• analisi dati
• CALET
• raggi cosmici
• rivelatori

The work described in this thesis has been carried out in the framework of the Italian participation in the CALET space mission (CALorimetric Electron Telecope) that is currently in preparation for a launch to the International Space Station (ISS). The CALET experiment has been designed to perform accurate measurements of cosmic-ray radiation aboard the ISS for at least 5 years. Its main scientific goals are the measurement of the inclusive spectrum of electrons and positrons, the observations of gamma-ray sources, the search for dark matter signatures and the measurement of nuclei spectra. The CHarge Detector (CHD) consisting of two layers of scintillating paddles is part of the CALET instrument and its prototype was tested with an ion beam of 30 GeV/n kinetic energy at CERN SPS in January-February 2013. The analysis of the data collected during the beam test is presented in this thesis and the CHD capability to perform charge identification is assessed. The measurement of cosmic-ray relative abundances is one of the main physics goals of CALET and its aim is to be able to discriminate among different theoretical cosmic-ray propagation models.

In the first chapter, an introduction to cosmic-ray physics is presented and cosmic-ray propagation and acceleration are described; a section about electrons in the cosmic-ray flux is also present, given their importance as the main scientific goal of the CALET observations on the ISS.

The second chapter focuses both on the CALET instrument and on its main scientific goals.

In the third chapter, the basic principles of charge detection are described. As the beam test equipment included a dedicated Beam Tracker built by the Italian group and designed to tag each nuclear species (up to Z=26 and above) in the SPS beam of mixed fragments from primary Pb projectiles, the working principles of silicon pixel and silicon strip detectors are briefly reviewed in this chapter.

The fourth chapter describes the beam test instrumentation and how it was arranged during the data taking operations.

In the fifth chapter the charge tagging procedure is described and the data analysis of the Beam Tracker data is presented.

In the sixth chapter the scintillating CHarge Detector data analysis is described: charge resolution for neighbouring ions is estimated. The light saturation effect for high Z nuclei within the plastic scintillator is also measured and compared with a halo model of local energy deposit and delta-ray propagation.