/ and SF/sub 6/: a small percentage of SF6 strongly reduces the streamer size, it allows an isobutane percentage well below the flammability limit and it improves the time resolution of the detector. Finally, a set of measurements has been carried out to assess the RPC aging under different operational conditions.