Radiation Age of a Meteorite from Cosmic-Ray-Produced He 3 and H 3 </mml:mrow…
1957; American Institute of Physics; Volume: 107; Issue: 2 Linguagem: Inglês
10.1103/physrev.107.540
ISSN1536-6065
AutoresF. Begemann, James Geiss, David C. Hess,
Tópico(s)Isotope Analysis in Ecology
ResumoThe tritium and ${\mathrm{He}}^{3}$ contents of the Norton County stone meteorite were measured. At the time of fall (1948) the tritium activity of two different specimens were (0.28\ifmmode\pm\else\textpm\fi{}0.02) and (0.25\ifmmode\pm\else\textpm\fi{}0.02) disintegrations ${\mathrm{min}}^{\ensuremath{-}1}$ ${\mathrm{g}}^{\ensuremath{-}1}$. The measured ${\mathrm{He}}^{3}$ contents per gram were (2.27\ifmmode\pm\else\textpm\fi{}0.11) and (2.35\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ cc STP respectively. Experiments were made which indicate that there has been no appreciable loss of ${\mathrm{He}}^{3}$. The amount of ${\mathrm{He}}^{3}$ accumulated and the tritium production rate combined give apparent ${\mathrm{He}}^{3}$-${\mathrm{He}}^{3}$ ages for irradiation of 420 and 480 million years respectively. If an assumption is made as to the direct production rate of ${\mathrm{He}}^{3}$ by spallation, these ages reduce to 240 and 280 million years. The ${\mathrm{A}}^{40}$-${\mathrm{K}}^{40}$ age of this meteorite is ${4400}_{\ensuremath{-}740}^{+640}$ million years. The possible significance of this difference in age is discussed.
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