Atmospheric Secondary Particles In Near Earth Space

In June 1998, the Alpha magnetic spectrometer AMS [1] had a test flight on board space shuttle and recorded some 108 events. The AMS proton and leptons spectrum [2, 3] have a magnetic latitude dependence. The spectral shape of primary cosmic rays can be explained by the geomagnetic rigidity cutoff. However, below the rigidity cutoff, a second spectrum was clearly seen. The energy of this second spectrum is as high as 6 GeV, 10 times higher than previous measured energy in the radiation belts! Beside this apparent difference, these second spectrum particles have similar trajectories as particles in trapped radiation, however, the fate are quite different. The discovery of these GeV sub-rigidity particles create new questions about the radiation belts and the atmospheric neutrinos flux. In this article, the trajectories of these particles are simulated in the same condition as AMS. They are shown to explain the complex behaviors of these secondary particles.