2016 Fiscal Year Final Research Report
Dating of presolar grains by nuclear cosmochronology
| Project/Area Number |
15K13602
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Geochemistry/Cosmochemistry
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
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| Project Period (FY) |
2015-04-01 – 2017-03-31
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| Keywords | U-Th核年代法 / プレソーラー粒子 / TIMS / r-process |
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| Outline of Final Research Achievements |
High precision analysis of U and Th abundances is key for dating presolar grains by U-Th nuclear cosmochronology. In this study, we have developed an isotope dilution TIMS method that enables the determination of 1 pg U and Th with analytical reproducibilities of 0.45% and 1.3%, respectively. The U-Th cosmochronology with this method would provide a 0.7 Gyr of uncertainty for the age of presolar grains determined.
On the other hand, we constrained the origin and evolution of r-process nuclides in the solar vicinity by a new theoretical study that combined the chemical composition of meteorites with galactic chemical evolution models and astronomical observations. Consequently, the timing of last r-process nucleosynthesis that contributed the solar system was determined to be 0.13-0.14 Gyr before the onset of solar system formation.
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| Free Research Field |
宇宙化学
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