ATLAS RPC time-of-flight performance

We show that RPC time resolution for proton-proton collisions at sqrt(s) = 7 TeV with data recorded by the ATLAS detector in 2011 at LHC is about the expected one taking into account the intrinsic time resolution of a 2-mm thick RPC in avalanche mode, digitization error, time walk, and electronic noise. The off-line timing calibration procedure and reconstruction algorithm needed to achieve the ultimate timing resolution are explained in detail. Very simple algorithms were used for off-line time calibration allowing for a possible on-line implementation in future up-grade scenarios. The achieved time resolution can be used to suppress background hits at high luminosity and measure velocity to search for exotic slow particle from Physics beyond the Standard Model.