Evidence for Primary Interstellar Cosmic-Ray Electrons

We have performed a comparative study of the absolute solar modulation of cosmic-ray positrons (e^+) and electrons (e^+ + e^-). We find that the interstellar electron spectrum, which is described by a power-law slope at higher energies, must flatten below ~ 100 MeV, that a significant fraction of interstellar cosmic-ray electrons must originate in "primary" sources, and that the rigidity dependence of the interplanetary cosmic-ray diffusion coefficient, R^α, changes from α>O at higher rigidities to α ≈ -1 below ~ 60 MV.