ALICE detector at LHC

ALICE (A Large Ion Collider Experiment) is a dedicated detector designed to exploit the unique physics opportunities which will be offered by nucleus-nucleus collisions at the LHC. ALICE has been conceived as a general-purpose detector, in which hadrons, electrons and photons produced in the interaction can be measured and identified. The detector is designed to cope with the highest particle densities anticipated in Pb-Pb interactions at the LHC (8000 per unit of rapidity). An acceptance of about two units of rapidity has been chosen, which has been calculated to be sufficient to define most of the variables sensitive to the onset of a phase transition to a quark-gluon plasma. The baseline design of ALICE consists of a central (|η|&le0.9) detector covering the full azimuth, complemented by a multiplicity detector covering the forward rapidity region (up to η = 4.8) and a zero degree calorimeter. The central detector will be embedded in large magnet with a weak field of 0.2 T, and will consist of a high-resolution inner tracking system, a cylindrical TPC, a particle identification array (time of flight or ring imaging Cherenkov detectors) and a single-arm electromagnetic calorimeter. Possible upgrades to this baseline design are currently under study, including a muon identification system and a large acceptance electromagnetic calorimeter.