Dr Nicola Mori (INFN Florence)
Calorimetry plays an essential role in experiments for observing very high energy gamma and cosmic rays in space. Geometrical dimensions and mass of the calorimeter are the main limiting factors. The available mass depends on the design of the detector and the total available mass of the payload. It is therefore important to optimize the geometrical acceptance of the calorimeter for rare events, its granularity for the identification of the arriving particle and its depth for the energy measurement. We studied the design of a calorimeter that could simultaneously optimize these characteristics assuming a limit mass of about 1.6 t. The best choice resulted to be a homogeneous calorimeter made by cesium iodide (CsI), as the best compromise between the radiation and interaction lengths of the material. The most convenient geometry is cubic and isotropic to detect particles arriving from any direction in space, thus maximizing the acceptance; granularity is obtained by filling the cubic volume with small cubic CsI crystal. The total depth in any direction is very high both in radiation and interaction lengths, and allows for electromagnetic particle identification better than 10-5 and optimal energy measurement. Side of the crystal and needed space between them for managing their mechanical support and external electrical connections have been studied. A prototype has been realized and preliminary tests on high energy electron and proton beams are reported.
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