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 ( ∼ 3 – 4 × 10 15 eV ) , the low values of the fluxes require large sensitive areas of a few m 2 . A prototype silicon detector with 64 pads (pixels of 1 cm 2 area) was developed on a 6 ″ wafer as a building block for a large area silicon array. Results on the characterization and performance of the detector are presented.