Apollo 17 cosmic-ray experiment: interplanetary heavy nuclei of energies 0.05 to 5.0 MeV per atomic mass unit.
Abstract
Glass detectors were exposed to interplanetary heavy ions for 45.5 hr on the moon during Dec. 12 and 13, 1972. In the energy range 0.05-5.0 MeV per amu, the differential flux of iron-group nuclei was found to be a power-law spectrum of the form 1/E cubed. During the experiment, solar activity was low, as inferred from both ground-based observations of solar activity and satellite measurements of particles in interplanetary space. The Fe/alpha-ratio at about 1 MeV per amu was enhanced by a factor of about 10 above the solar ratio. A pair of detectors that were exposed in both the solar and antisolar directions gave identical spectral shapes, with the flux from the solar direction being twice that from the antisolar direction. Collectively, the observations of solar-related anisotropy and the 1/E cubed spectra, and the factor of about 10 enhancement in the Fe/alpha-ratio, imply strongly that these heavy ions are solar in origin.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1975
- DOI:
- 10.1086/153591
- Bibcode:
- 1975ApJ...198..183W
- Keywords:
-
- Apollo 17 Flight;
- Cosmic Rays;
- Heavy Nuclei;
- Interplanetary Space;
- Solar Activity Effects;
- Corpuscular Radiation;
- Heavy Ions;
- Power Spectra;
- Spaceborne Astronomy;
- Space Radiation