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Sakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.
Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05
Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as Be and Al have been accumulating in these rocks, concentrations of Be and Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced Be and Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.
Wallner, A.*; Froehlich, M. B.*; Hotchkis, M. A. C.*; Kinoshita, N.*; Paul, M.*; Martschini, M.*; Pavetich, S.*; Tims, S. G.*; Kivel, N.*; Schumann, D.*; et al.
Science, 372(6543), p.742 - 745, 2021/05
Times Cited Count:41 Percentile:96.64(Multidisciplinary Sciences)Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust-iron-60 (Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and Pu (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of Fe to Earth in the last 10 million years and accompanying lower quantities of Pu. The Pu/Fe influx ratios are similar for both events. The Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.
Koarashi, Jun; Atarashi-Andoh, Mariko; Nagano, Hirohiko*; Sugiharto, U.*; Saengkorakot, C.*; Suzuki, Takashi; Kokubu, Yoko; Fujita, Natsuko; Kinoshita, Naoki; Nagai, Haruyasu; et al.
JAEA-Technology 2020-012, 53 Pages, 2020/10
There is growing concern that recent rapid changes in climate and environment could have a significant influence on carbon cycling in terrestrial ecosystems (especially forest ecosystems) and could consequently lead to a positive feedback for global warming. The magnitude and timing of this feedback remain highly uncertain largely due to a lack of quantitative understanding of the dynamics of organic carbon stored in soils and its responses to changes in climate and environment. The tracing of radiocarbon (natural and bomb-derived C) and stable carbon (C) isotopes through terrestrial ecosystems can be a powerful tool for studying soil organic carbon (SOC) dynamics. The primary aim of this guide is to promote the use of isotope-based approaches to improve our understanding of the carbon cycling in soils, particularly in the Asian region. The guide covers practical methods of soil sampling; treatment and fractionation of soil samples; preparation of soil samples for C (and stable nitrogen isotope, N) and C analyses; and C, N, and C measurements by the use of isotope ratio mass spectrometry and accelerator mass spectrometry (AMS). The guide briefly introduces ways to report C data, which are frequently used for soil carbon cycling studies. The guide also reports results of a case study conducted in a Japanese forest ecosystem, as a practical application of the use of isotope-based approaches. This guide is mainly intended for researchers who are interested but are not experienced in this research field. The guide will hopefully encourage readers to participate in soil carbon cycling studies, including field works, laboratory experiments, isotope analyses, and discussions with great interest.
Matsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsumura, Masumi*; Satou, Yukihiko; Shen, H.*; Sueki, Keisuke*; Matsuzaki, Hiroyuki*
Radiocarbon, 61(6), p.1633 - 1642, 2019/12
Times Cited Count:2 Percentile:11.51(Geochemistry & Geophysics)Fujisawa, Jumpei*; Minami, Masayo*; Kokubu, Yoko; Matsuzaki, Hiroyuki*
JAEA-Conf 2018-002, p.91 - 94, 2019/02
Beryllium-10 (Be) of a cosmogenic nuclide precipitates in forms of BeO and Be(OH) attaching with aerosol on the Earth surface. It is accumulated on the sea- and lake-bottoms. Recently, the meteoric Be is attracting attention as a powerful tool for investigating the past climate change, because it is affected by the earth- and lorcal- cyclical changes of materials such as atmosphere and water circulation. The Be exists mostly as hydroxide at pH 5, and is easy to adhere to soil and mineral surface. Therefore, Be concentration in sediment could be influenced by its grain size composition because fine-grained sediment has a big surface area per unit mass. The purpose of this study is to reveal the relationship between Be concentrations and the grain-size of river sediments. The samples used were bottom-sediments of 18 rivers flowing into Lake Biwa, Japan. The sediments were sieved to 5 fractions and analyzed each for Be concentration by JAEA-AMS-TONO.
Togo, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Suzuki, Yohei*; Terada, Yasuko*; Muramatsu, Yasuyuki*; Ito, Kazumasa*; Iwatsuki, Teruki
Geochimica et Cosmochimica Acta, 191, p.165 - 186, 2016/10
Times Cited Count:28 Percentile:73.97(Geochemistry & Geophysics)Iodine distribution, speciation, and isotope ratio (I/I) in both rock and groundwater phases were determined to investigate long-term migration of iodine in diatomaceous and siliceous shale. It was suggested that I is released to the ground water during the progress of the maturation of organic matter. Dissociated I could move toward the surface because of the upward water flow driven by the compaction during burial diagenetic process. Thus, iodine rich brine is created by integration of iodine released from underlying formations. Because of low affinity of I to solid phase, released I remains in solution phase, and the concentration of the iodine in the solution has been possibly increasing during sedimentation history.
Mao, W.*; Fujita, Masaya*; Chikada, Takumi*; Yamaguchi, Kenji; Suzuki, Akihiro*; Terai, Takayuki*; Matsuzaki, Hiroyuki*
Surface & Coatings Technology, 283, p.241 - 246, 2015/12
Times Cited Count:3 Percentile:13.81(Materials Science, Coatings & Films)Single-phase nanocrystalline thin films of ErO (440) has been first prepared using Si (100) substrates by ion beam sputter deposition at 973 K at a pressure of 10 Pa and - annealing at 1023 K at a pressure of 10 Pa. Er silicides formed during the deposition are eliminated via the annealing, which results in the single phase and the smooth surface of the ErO thin films. The epitaxial relationship between Si (100) and ErO (110) is clarified by X-ray diffraction and reflection high energy electron diffraction.
