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Yasue, Kenichi; Hirouchi, Daisuke*; Matsubara, Akihiro; Kokubu, Yoko
no journal, ,
no abstracts in English
Watanabe, Takahiro; Kokubu, Yoko; Fujita, Natsuko; Matsubara, Akihiro*; Nishio, Tomohiro*; Miyake, Masayasu; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; Nishizawa, Akimitsu*; et al.
no journal, ,
Radiocarbon dating by Accelerator Mass Spectrometry is widely used for earth and environmental sciences. For high-precision analyses, automatic preparation system and standard methods are needed. The preparation system by elemental analyzer (EA) has been reported. However, we should make clear the changes in background level during the preparation. In this study, we continued radiocarbon dating of international standard materials using the EA at JAEA-AMS-TONO. The radiocarbon concentrations of the standard materials were agreement with the consensus values within 
2 sigma.
Wakatsuki, Tsuyoshi*; Yamada, Ryuji*; Kokubu, Yoko
no journal, ,
Many soil slips and debris flows on the welded-tuff slopes were induced by heavy rain on July 28, 2013 in Tsuwano, Shimane. The debris flows eroded sidewalls or streambeds in river channels and the sediments driven by earlier slope movements were exposed in places. In six outcrops, we collected 53 dead wood chip samples presumably buried at the sediment deposition, and radiocarbon dating was performed. At around 418 m asl in Nayoshi district, Tsuwano, the outcrops of the black-clayey sediments are found, which are supposed to have deposited in a past dammed lake. They are distributed at upstream of a topographically-estimated deposit zone for an ancient large-scale slope failure, and the calendar-calibrated ages of these sediments ranges from 41 to 55 ka BP. It is therefore conjectured that the slope failure had occurred before 55 ka BP and the dammed lake had burst after 41 ka BP. An average deposition rate of about 0.3 m/1000 y was estimated at an outcrop of the dammed lake sediments
Hakozaki, Masataka*; Sakamoto, Minoru*; Kokubu, Yoko; Fujita, Natsuko; Li, Z.*; Nakatsuka, Takeshi*
no journal, ,
The sacred tree, a large cedar tree, at the Zinmei Shrine in Mizunami City, Gifu Prefecture was collapsed by heavy rain. Using a part of the tree, we have started measuring its radiocarbon in order to obtain the basic data of calibration curve required for radiocarbon dating. In this presentation, we report the result of age determination of the tree.