Exploring the nuclear phase diagram using hard and electromagnetic probes

The project will be focussed on the use of high transverse momentum electromagnetic probes (photons and dileptons) as tools for investigating the early stages of a heavy-ion collision. High-pT hadrons, charged and neutral, are created during the initi al partonic collisions. Through their energy loss in a deconfined medium, they probe the properties of the QGP. Neutral pions can be reconstructed from their photonic decays. Direct photons and dileptons carry unaltered information from the early s tages of the reaction. Heavy quarkonia can be reconstructed through their dileptonic decay channels. Their yields are strongly influenced by the surrounding medium. The LHC accelerator at CERN will start physics runs in 2007, with p+p collisions at a center-of-mass energy of 14 TeV, followed by Pb+Pb collisions at 5.5 TeV per nucleon pair. The PHOS photon detector in ALICE is designed to measure direct photons and neutral hadrons with diphotonic decays. The combination of the ALICE Time Projection C hamber, Transition Radiation Detector and Inner Tracking System with the High Level Trigger allows fast selection of high-pT dilepton candidates, including direct dileptons, heavy quarkonium decays and e+e-photon conversions. The project will involve t he measurements of transverse momentum spectra of neutral pions as a function of system size, in order to probe the QGP opacity. Yields of heavy quarkonia will be determined. Extraction of direct photons and dileptons will be attempted. The fir st few years of the project will involve development and optimization of reconstruction algorithms needed for the measurements, and also detector tests. The last part of the project period will be dedicated to the physics analysis of the first ALICE data. Education of master, doctoral and postdoctoral candidates is an integral part of the project.