The Standard Model And The Higgs Boson.- Supersymmetry.- The Large Hadron Collider.- The ATLAS Detector.- Physics Objects Reconstruction With The ATLAS Detector.- Electron And Photon Energy Calibration.- Photon Identification And Isolation.- Measurement Of The Higgs Boson Mass In The H → Γγ Channel.- Search For Superymmetry In Γγ + Etmiss final State.- Conclusion.