ALICE ITS operational experience

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 identifica- tion and contributes to the first level trigger. The ITS covers the pseudo-rapidity range | η | < 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 expe- rience 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.