The Inner Tracking System of the ALICE Experiment at the CERN LHC

The ALICE (A Large Ion Collider Experiment) set-up is the most advanced detection facility for the study of heavy-ion collisions at ultrarelativistic energies, such as those envisaged for the Large Hadron Collider (LHC) at CERN in the near future. Its main goal is the study of the behaviour of matter at high energy densities to search for the transition from the hadronic to the quark-gluon-plasma phase. The ALICE detector is mainly made by a central part, (including the Inner Tracking System, the Time-Projection-Chamber, and a large area particle identification array), which is devoted to the detection of hadronic signals, and a forward part with the muon spectrometer, forward multiplicity detectors and zero-degree calorimeter. Two small areas, single arm detectors (an electromagnetic calorimeter and an array for the identification of high-momentum particles) are also included in the set-up. This contribution is mainly devoted to a report on the present status of development of the Inner Tracking System (ITS). The purpose of the ITS is twofold: to detect the vertices of hyperons and charmed particles, which decay close to the interaction point, and to extend the range of detectable momenta to lower values. To this aim, the ITS has six silicon layers of position sensitive detectors (two pixel layers, two silicon-drift and two silicon-strip layers).