Heavy Ion Collisions at the LHC; the ALICE Experiment

ALICE (A Large Ion Collider Experiment) is a detector designed to exploit the physics potential of nucleus-nucleus interactions at the LHC. Being a general purpose experiment, it will allow a comprehensive study of hadrons, electrons, muons and photons, produced in the collision of heavy nuclei, up to the highest particle multiplicities anticipated (dNch/dy=8000). In addition to heavy systems (Pb-Pb), we will study collisions at smaller energy densities by using lower-mass ions (e.g. A~40). Reference data will be obtained from pp and p-nucleus collisions. The central part of ALICE covers $|\eta| < 0.9$, and consists of an inner tracker (ITS), a TPC and a particle identification array (PID), all embedded in a large magnet with a weak solenoidal field. The experiment is completed by two small area spectrometers in the barrel region (an electromagnetic calorimeter, PHOS, and a high momentum PID detector, HMPID), a forward muon spectrometer (2 degrees to 9.5 degrees) and a ZDC.