Plasma shocks and energetic particles in the outer solar system - Trapping and asymmetry observations from Pioneer 10 and Pioneer 11

The April 15 and 28, 1978 solar flares appear to have 0.5-20 MeV protons trapped between a pair of shocks, and the large count rate enhancement observed, along with large ranges of radial distance and longitudinal angles, imply a prolongation of trapping for a period of weeks. The apparent ability of a shock whose plasma signature is faint to confine MeV protons in the outer solar system may have significant implications for cosmic ray studies. Analytical results also imply significant azimuthal asymmetry in plasma and energetic particle behavior, at distances as far as 16 AU from the sun. Combining these observations provides evidence for unexpectedly complex interactions in the outer solar system between energetic particles and solar wind plasma.