The Alpha Magnetic Spectrometer AMS-02 is a particle physics experiment designed to operate for a long time in space. It was installed on the International Space Station ISS in May 2011 and its purpose is to obtain accurate and high-statistics measurements of cosmic rays spectra and composition up to TeV energies, searching for primordial Anti-Matter and probing the nature of Dark Matter. AMS-02 is mainly conceived as a charged-particle detector, but the unique features of its electromagnetic calorimeter also allow the identification of γ-rays. ECAL has an excellent energy resolution and a high granularity that makes possible the reconstruction of the direction of the incoming particle with an unprecedent angular resolution for a calorime...