Particle fluxes in the inner radiation belt

Using the albedo neutron decay source, the energy spectrum of trapped protons in the inner belt has been calculated from 10 to 700 Mev. This calculation differs from those of Singer and Hess in that a nuclear interaction term, in addition to the energy loss term, has been used in the continuity equation for the steady-state condition. The spectrum agrees well with the published data. This agreement is strong evidence for the albedo neutron decay source. It also indicates that nonadiabatic losses are small for the particles measured here. A second small stack of nuclear emulsions was flown at the lower edge of the inner radiation belt 11 days after the large solar flare of May 10, 1959. The ratio of the proton flux measured on the second flight to that on the first one is 0.8±0.1, indicating that the solar flare had little or no effect on the proton content of the inner belt. A flux of 2±1 tritons/cm2 sec between 126 and 200 Mev was observed; it is attributed to collisions of trapped protons with air nuclei. No other nuclei heavier than protons were seen.