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Journal Articles

A Review and interpretation of iodine-129 in Earth's surface layers; Towards evaluating the long-term stability of geological environments

Mitsuguchi, Takehiro; Okabe, Nobuaki*; Kokubu, Yoko; Matsuzaki, Hiroyuki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.96 - 110, 2024/12

Geological disposal of high-level radioactive waste requires not only selecting sites appropriate for the waste repository, where its isolation ability would not be damaged by natural phenomena for several tens of thousands of years, but also rationally constructing the disposal system depending on site-specific geological environments and their anticipated long-term variability. Recently, elemental/isotopic compositions of underground fluids (deep groundwaters, hot/cold spring waters, brines associated with oil and natural gas reservoirs, and so on) in Japan have been studied for evaluating the long-term stability of the geological environments of this country. Iodine and its radioactive isotope $$^{129}$$I (half-life = 15.7 million years) are included in the subjects of the study. The current review paper provides overviews of (i) the iodine content and iodine-129/127 ratio ($$^{129}$$I/$$^{127}$$I ratio) of various materials in Earth's surface layers, (ii) relevant sample pretreatments and measurements, and (iii) $$^{129}$$I/$$^{127}$$I data of the underground fluids in Japan, then gives (iv) some interpretations of the fluid $$^{129}$$I/$$^{127}$$I data, along with their problems and uncertainties, and (v) some implications towards evaluating the long-term stability of geological environments.

Journal Articles

Production rates of long-lived radionuclides $$^{10}$$Be and $$^{26}$$Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxes

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

 Times Cited Count:0 Percentile:0.00(Astronomy & Astrophysics)

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 $$^{10}$$Be and $$^{26}$$Al have been accumulating in these rocks, concentrations of $$^{10}$$Be and $$^{26}$$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 $$^{10}$$Be and $$^{26}$$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.

Journal Articles

Identification of hydrogen trapping in aluminum alloys $$via$$ muon spin relaxation method and first-principles calculations

Tsuru, Tomohito; Nishimura, Katsuhiko*; Matsuda, Kenji*; Nunomura, Norio*; Namiki, Takahiro*; Lee, S.*; Higemoto, Wataru; Matsuzaki, Teiichiro*; Yamaguchi, Masatake; Ebihara, Kenichi; et al.

Metallurgical and Materials Transactions A, 54(6), p.2374 - 2383, 2023/06

 Times Cited Count:2 Percentile:33.88(Materials Science, Multidisciplinary)

Although hydrogen embrittlement susceptibility of high-strength Al alloys is recognized as a critical issue in the practical use of Al alloys, identifying the hydrogen trapping or distribution has been challenging. In the present study, an effective approach based on experiment and simulation is proposed to explore the potential trap sites in Al alloys. Zero-field muon spin relaxation experiments were carried out for Al-0.5%Mg, Al-0.2%Cu, Al-0.15%Ti, Al-0.011%Ti, Al-0.28%V, and Al-0.015%V (at.%) in the temperature range from 5 to 300 K. The temperature variations of the dipole field widths have revealed three peaks for Al-0.5%Mg, four peaks for Al-0.2%Cu, three peaks for Al-0.011%Ti and Al-0.015%V. Atomic configurations of the muon trapping sites corresponding to the observed $$Delta$$ peaks are well assigned using the first-principles calculations for the trap energies of hydrogen around a solute and solute-vacancy pair. The extracted linear relationship between the muon $$Delta$$ peak temperature and the trap energy enables us to explore the potential alloying elements and their complex that have strong binding energies with hydrogen in Al alloys.

