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Lunar radionuclide records of average solar-cosmic-ray fluxes over the last ten million yearsThe use of cosmogenic radionuclides in lunar materials as indicators of solar cosmic ray fluxes and thus solar activity over the past 10 million years is discussed. The nature of solar and galactic cosmic ray particles and their interactions with matter are reviewed, with particular emphasis on nuclide production by cosmic-ray-induced nuclear reactions. Evidence of galactic cosmic ray flux variations from measurements of radionuclide activities in meteorites is considered which has indicated changes of less than about 25-50% over the last few million years. Measurements of radionuclide activities in lunar materials which are used to determine solar cosmic ray fluxes are then examined together with direct proton measurements indicating variations in solar fluxes with different solar cycles. It is noted that whereas average solar proton fluxes determined for the last 1-10 million years from Al-26 and Mn-53 data show little variation and are similar to recent values, lunar C-14 and Kr-81 activities indicate average solar proton fluxes several times greater over the past 10,000 to 100,000 years.
Document ID
19810064423
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Reedy, R. C.
(California, University Los Alamos Scientific Laboratory, Los Alamos, NM, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1980
Subject Category
Lunar And Planetary Exploration
Report/Patent Number
LA-UR-80-928
CONF-7910123-4
Meeting Information
Meeting: Conference on The ancient sun: Fossil record in the earth, moon and meteorites
Location: Boulder, CO
Start Date: October 16, 1979
End Date: October 19, 1979
Accession Number
81A48827
Funding Number(s)
CONTRACT_GRANT: NASA ORDER W-14084
Distribution Limits
Public
Copyright
Other

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