In May 2011 AMS-02 detector has been successfully installed on the International
Space Station (ISS), where it will take data on cosmic radiation from 1 to 1000 GeV
for at least 10 years.
Among all scientific objectives of the experiment, one of the most important is
the search for Dark Matter (DM), which constitutes ∼ 80% of the Universe mass,
but its nature is still unknown. A DM signal can be identified by studying the
combined fluxes of positrons, photons, antiprotons and antideuterium. Thanks to
its high acceptance and its performances, AMS-02 detector can extend and expand
primary cosmic ray physics search to a new energy range with high accuracy.
A key role for these measurements, in particular for electromagnetic channels, is
played by ECAL calorimeter. This subdetector has been developed to measure γ, e−
and e+ energy with an accuracy of few %. Thanks to its 3D shower reconstruction
imaging capabilities, it also has a high separation power between electromagnetic and
hadronic showers (e/p rejection), essential to eliminate proton background (∼ 10^4 )
in positron channel. Finally, it provides the trigger on photons which do not interact in the upper part of the detector (about 72% of the ones in ECAL geometrical
acceptance).
In Chapter 1 of this thesis, cosmic ray physics is introduced with details on Big
Bang cosmology and the DM problem. Then, a summary of direct and in particular
indirect searches for DM signature is presented.
In Chapter 2 and 3 AMS-02 detector is presented with an overview of each subdetector features and performances. ECAL electromagnetic calorimeter is described
in detail.
Chapter 4 describes an in-flight calibration method, which has been developed
and tested on August 2010 Test Beam data, with its application performances on
ground and on in-flight data.
In Chapter 5, the calorimeter capabilities have been used to develop e± identification algorithms, using both ECAL standalone and also tracker momentum measurements. The definition of algorithms, training and testing processes, data-MC
comparisons and proton rejection spectrum are described
