Performance of the AMS02 Electromagnetic Calorimeter in space

The Alpha Magnetic Spectrometer (AMS-02) is a general purpose high energy particle detector which was successfully deployed on the International Space Station (ISS) on May 19, 2011 to conduct a long duration mission of fundamental physics research in space. After one year of operation, AMS-02 has collected more than 17 billions of events. The main scientific goals of the experiment are the searches for antimatter and dark matter, the high precision measurement of charged cosmic ray spectra and fluxes and the study of gamma rays, in the GeV to TeV energy range. In AMS-02, the Electromagnetic Calorimeter (ECAL) is required to measure e+, e- and gamma spectra and to discriminate electromagnetic showers from hadronic cascades. To fulfill these requirements the ECAL is based on a lead/scintillating fiber sandwich, providing a 3D imaging reconstruction of the showers. AMS-02 has been tested during Summer 2010 in a test beam at CERN, using 10 to 250 GeV electron and positron beams and proton beam at 400 GeV. After a summary of the AMS02 performance in space, results on the measurements of ECAL parameters and performance will be reviewed.