The Quiet Time Spectra of Low Energy Hydrogen and Helium Nuclei

Abstract

Measurements of the 1972-1973 quiet time hydrogen and helium spectra from 1.3-40 MeV/nuc are discussed. For both spectra the relative-intensity minimum occurs at lower energies than those reported for earlier years. There is no evidence of a low energy turnup in the He spectrum down to 2.4 MeV/nuc. The spectra indicate that the galactic component dominates down to about 10 MeV; a stable, non-solar He-4 component extends from higher energies down to about 2.4 MeV/nuc. At lower energies the periods of minimum H and He intensity do not coincide, and the relative abundance of H and He at 1.3-2.3 MeV/nuc is variable, with H/He ratios ranging from about 3 to about 10. The observations suggest that the 1.3-2.3 MeV/nuc protons and alphas are of solar origin.

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