COSMIC RAY SPECTRUM AT 1 AU: A TRANSMISSION FUNCTION APPROACH TO THE MAGNETOSPHERE

We have used a method based on the transmission function to evaluate the effects of magnetosphere on the galactic cosmic rays at 1AU. The approach is based on calculation of trajectories (back-tracing) of particles in a model of geomagnetic field. Transmission function between AMS-01 orbit, at an altitude of 400 km, and the magnetopause has been built. In this paper we present spectra at 1AU based on AMS-01 data, taken in June 1998. The evaluation of the transmission function for 2005, using CREME96 model, is also presented. This method can be used to recover the spectrum outside the magnetosphere, starting from a measured spectrum of primaries in near Earth orbit, when the conditions of the data taking are known.