Lunar radionuclide records of average solar-cosmic-ray fluxes over the last ten million years
Because changes in solar activity can modify the fluxes of cosmic-ray particles in the solar system, the nature of the galactic and solar cosmic rays and their interactions with matter are described and used to study the ancient sun. The use of cosmogenic nuclides in meteorites and lunar samples as detectors of past cosmic-ray variations are discussed. Meteorite records of the history of the galactic cosmic rays are reviewed. The fluxes of solar protons over various time periods as determined from lunar radionuclide data are presented and examined. The intensities of solar protons emitted during 1954 to 1964 (11-year solar cycle number 19) were much larger than those for 1965 to 1975 (solar cycle 20). Average solar-proton fluxes determined for the last one to ten million years from lunar /sup 26/Al and /sup 53/Mn data show little variation and are similar to the fluxes for recent solar cycles. Lunar activities of /sup 14/C (and preliminary results for /sup 81/Kr) indicate that the average fluxes of solar protons over the last 10/sup 4/ (and 10/sup 5/) years are several times larger than those for the last 10/sup 6/ to 10/sup 7/ years; however, cross-section measurements and other work are needed to confirm these flux variations.
- Research Organization:
- Los Alamos Scientific Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5517825
- Report Number(s):
- LA-UR-80-928; CONF-7910123-4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AGE ESTIMATION
BARYONS
COSMIC RADIATION
COSMIC RAY FLUX
COSMIC RAY PROPAGATION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
IONIZING RADIATIONS
LUNAR MATERIALS
MATERIALS
NUCLEONS
PHYSICAL RADIATION EFFECTS
PROTONS
RADIATION EFFECTS
RADIATION FLUX
RADIATIONS
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SOLAR SYSTEM
STELLAR RADIATION
VARIATIONS