Cosmic Rays in the Earth Magnetosphere: the importance of the External Field models in trajectory reconstruction with AMS-02 data

We developed a backtracing code for Cosmic Rays trajectory reconstruction in the Earth Magnetosphere with last models of Internal (IGRF-11) and External (Tsyganenko 1996 and 2005) field components. Particles can be reconstructed, in case of allowed trajectory, as Primary Cosmic Rays if they reach the outer boundary (magnetopause) or, in case of forbidden trajectory, as Secondary particles if they go back to the inner boundary. During the last solar active period (2011 and 2012) we compared backtracing results on AMS-02 proton and electron data with and without external field model. Using TS05, specifically designed for storm events, we confirmed the well known East-West effect. Moreover we clearly found the day night effect related to the asymmetric shape of the Magnetosphere if considering the External Field, in comparison with the Internal Field only.