Performance of the AMS-02 silicon detector

The Alpha Magnetic Spectrometer (AMS) is a high-energy particle physics experiment in space. Eight layers of double-sided silicon detectors, embedded in a 0.8 T magnetic field created by a superconducting cryo-magnet, are the core of the AMS-02 detector. With a 10 μm spatial resolution, the silicon tracker is able to measure the magnetic rigidity and the sign of the passing particle up to few TV, with a resolution of ΔR/R ∼ 2.5%. In addition the energy loss of the particle in silicon enable the measurement of the absolute charge of nuclei until iron. In this work are presented, in terms of spatial and charge resolution, the performance of the silicon detector in a test beam performed in October 2003 at the CERN SPS.