Katayama, Atsushi; Kameo, Yutaka; Nakashima, Mikio; Matsuzaki, Hiroyuki*
Dai-10-Kai AMS Shimpojiumu Hokokushu, p.234 - 237, 2008/00
The determination of I by accelerator mass spectrometry (AMS) has generally been used measurement targets from AgI precipitation. For more sensitive determination of I, it is necessary to reduce the quantity of iodine carrier for precipitation. But, more than 1mg is the amount of carrier stable iodine needed at present to make a reliable sample treatment and AMS determination. In this study, we examined the basics of procedures of the direct measurement target that used adsorption reaction of the molecular iodine to the metal silver surface in substitution for precipitation. Using this procedure, we have prepared measurement targets with a carrier from 1 to 0.2 mg iodine.
Nemoto, N.*; Shindo, Hiroyuki*; *; Kuboyama, Satoshi*; Oshima, Takeshi; Ito, Hisayoshi; Nashiyama, Isamu; Matsuda, Sumio*
Proceedings of 3rd International Workshop on Radiation Effects on Semiconductor Devices for Space Application, p.154 - 159, 1998/00
no abstracts in English
Katayama, Atsushi; Ishimori, Kenichiro; Kameo, Yutaka; Suzuki, Takashi; Matsuzaki, Hiroyuki*; Kimura, Kenichi*; Kinno, Masaharu*; Amano, Hikaru; Nakashima, Mikio
no journal, ,
no abstracts in English
Katayama, Atsushi; Ishimori, Kenichiro; Kameo, Yutaka; Suzuki, Takashi; Kinno, Masaharu*; Kimura, Kenichi*; Matsuzaki, Hiroyuki*; Nakashima, Mikio
no journal, ,
no abstracts in English
Shimamoto, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Muramatsu, Yasuyuki*; Iwatsuki, Teruki
no journal, ,
Study of migration of iodine in the subsurface environment is important for natural analogue of HLW. The vertical distribution of iodine concentration, the type of iodine, and isotope were analyzed for the sample of groundwater and sedimentary rocks of the Horonobe area. The results showed that iodine ion were existed in the groundwater, and the mixed iodine with organic and inorganic type were existed in the rock samples.
Shimamoto, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Muramatsu, Yasuyuki*; Iwatsuki, Teruki
no journal, ,
We determined iodine distribution, speciation, and isotope ratio (I/I), to investigate long-term migration of iodine in diatomaceous and siliceous shales, using core and groundwater samples collected at JAEA Horonobe underground research center. Iodine in core samples dramatically decreased near the boundary between Wk and Kt Formations. Iodine exists as I in groundwater, while that in shales is a mixture of organic and inorganic I. Iodine isotope ratio (I/I) is slightly higher in siliceous shale compared with that of groundwater. According to these results, migration of iodine in this area can be expected as follows; (1) iodine accumulated as organic iodine in siliceous sediment. (2) Iodine was released from Wk Formation during diagenetic process as I to form iodine-rich groundwater. (3) Iodine-rich groundwater was distributed to Wk and Kt Formations due to the compaction of the layers. (4) Both iodine and chlorine were diluted by freshwater from the surface.
Togo, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Muramatsu, Yasuyuki*; Iwatsuki, Teruki
no journal, ,
To understand behavior of iodine in shallow and deep underground is essential because radioactive wastes, which contain high levels of radioiodine, are planned to be stored in underground nuclear-waste repository. We determined iodine distribution, speciation, and isotope ratio (I/I), to investigate long-term migration of iodine in diatomaceous and siliceous shales, using core and groundwater samples collected at JAEA Horonobe underground research center. Iodine exists as I- in groundwater, while that in shales is a mixture of organic and inorganic I.
Kokubu, Yoko; Matsubara, Akihiro; Nishizawa, Akimitsu*; Owaki, Yoshio*; Nishio, Tomohiro*; Ishimaru, Tsuneari; Matsuzaki, Hiroyuki*
no journal, ,
no abstracts in English
Togo, Yoko*; Takahashi, Yoshio*; Amano, Yuki; Matsuzaki, Hiroyuki*; Suzuki, Yohei*; Muramatsu, Yasuyuki*; Iwatsuki, Teruki
no journal, ,
Radioactive iodine (I) is one of the available indexes of long-term migration of groundwater solutes, because of its long half-life (15.7 million years) and low sorption characteristics. All rock and groundwater samples were collected at Horonobe underground research center. Species of iodine in groundwater was mainly I. I/I isotope ratios in groundwater were lower than that in rocks and almost constant at various depths, demonstrating that iodine in groundwater was released from deeper than co-existing rocks.
Tomita, Ryohei*; Matsunaka, Tetsuya*; Honda, Maki*; Satou, Yukihiko; Matsumura, Masumi*; Takahashi, Tsutomu*; Sakaguchi, Aya*; Matsuzaki, Hiroyuki*; Sasa, Kimikazu*; Sueki, Keisuke*
no journal, ,
no abstracts in English