Étude de la production de photons isolés en collisions proton-proton avec le calorimètre EMCal de l'expérience ALICE au LHC

Prompt photons produced in the hard initial parton-parton scatterings in high-energy proton-proton collisions – such as those at the CERN Large Hadron Collider (LHC) – are an excellent tool to study perturbative Quantum Chromodynamics. In particular, high transverse momentum(pT) photons provide crucial information on the parton distribution functions (PDFs) of the proton. Experimentally, in order to measure prompt photons, one needs first to get rid of various other photon sources, especially those from the large background due to pi0 decays. The electromagnetic calorimeter (EMCAL) of the ALICE (A Large Ion Collider Experiment) experiment at the LHC covers the central rapidities and provides improved capabilities to measure high-pT photons in ALICE.We present here studies of photon production in high-energy proton-proton collisions, as well as a complete analysis of their measurement with the EMCAL detector, giving details in particular on the methods developped to separate them from the pi0 decay photons with the help of isolation cuts.