Journal Articles

$$^{60}$$Fe and $$^{244}$$Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

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:57 Percentile:96.92(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 ($$^{60}$$Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and $$^{244}$$Pu (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of $$^{60}$$Fe to Earth in the last 10 million years and accompanying lower quantities of $$^{244}$$Pu. The $$^{244}$$Pu/$$^{60}$$Fe influx ratios are similar for both events. The $$^{244}$$Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

JAEA Reports

Practical guide on soil sampling, treatment, and carbon isotope analysis for carbon cycle studies

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

JAEA-Technology-2020-012.pdf:3.71MB

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 $$^{14}$$C) and stable carbon ($$^{13}$$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 $$^{13}$$C (and stable nitrogen isotope, $$^{15}$$N) and $$^{14}$$C analyses; and $$^{13}$$C, $$^{15}$$N, and $$^{14}$$C measurements by the use of isotope ratio mass spectrometry and accelerator mass spectrometry (AMS). The guide briefly introduces ways to report $$^{14}$$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.

Journal Articles

Pre- and post-accident $$^{14}$$C activities in tree rings near the Fukushima Dai-ichi Nuclear Power Plant

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:9.83(Geochemistry & Geophysics)

Journal Articles

Grain size dependence of meteoric $$^{10}$$Be concentrations in bed-sediments of Ado and Yasu rivers flowing into Lake Biwa

Fujisawa, Jumpei*; Minami, Masayo*; Kokubu, Yoko; Matsuzaki, Hiroyuki*

JAEA-Conf 2018-002, p.91 - 94, 2019/02

Beryllium-10 ($$^{10}$$Be) of a cosmogenic nuclide precipitates in forms of BeO and Be(OH)$$_{2}$$ attaching with aerosol on the Earth surface. It is accumulated on the sea- and lake-bottoms. Recently, the meteoric $$^{10}$$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 $$^{10}$$Be exists mostly as hydroxide at pH $$>$$5, and is easy to adhere to soil and mineral surface. Therefore, $$^{10}$$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 $$^{10}$$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 $$^{10}$$Be concentration by JAEA-AMS-TONO.

Journal Articles

Age and speciation of iodine in groundwater and mudstones of the Horonobe area, Hokkaido, Japan; Implications for the origin and migration of iodine during basin evolution

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:34 Percentile:77.20(Geochemistry & Geophysics)

Iodine distribution, speciation, and isotope ratio ($$^{129}$$I/$$^{127}$$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.

Journal Articles

Growth of single-phase nanostructured Er$$_2$$O$$_3$$ thin films on Si (100) by ion beam sputter deposition

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:13.17(Materials Science, Coatings & Films)

Single-phase nanocrystalline thin films of Er$$_2$$O$$_3$$ (440) has been first prepared using Si (100) substrates by ion beam sputter deposition at 973 K at a pressure of $$<$$ 10$$^{-5}$$ Pa and $${it in}$$-$${it situ}$$ annealing at 1023 K at a pressure of $$approx$$ 10$$^{-7}$$ Pa. Er silicides formed during the deposition are eliminated via the annealing, which results in the single phase and the smooth surface of the Er$$_2$$O$$_3$$ thin films. The epitaxial relationship between Si (100) and Er$$_2$$O$$_3$$ (110) is clarified by X-ray diffraction and reflection high energy electron diffraction.

Journal Articles

A Study of new preparation method for AMS targets

Katayama, Atsushi; Kameo, Yutaka; Nakashima, Mikio; Matsuzaki, Hiroyuki*

Dai-10-Kai AMS Shimpojiumu Hokokushu, p.234 - 237, 2008/00

The determination of $$^{129}$$I by accelerator mass spectrometry (AMS) has generally been used measurement targets from AgI precipitation. For more sensitive determination of $$^{129}$$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.

