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Abstract
| We present the final results of an extensive aging test, performed at the CERN Gamma Irradiation Facility on two bakelite Resistive Plate Chambers (RPC) detectors. With a method based on a model describing the behaviour of an RPC under high particle flux conditions, we have periodically measured the electrode resistivity rho of the two RPC prototypes over 3 years. We observed a large spontaneous increase of rho with time, from the initial value of about 10**1**0 Omega cm to more than 200 multiplied by 10**1**0 Omega cm. A corresponding degradation of the RPC rate capabilities, from more than 3 kHz/cm**2 to less than 200 Hz/cm**2, was observed; the reversibility of the process, using a humid gas mixture, has also been studied. We also present a study of the effects of humidity on the bakelite resistivity using two 10 multiplied by 10 cm**2 bakelite samples. |