ALICE, A Large Ion Collider Experiment, is conceived to study the physics of strongly interacting
matter and the properties of the Quark–Gluon Plasma produced in ultra-relativistic heavy-ion
collisions at the CERN LHC.
The innermost detector of ALICE is the Inner Tracking System (ITS) which plays the essential
role of primary and secondary vertex reconstruction. It is used for particle tracking and identification
and contributes to the first level trigger. The ITS covers the pseudo-rapidity range |ƞ| < 0:9
and consists of six cylindrical layers of silicon detectors placed coaxially around the beam pipe.
Three different technologies were selected to equip the ITS: pixel detectors for the two inner
layers, drift detectors for the two central layers and strip detectors for the outer layers.
In this report the three detectors constituting the ITS are briefly described, the operational experience
during RUN2 is summarised with a focus on the performance of the detector compared to
RUN1 and on the interventions done during the long technical stop at the end of 2015.