Present Status of YU-AMS System

Tokanai, Fuyuki; Kato, Kazuhiro; Anshita, Minoru; Sakuraï, H.; Izumi, Akihiro; Toyoguchi, Teiko; Kobayashi, Takeshi; Miyahara, Hiroko; Ohyama, Motonari; Hoshino, Yujiro

doi:10.1017/s0033822200057350

Cited by 19 publications

(15 citation statements)

References 16 publications

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“…Fine The sample preparation processing, including an oxidation (cellulose → CO 2 ), a CO 2 purification (process of removing impurities using cold traps), the graphitization (CO 2 → C: hydrogen reduction with Fe catalyst), and the AMS measurement were conducted at Yamagata University. The AMS system in Yamagata University (YU-AMS) is based on a conventional AMS instrument (Tokanai et al 2013). The 14 C content in six new NIST standards and two blank samples were also measured with the unknown samples.…”

Section: Methodsmentioning

confidence: 99%

Verification of the Cosmic-Ray Event in AD 993–994 by Using a Japanese Hinoki Tree

et al. 2014

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A rapid yearly increase in the radiocarbon content has been detected for the period from AD 993 to 994. However, this event is supported by the 14 C measurements of only one cedar tree sample, and verification is necessary to confirm this event more reliably. For this purpose, this study measured the 14 C content in Japanese Hinoki tree rings corresponding to the period from AD 988 to 997 using the accelerator mass spectrometry system at Yamagata University (YU-AMS). The result shows a significant 14 C increase from AD 993 to 994, and is consistent with the previously measured data for the Japanese cedar tree. This marks the second case detecting an increased 14 C level corresponding to the AD 994 event.

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Section: Methodsmentioning

confidence: 99%

Verification of the Cosmic-Ray Event in AD 993–994 by Using a Japanese Hinoki Tree

et al. 2014

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“…The weight ratios of the graphite to 1 mg of iron powder were kept between 0.6 and 1.2. Measurements of 14 C in the graphite samples were carried out using a 500 KV tandem accelerator at the Yamagata University (YU-AMS) 29 . The 14 C concentrations for the graphite samples were obtained using the measured values of the 14 C/ 12 C ratio for samples and 4990 C oxalic acid, which is a standard sample.…”

Section: Pretreatments and Measurementsmentioning

confidence: 99%

Prolonged production of 14C during the ~660 BCE solar proton event from Japanese tree rings

Sakuraï

Tokanai

Miyake

et al. 2020

Sci Rep

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Annual rings record the intensity of cosmic rays (CRs) that had entered into the Earth's atmosphere. Several rapid 14 C increases in the past, such as the 775 CE and 994CE 14 C spikes, have been reported to originate from extreme solar proton events (SPEs). Another rapid 14 C increase, also known as the ca. 660 BCE event in German oak tree rings as well as increases of 10 Be and 36 Cl in ice cores, was presumed similar to the 775 CE event; however, as the 14 C increase of approximately 10‰ in 660 BCE had taken a rather longer rise time of 3-4 years as compared to that of the 775 CE event, the occurrence could not be simply associated to an extreme SPE. In this study, to elucidate the rapid increase in 14 C concentrations in tree rings around 660 BCE, we have precisely measured the 14 C concentrations of earlywoods and latewoods inside the annual rings of Japanese cedar for the period 669-633 BCE. Based on the feature of 14 C production rate calculated from the fine measured profile of the 14 C concentrations, we found that the 14 C rapid increase occurred within 665-663.5 BCE, and that duration of 14 C production describing the event is distributed from one month to 41 months. The possibility of occurrence of consecutive SPEs over up to three years is offered.www.nature.com/scientificreports www.nature.com/scientificreports/ respectively, calculated at every latitude taking account of a geomagnetic cut off rigidity 35 from their fluence spectra and the altitude production yields. The production rate of SPE56 was consistent with the value 2.90 × 10 6 [atoms/cm 2 ] by Kovaltsov et al. 23 . Based on our calculation, the ~660 BCE event is 52-53 times larger than SPE56, and 230-240 times larger than SPE72 if the energy spectrum of the ~660 BCE event is comparable to the SPEs.

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“…This new multipurpose tandem accelerator will see various uses, including, AMS, IBA, ion irradiation, and nuclear physics. The new system will start routine multi-nuclide AMS measurements of 10 Be, 14 Fig. 3.…”

Section: Discussionmentioning

confidence: 99%

“…14 C-AMS using a CO 2 gas-ion source is intended to improve lowbackground and high-repeatability measurements. We also installed an automatic sample-preparation system [14] with an elemental analyzer and a gas chromatograph for 14 C samples.…”

Section: Ams Performancementioning

confidence: 99%

“…The rare-particle detection system on the tandem accelerator (Tsukuba 6 MV AMS system) is designed for the high-sensitivity http://dx.doi.org/10.1016/j.nimb.2015.04.028 0168-583X/Ó 2015 Elsevier B.V. All rights reserved. detection of 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, and 129 I, and is expected also to measure other radioisotopes such as 32 Si and 90 Sr.…”

Section: Introductionmentioning

confidence: 99%

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