Particle IDentification with the ALICE Time-Of-Flight detector at the LHC

The main physics goal of ALICE (A Large Ion Collider Experiment) is the study of the physics of strongly interacting matter at extreme energy densities, where the formation of a new phase of matter, the Quark-GluonPlasma (QGP), is expected. One of the most important aspect of ALICE is the Particle IDentification (PID) performed by combining different identification techniques. The time measurement with the Time-Of-Flight (TOF) detector, in conjunction with the momentum and track length measured by the tracking detectors is used to calculate the particle mass in the intermediate momentum range from 0.3 up to a few GeV/c. The TOF system covers an area of 141 m(2) and consists of Multi-gap Resistive Plate Chambers (MRPC), that allow excellent performances in terms of intrinsic time resolution (of the order of few tens of ps) and overall efficiency (close to 100%). The ALICE TOF system has shown very stable operation during the first three years of collisions at the LHC, reaching the design goal of 80 ps time resolution. The performance and main physics results will be reported.