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Cosmogenic Radionuclides as an Extension of the Neutron Monitor Era into the Past: Potential and Limitations

Beer, J. ; McCracken, K. ; Abreu, J. ; Heikkilä, U. ; Steinhilber, F.

In: Space Science Reviews, 2013, vol. 176, no. 1-4, p. 89-100

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    Titre
    • Cosmogenic Radionuclides as an Extension of the Neutron Monitor Era into the Past: Potential and Limitations
    Auteur
    • Beer, J.. Eawag, Dübendorf, Switzerland
    • McCracken, K.. Institute of Physical Science and Technology, University of Maryland, College Park, Maryland, USA
    • Abreu, J.. Eawag, Dübendorf, Switzerland
    • Heikkilä, U.. Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW, Australia
    • Steinhilber, F.. Eawag, Dübendorf, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Space Science Reviews, 2013, vol. 176, no. 1-4, p. 89-100. Springer Netherlands
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:316720
    Summary
    The cosmogenic radionuclides, 10Be, 14C and others, provide a record of the paleo-cosmic radiation that extends >10,000 years into the past. They are the only quantitative means at our disposal to study the heliosphere prior to the commencement of routine sunspot observations in the 17th century. The cosmogenic radionuclides are primarily produced by secondary neutrons generated by the galactic cosmic radiation, and can be regarded, in a sense, as providing an extrapolation of the neutron monitor era into the past. However, their characteristics are quite different from the man-made neutron monitor in several important respects: (1)they are sensitive to somewhat lower cosmic ray energies; (2)their temporal resolution is ∼1 to 2 years, being determined by the rapidity with which they are sequestered in ice, biological, or other archives; (3)the statistical precision for annual data is very poor (∼19%); however it is quite adequate (∼5% for 22-year averages) to study the large variations (±40%) that have occurred in the paleo-cosmic ray record in the past between grand solar minima and maxima. The data contains "noise” caused by local meteorological effects, and longer-term climate effects, and the use of principal component analysis to separate these "system” effects from production effects is outlined. The concentrations of 10Be decreased by a factor of two at the commencement of Holocene, the present-day "interglacial”, due to a 100% increase in the ice accumulation rates in polar regions. The use of the 10Be flux to study heliospheric properties during the last glacial is discussed briefly