The strong interaction theory, Quantum Chromodynamic (QCD), predicts a new phase of nuclearmatter at very high temperature and/or very high density. This state is composed of deconfinedquarks and gluons known as the quark-gluon plasma (QGP). The measurement of its compositionand properties is a challenge for the nuclear physics of the 21st century and should lead to a betterunderstanding of the fundamental symetries and mechanisms related to the quarks confinement insidehadrons and the strong interaction generally.The Large Hadron Collider (LHC) accelerator at CERN (European Organization for NuclearResearch) allows to reach the thermodynamic conditions required to create the quark-gluon plasmausing ultra-relativistic heavy ion collisions (Pb). The ALICE experiment (A Large Ion ColliderExperiment) allows to access several probes to characterize the QGP through particles reconstructionand. Among these probes, high energy parton energy loss is used to access medium characteristicssuch as density or temperature. Parton energy loss is estimated from the modification of the energydistribution of hadrons produced by fragmentation.This thesis is dedicated to the photon-hadron correlations analysis in order to study the modificationof the parton fragmentation due to the quark-gluon plasma. First part of this thesis is devotedto the characterization of the electromagnetic calorimeter (EMCal), the central detector for energymeasurement and photon identification. The second part is dedicated to the photon-hadron correlationmeasurement, for the 7 TeV proton-proton collisions and 2.76 TeV Lead-Lead collisions. Animportant work has been done to improve the prompt photon identification, one of the key point ofthis analysis.
