Cosmic Rays at the Edge of the Solar System

I report on the properties of galactic cosmic-ray modulation in the interface separating the solar system material from the surrounding interstellar cloud. Specifically, I consider (a) the response of cosmic rays to the tilt of the heliospheric current sheet in the inner heliosheath via the Hill-Florinski effect, and (b) the effect of turbulent activity driven by MHD instabilities at the heliopause on cosmic-ray diffusion in the outer heliosheath. The work is performed using a four-dimensional computer model of energetic charged particle transport based on the stochastic phase space trajectory integration method and the plasma model-derived global structure of the heliosphere. A novel application of the trajectory method is used to deduce the interstellar galactic cosmic-ray intensity from the intensities in the heliosheath measured by the Voyager space probes.