'Study of diphoton final states with the ATLAS detector at the LHC : differential cross-section measurement, discovery of a new resonance in the search of the Standard Model Higgs and measurement of its properties'

These thesis will be concentrated on the analysis of events involving two photons in the final state. The activity will evolve with time and will cover different aspects: understanding of the detector response, participation to the data taking, physics analysis and search for physics behind the Standard Model