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Published 1975 | Published
Book Section - Chapter Open

Implications of Time Variations for the Origin of Low Energy Cosmic Ray Nitrogen and Oxygen Nuclei


We report observations of time variations in the quiet time intensity of 5-27 MeV/nuc nitrogen and oxygen and 13-25 MeV/nuc helium nuclei, obtained with the Caltech Electron/Isotope Spectrometers on IMP 7 and 8. We find no significant correlation of the O variations with variations in the low intensity fluxes of 1-2 MeV solar protons. However, we do find the O intensity to be well correlated with the modulation of galactic cosmic rays as measured by neutron monitors. When compared with the neutron monitor, the factor of ~ 3 change in the 0 intensity during 1972 through 1974 is consistent with the factor of ~ 30 increase observed since 1969. These observations imply that the enhanced low energy N and O fluxes are not of solar origin, but originate far enough from the sun that they undergo substantial modulation and have significantly increased access to 1 AU at times of minimum solar modulation. It may be possible to determine the charge state of the He and O by comparing their time variations. The He and O variations are strongly correlated, and both exhibit similar hysteresis effects when compared to the neutron monitor.

Additional Information

© 1975 MPE. Provided by the NASA Astrophysics Data System. This work was supported in part by the National Aeronautics and Space Administration under Contract NAS5-11066 and Grant NGR 05-002-160.

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August 19, 2023
October 26, 2023