AGILE development and silicon detector

In the years 1980s and 1990s, a very fast and important progress on position and energy loss measurements of elementary particles was obtained by the use of Si strip detector in high energy (HE) experiments. The number of strips has been increasing at any improvement of the tracker device. The high number of strip density also pushed the power reduction of the readout electronic amplifiers. The Si tracker became at certain moment a challenging substitute of the classical spark chambers (Fichtel et al. NASA-TM-X-70761, 1995 ; Thompson arXiv:e:0811.0738 , 2008 ), in use for tracking particles in space experiments. In particular in HE γ -strophysics, the photon direction was derived by measuring that of the positron electron pair produced in high Z material interlaid in the planes of the spark chamber. See for instance the EGRET figure in the text. AGILE and GLAST (renamed Fermi after launch) are the most successful examples of the Si revolution.