A Large Area Silicon Pixel Array for the Identification of Relativistic Nuclei in Cosmic Ray Experiments

Space-based and balloon-borne experiments, designed for direct measurements of the elemental composition and energy spectra of charged cosmic rays, require an unambiguous identification of the incoming particle. This task can be carried out via an accurate determination of the charge of the primary nucleus by dE/dx measurements with pixelated silicon detectors. At energies close to the knee ð_324 _ 1015 eVÞ, the low values of the fluxes require large sensitive areas of a few m2. A prototype silicon detector with 64 pads (pixels of 1 cm2 area) was developed on a 600 wafer as a building block for a large area silicon array. Results on the characterization and performance of the detector are presented.