Journal Articles

Development of electrochemical hydrogen pump under vacuum condition for a compact tritium gas cycling system

Kato, Mineo; Ito, Takeshi*; Sugai, Hiroyuki; Kawamura, Yoshinori; Hayashi, Takumi; Nishi, Masataka; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

Fusion Science and Technology, 41(3), p.859 - 862, 2002/05

JAERI has a plane to develop a compact tritium gas recycling system for fusion research. This system is also very attractive for the muon-catalyzed fusion ($$mu$$CF) research at RIKEN-RAL Muon Facility in UK. For the research, JAERI has produced high purity tritium gas of 1,500 Ci and transported it to the Facility. In the $$mu$$CF experiments, the tritium gas was diluted by the deuterium in an optional concentration and the used tritium gas was carried back by the tritium transport container developed to JAERI. If it is possible to recycle the diluted tritium gas, i.e., the used tritium gas is enriched in the experimental site, the $$mu$$CF experiments should be conducted efficiently. rom the above point of view, in this paper, we propose the compact tritium gas recycling system based on the gas chromatography that has already developed in JAERI and a proton conductor.

Journal Articles

Measurement of X-rays from muon to $$alpha$$ sticking and fusion neutrons in solid/liquid D-T mixtures of high tritium concentration

Ishida, Katsuhiko*; Nagamine, Kanetada*; Matsuzaki, Teiichiro*; ; ; Sakamoto, Shinichi*; ; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; et al.

Hyperfine Interactions, 118(1-4), p.203 - 208, 1999/00

no abstracts in English

Journal Articles

He accumulation effect in solid and liquid D-T mixture

; Nagamine, Kanetada*; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; ; Sakamoto, Shinichi*; ; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; et al.

Hyperfine Interactions, 118(1-4), p.213 - 215, 1999/00

no abstracts in English

Journal Articles

Muon catalyzed fusion and muon to $$^{3}$$He transfer in solid T$$_{2}$$ studied by X-ray and neutron detection

Matsuzaki, Teiichiro*; Nagamine, Kanetada*; Ishida, Katsuhiko*; ; ; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; Hashimoto, Masashi; Sugai, Hiroyuki; et al.

Hyperfine Interactions, 118(1-4), p.229 - 234, 1999/00

no abstracts in English

Journal Articles

High purity tritium gas supplied by JAERI for muon catalyzed fusion research at RIKEN-RAL muon facilty

Kato, Mineo; Kurosawa, Kiyoyuki; Sugai, Hiroyuki; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

KEK Proceedings 99-11, p.113 - 127, 1999/00

no abstracts in English

Journal Articles

Measurement of the K$$_{beta}$$/K$$_{alpha}$$ ratio of muon to $$alpha$$ sticking X-rays in muon catalyzed d-t fusion at RIKEN-RAL muon facility

; Nagamine, Kanetada*; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; ; Sakamoto, Shinichi*; ; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; et al.

Hyperfine Interactions, 118(1-4), p.209 - 212, 1998/00

no abstracts in English

Journal Articles

Preparation of pure tritium for a liquid D$$_{2}$$/T$$_{2}$$ target of muon-catalyzed fusion experiments

Kudo, Hiroshi; Fujie, Makoto; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; Sugai, Hiroyuki; Umezawa, Hirokazu; Matsuzaki, Teiichiro*; Nagamine, Kanetada*

Applied Radiation and Isotopes, 43(5), p.577 - 583, 1992/00

no abstracts in English

Journal Articles

X-ray observation of $$alpha$$-sticking phenomena in muon catalyzed fusion for a high density D-T mixture with 30% tritium concentration

Nagamine, Kanetada*; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; ; ; ; Miyake, Yasuhiro*; ; ; ; et al.

Muon Catal. Fusion, 5-6, p.289 - 295, 1991/00

no abstracts in English

Oral presentation

None

Mitsuguchi, Takehiro; Okabe, Nobuaki*; Kokubu, Yoko; Matsuzaki, Hiroyuki*

no journal, , 

no abstracts in English

Oral presentation

A Study of new preparation method for AMS targets; Utilizing an adsorption reaction for iodine-129 sample preparation

Katayama, Atsushi; Ishimori, Kenichiro; Kameo, Yutaka; Suzuki, Takashi; Matsuzaki, Hiroyuki*; Kimura, Kenichi*; Kinno, Masaharu*; Amano, Hikaru; Nakashima, Mikio

no journal, , 

no abstracts in English

29 (Records 1-20 displayed on this page)