A Model for RPC detectors operating at high rate

We present a simple model to describe the behavior of Resistive Plate Chambers (RPC) exposed to a high particle flux. We show that the RPC current, I, saturates at large flux values and we explain why the dependence of I on the applied voltage V-0 is essentially linear. We show that in the saturated regime the current is controlled by the value of the bulk electrode resitivity, rho, which is directly related to the performance of the detector at high particle rates. Measuring the I - V-0 curve under these conditions offers a simple and direct method to obtain rho and to monitor its possible variations