CaloCube: A new-concept calorimeter for the detection of high-energy cosmic rays in space

The direct observation of high-energy cosmic rays, up to the PeV region, will increasingly rely on highly performingcalorimeters, and the physics performance will be primarily determined by their geometrical acceptance and energyresolution. Thus, it is extremely important to optimize their geometrical design, granularity, and absorption depth,with respect to the total mass of the apparatus, which is among the most important constraints for a space mission.Calocube is a homogeneous calorimeter whose basic geometry is cubic and isotropic, so as to detect particlesarriving from every direction in space, thus maximizing the acceptance; granularity is obtained by filling the cubicvolume with small cubic scintillating crystals. This design forms the basis of a three-year R &D activity which hasbeen approved and financed by INFN. A comparative study of different scintillating materials has been performed.Optimal values for the size of the crystals and spacing among them have been studied. Different geometries, besidesthe cubic one, and the possibility to implement dual-readout techniques have been investigated. A prototype,instrumented with CsI(Tl) cubic crystals, has been constructed and tested with particle beams. An overview of theobtained results will be presented and the perspectives for future space experiments will be discussed.