Heidelberg 2015 – wissenschaftliches Programm
UP 7.5: Vortrag
Donnerstag, 26. März 2015, 12:45–13:00, C/gHS
Studying the constancy of galactic cosmic rays using cosmogenic noble gases and radionuclides in iron meteorites — •Thomas Smith1, Ingo Leya1, Silke Merchel2, Georg Rugel2, Stefan Pavetich2, Anton Wallner3, Keith Fifield3, Stephen Tims3, and Gunter Korschinek4 — 1University of Bern, Switzerland — 2Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 3The Australian National University, Canberra, Australia. — 4TU Munich, Germany.
Cosmogenic noble gases and radionuclides in meteorites are the only tools that provide information about the cosmic ray exposure (CRE) history of meteorites. In space, meteoroids are irradiated by galactic cosmic ray (GCR), which produces, among others, stable and radioactive cosmogenic nuclides. It has been demonstrated that periodic variations in the GCR intensity induce periodic peaks in the CRE age histograms. Therefore, searching for periodic peaks in CRE histograms enables one to obtain information about GCR fluency variations. Since expected GCR fluency variations have periodicities of a few hundred million years, one needs meteorites irradiated for at least that long. Iron meteorites, which have CRE ages ranging from a few million to a few billion years, are the best candidates. So far we measured noble gases and radionuclides in 28 iron meteorites by noble gas mass spectrometry and accelerator mass spectrometry. First CRE age histograms have been established and will be presented. Further analyses are ongoing and will improve the statistical interpretation, providing new information on the temporal variability of the GCR fluency.