The Alpha Magnetic Spectrometer on the International Space Station

The Alpha Magnetic Spectrometer (AMS) is a particle physics detector designed to measure charged cosmic ray spectra up to the TV region, with high-energy photon detection capability up to few hundred GeV, AMS is a superconducting spectrometer with large acceptance, long duration (at least three years for the magnet) and state of the art particle identification techniques. AMS will investigate the composition of cosmic rays with high statistics and provide the most sensitive search for the existence of antimatter nuclei and for the nature of dark matter. The detector is being constructed with an eight-layer Silicon Tracker inside a large superconducting magnet, providing a similar to 0.8 Tm-2 bending power and an acceptance of similar to 0.4 m(2) sr. A Transition Radiation Detector and a three-dimensional Electromagnetic Calorimeter allow for electron, positron and photon identification, while a Time of Flight scintillating system and a Ring Image Cerenkov detector perform independent velocity measurements. This complex apparatus will identify and measure nuclei up to Iron. We will describe the overall detector construction and performance, which is due to be com pleted by 2006. The detector will be installed on ISS (International Space Station) in 2008.