The ATLAS RPC detector as a Luminosity monitor

The ATLAS RPC Detector Control System has been mainly used to monitor and safely operate the RPC detector during 2010 and 2011 LHC run. The large number (~3600) of gap currents, individually monitored with nA accuracy, allowed us to study the detector behavior with a growing luminosity and beam currents. A clear linear correlation between the average gap current and the luminosity has been observed over more than four orders of magnitude. This publication will demonstrate how this method has a good potential for improving the accuracy and the stability of the standard luminosity measurements on a long time basis.