Observation and analysis of low-energy solar particle propagation from discrete flare events

The proton, alpha particle, and electron fluxes measured following two west limb solar flare events are analyzed by using numerical solutions to the complete particle transport equation, including considerations of particle convection and energy loss. The values of the obtained mean free paths λr suggest that interplanetary propagation conditions were different during these two events. During the November 4, 1968, event the derived values of λr were ∼0.2–0.3 AU, while during the November 1969 event the derived values of λr were ∼0.1 AU for particles with energies as low as a few MeV. For these events the rise and decay of the alpha and proton flux profiles can be reasonably reproduced with a distant (10 AU) free escape boundary.