The new readout electronics for the HADES RICH detector

A multiwire proportional chamber with CsI photocathode is used for Cherenkov photon detection in the RICH of the dielectron spectrometer HADES at GSI, Darmstadt. Within the ongoing upgrade of the HADES data acquisition system we have developed a new readout chain for the 28500 pads of the photon detector. It is based on frontend amplifier cards utilizing the APV25 chip with operation parameters adopted for gaseous detectors. The analog output data is digitized and further processed by new FPGA controlled ADCM cards with connectivity to the TRB Net. The new electronics is designed for a readout rate of 100kHz (peak) and 20kHz (sustained) for the whole detector system. We present the concept and show first results of full system tests.