Detector physics of resistive plate chambers

Multigap resistive plate chambers with 0.3 mm gas gaps operated in avalanche mode at atmospheric pressure have reached timing accuracies below 50 ps /spl sigma/ with efficiencies above 99%. The avalanches in high homogeneous electric fields of 100 kV/cm are strongly influenced by space charge effects which are the main topic of this report. A Monte Carlo simulation applying well known detector physics processes reproduces accurately the measured efficiencies, time resolutions and charge spectra of these RPCs. The detailed simulation of avalanche saturation explains; the small observed charges and the linear increase of average charges with high voltage.