A silicon array for cosmic-ray particle identification in space

A new generation of space experiments with very large geometric factors (of the order of 3 - 4 m2sr) are being designed to perform precision studies of the elemental composition of Very HighEnergy (VHE) cosmic nuclei and of their spectral features. In the current concept of the Gamma400 experiment, the charge identification of the incoming particle is performed by a two-layered array of pixelated silicon sensors. Given the orbital parameters of the mission, the isotropic distribution of the incoming cosmic rays can be sampled on the 4 lateral sides of the instrument. The conceptual design of the array, covering a seamless sensitive area of the order of 1 m2, will be presented together with results obtained with reduced-scale prototypes at relativistic ion beams.