The AMS-02 Time of Flight System

The Time-of-Flight (TOF) system of the AMS detector gives the fast trigger to the read out electronics and measures velocity, direction and charge of the crossing particles. The first version of the detector (called AMS-01) has own in 1998 aboard of the shuttle Discovery for a 10 days test mission, and collected about 10^8 events. The new version (called AMS- 02) will be installed on the International Space Station and will operate for at least three years, collecting roughly 10^{10} Cosmic Ray (CR) particles. The TOF system of AMS-01 successfully operated during the test mission, obtaining a time resolution of 120 ps for protons and better for other CR ions. The TOF system of AMS-02 will be different due to the strong fringing magnetic field and weight constraints.