Atmospheric Neutrons and Their Contributions to the Earth's Radiation Belts.

The nature of atmospheric neutrons as well as their contributions to the earth's radiation belts are discussed. Our estimates of the trapped proton fluxes from atmospheric neutrons indicate that GRAND, cosmic ray albedo neutron decay, is the major source of protons (E>30MeV) in the radiation belts for L≤1.8. More trapped proton differential energy measurements at L>1.8 are required in order to test the CRAND theory at L>1.8.The CRAND as well as the solar proton albedo neutron decay (SPAND) source is found too weak to supply the large low energy (≤10MeV) inner zone proton intensities.However, the inner zone proton fluxes from our cross-L diffusion calculations are in reasonable agreement with the observed fluxes at energies ≤30MeV. Diffusion inward from the solar wind appears to be the major source of the low energy inner zone protons.