| Project/Area Number |
17540230
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Yamagata University |
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Principal Investigator |
SAKURAI Hirohisa Yamagata University, Department of Physics, Professor, 理学部, 教授 (60150265)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUZAKI Hiroyuki Tokyo University, Department of Nuclear Science and Technology, Associate Professor, 工学系研究科, 助教授 (60313194)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | cosmic rays / radiocarbon / single-yr tree rings / 25000 years ago / heliosphere / solar activity / 11-year / 22年変動 / 年代測定 / 地磁気変動 |
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| Research Abstract |
We have measured the ^<14>C concentrations in single-year tree rings of an old wood sample before approximately 25000years, using accelerated mass spectrometry (AMS). The ^<14>C concentrations of consecutive 26 single-year tree rings were measured producing the 60 graphite samples for the AMS. The counting accuracy was approximately 0.7% because of the measurement of two graphite samples for each tree ring. The radiocarbon age was 22271±118 yrBP on average for the 26 tree rings, indicating the calendar age of 26778±178 yrBP by the age calibration program of Faibanks0107. Time profile of the radiocarbon ages for 26 single-yr tree rings implied a variability with two humps indicating an interval of approximately 12-year. The heights of sharp and dull humps were 157 yrBP and 109 yrBP from the moving average curve, respectively. They are corresponding to the ^<14>C concentrations of 2.0% and 1.4%, respectively. As the ^<14>C concentrations of this era before 25000 years was 40% higher than that at present time, the variation is suggestive solar periodic activities such as 11-year and/or 22-year.
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