The thermal and vibrational tests of the AGILE silicon tracker

AGILE (Light Imager for Gamma-ray Astrophysics) is a satellite for simultaneous observation of gamma rays in the energy range 30 MeV-50 GeV and X-rays in the range 15-45 keV. The main instrument of the scientific payload is a silicon-tungsten tracker with 37000 readout channels distributed in 12 planes with two views of silicon detectors each. The planes are organized in 13 trays, each of them made by a 14 mm core of Al honeycomb covered on both sides by a 0.5 mm fiber layer. On each side of the tray, 16 single-sided, AC-coupled, 410 μm thick, 9.5×9.5 cm² silicon strip detectors are assembled in 4 ladders of 4 detectors. In the first 10 trays, a tungsten layer 245 μm thick (corresponding to 0.07 radiation lengths) is positioned above the silicon layer. The strips of the two sides are orthogonal in order to obtain the x-y information of the passage of the electron-positron pair created by the photon. The validation of the tray mechanical structure has required both thermal, thermo-vacuum and vibrational tests in order to qualify from a space point of view the materials, the adhesives and the assembly procedures. The tests have been performed on single trays mounted with silicon detectors and on the simplified engineering model of the flight payload. The detectors have been tested at each step with cosmic rays and have acquired data throughout the thermal cycles. The assembly procedures and both vibrational and thermal tests will be described in detail.