Silicon detectors in space for γγ-ray astroparticle physics

Silicon detectors are the core of two instruments that has been constructed for the study of the γγ-ray sky in the pair production regime (above 10–20 MeV). One, AGILE, has been launched on the 23 of April while the other, GLAST, will be launched in the middle of 2008. Here we will describe the advantage in respect to the previous techniques and the performances of these detectors.