The Elemental Composition of 4-30 MeV/nuc Cosmic Ray Nuclei with 1 ≤ Z ≤ 8
Recent observations of low energy cosmic rays have shown enhanced fluxes of nitrogen and oxygen relative to other elements in the ~8-30 MeV/nuc energy interval. We have extended the measurements of lithium through oxygen down to ~ 4 MeV/nuc with the Caltech Electron/Isotope Spectrometers on IMP-7 and -8 during solar quiet periods from October 1972 to September 1974. We find no evidence for significant enhancements of Li, Be, B. or C, which are found to have energy spectra consistent with those expected from the adiabatic deceleration of higher energy galactic cosmic rays. The He, N, and O fluxes are greatly enhanced when compared to the other elements, with relative abundances of O/He ~ 0.25, O/B ~ 100, and O/C ~ 30 at ~ 5 to 12.5 MeV/nuc.
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.
Published - 1975-10.pdf