1. The AMS-02 detector is based on a large acceptance (~0.5 m²sr) and high sensitivity spectrometer composed by a super-conducting magnet (0.8 T), cooled by evaporating liquid helium, and a silicon tracking device, achieving a spatial resolution of ~ 10 µm in the bending direction and ~30 µm in the orthogonal direction, which will provide a rigidity range for charged particles up to few TV. The measurement of energy deposition in silicon will also allow nuclei identification. The design of the Silicon Tracker has been guided by the strict conditions of space, such as the mechanical stress during the launch, large temperature range, limited electrical power available and weight. In order to remove the heat dissipation generated inside the magnet by the front-end electronics the Tracker has a dedicated Thermal Control System based on a mechanically pumped two-phased loop operating with carbon dioxide. The AMS-02 Tracker The silicon sensors will be arranged in 192 ladders, which will be installed in eight layers of ~1 m² each on five planes of an ultra-light support structure. The AMS-02 Silicon Tracker will be built with close 2500 double sided silicon microstrip sensors, which allow to measure two coordinates with a single detector, reducing thus the material budget. AMS-02 silicon sensors characteristics Dimensions 7.2 cm × 4.1 cm Thickness ~300 µm Active width p-side ~70.5 mm Strip pitch p-side 27.5 µm Num. of p-strips 2568 Readout pitch p-side 110 µm Num. of p-side readout strips 640 Active width n-side ~39.8 mm Strip pitch n-side 104 µm Num. of n-strips 384 Readout pitch n-side 208 µm Num. of n-side readout strips 192 The ladder is made of variable number of silicon sensors (from 7 to 15) which strips are daisy chained to increase the detection surface while using a limited readout. To connect the n-side strips a Upilex foil with copper strips is used to transmit the signal to the front-end electronics. Since the microstrip detectors are sensitive objects, to avoid contaminations and mechanical defects due to dust particles, the modules are assembled in a clean room. The sensors are aligned with a manual procedure: a precise cut and precise alignment jigs are mandatory. Sensor positions are then measured by metrology (optical measurement). A Upilex foil (long kapton) is then glued on the n-side of the sensors. Afterwards a reinforcement of an ultra-light foam (aerex) is glued on top of the long kapton. The glue curing time is of about 10 hours. Subsequently the n-side front-end electronic board (TFEK hybrid) is glued at the end of the long kapton. A shorter kapton is glued at the end of the silicon array from the p-side to connect the sensor strips to the front-end electronics (TFES hybrid). The first phase of the ladders assembly is concluded by performing the bonding. In the second phase of the assembly the ladder supports (legs) are glued on the reinforcement.....an airex protection is put on the bonds between the hybrid and the kapton on both p and n sides.....then an aluminum box is mounted to protect the front-end electronics. The last step consists in wrapping around the ladder a kapton foil coated with Cu/Au pattern: this electromagnetic shielding plays also the role of a mechanical protection. Finally the ladder is ready for installation on plane!..thermal grease is dispensed between the two hybrids and on the TFEK hybrid cooling region.. h The AMS Tracker Collaboration Presenter: C. Lechanoine Leluc catherine.leluc@physics.unige.ch