Geomagnetically trapped alpha particles: 1. Off-equator particles in the outer zone

The population of trapped alpha particles in five contiguous energy channels between 0.85 and 9.0 Mev was measured in the B and L intervals 2 ≤ L ≤ 4 and 0.06 ≤ B ≤ 0.35 gauss during June and July 1969. The particle distribution functions of these particles suggest that the location of the source of these particles is at L > 4 and that inward radial diffusion determines the spatial and energy distributions. The particle distribution functions show that these alpha particles do not diffuse into the inner zone. These results provide no support for the concepts of in-situ acceleration or direct capture of energetic solar alpha particles.