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Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Journal Articles

$$omega N$$ scattering length from $$omega$$ photoproduction on the proton near the reaction threshold

Ishikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.

Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05

Journal Articles

Radioactive Cs in the severely contaminated soils near the Fukushima Daiichi Nuclear Power Plant

Kaneko, Makoto*; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota*; Kawamoto, Yuji*; Yamasaki, Shinya*; Nakamatsu, Yuki*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; et al.

Frontiers in Energy Research (Internet), 3, p.37_1 - 37_10, 2015/09

The mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs migration in Fukushima.

JAEA Reports

Thermodynamic data development using the solubility method (Translated document)

Doi, Reisuke; Iwata, Hajime; Kitamura, Akira

JAEA-Review 2014-014, 27 Pages, 2014/05

JAEA-Review-2014-014.pdf:1.77MB

The solubility method is one of the most powerful tools to obtain reliable thermodynamic data for (1) solubility products of discrete solids and double salts, (2) complexation constants for various ligands, (3) development of data in a wide range of pH values, (4) evaluation of data for metals that form very insoluble solids (e.g. tetravalent actinides), (5) determining solubility-controlling solids in different types of wastes and (6) elevated temperatures for redox sensitive systems. This document is focused on describing various aspects of obtaining thermodynamic data using the solubility method. This manuscript deals with various aspects of conducting solubility studies, including selecting the study topic, modeling to define important variables, selecting the range of variables and experimental parameters, anticipating results, general equipment requirements, conducting experiments, and interpreting experimental data.

Journal Articles

Beam-palarization asymmetries for the $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Lambda$$ and $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Sigma$$$$^{0}$$ reactions for $$E$$$$_{gamma}$$=1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat$'e$, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

 Times Cited Count:128 Percentile:94.91(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Evidence for a narrow $$S$$ = +1 Baryon resonance in photoproduction from the neutron

Nakano, Takashi*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Date, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; Fujiwara, Mamoru; et al.

Physical Review Letters, 91(1), p.012002_1 - 012002_4, 2003/07

 Times Cited Count:1003 Percentile:99.86(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Development of "Data-Free-Way" Distributed Database System for Advanced Nuclear Materials

Ueno, Fumiyoshi; Kano, Shigeki; Fujita, Mitsutane*; Kurihara, Yutaka*; Nakajima, Hajime*; Yokoyama, Norio*; Iwata, Shuichi*

Journal of Nuclear Science and Technology, 31(12), p.1314 - 1324, 1994/00

None

Journal Articles

Function and utilization of Data-Free-Way system; Distributed database for advanced nuclear materials

Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; Kano, Shigeki*; Iwata, Shuichi*

Computer Aided Innovation of New Materials,II,Pt. 1, p.81 - 84, 1993/00

no abstracts in English

Journal Articles

On Data-free-way; Distributed material database for nuclear applications

Fujita, Mitsutane*; Nakajima, Hajime; Ueno, Fumiyoshi*; Iwata, Shuichi*

Genshiryoku Kogyo, 39(10), p.53 - 57, 1993/00

no abstracts in English

Journal Articles

Development of a distributed database for advanced nuclear materials: Data-Free-Way System

Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; *; Iwata, Shuichi*

Proc. of the 4th Int. Symp. on Advanced Nuclear Energy Research (JAERI-CONF 1/JAERI-M 92-207), p.402 - 409, 1992/12

no abstracts in English

Journal Articles

System design of pilot data-free-way; Distributed database for advanced nuclear materials

Nakajima, Hajime; ; *; Ueno, Fumiyoshi*; Fujita, Mitsutane*; *; Iwata, Shuichi*

Journal of Nuclear Materials, 191-194, p.1046 - 1050, 1992/00

 Times Cited Count:4 Percentile:41.95(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Present status and future direction of data-free-way; Distributed database for advanced nuclear materials

Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; Kano, Shigeki*; Iwata, Shuichi*

Proc. of the Int. Symp. on Material Chemistry in Nuclear Environment, p.601 - 611, 1992/00

no abstracts in English

Journal Articles

Objective and conceptual design of data-free-way system; Distributed data base for advanced nuclear materials

Fujita, Mitsutane*; Nakajima, Hajime; *; Iwata, Shuichi*

Computer Aided Innovation of New Materials, p.25 - 28, 1991/00

no abstracts in English

Journal Articles

Conceptual design of data-free-way system; Distributed database for advanced nuclear materials

Fujita, Mitsutane*; *; Nakajima, Hajime; *; *; Ueno, Fumiyoshi*; Iwata, Shuichi*

Genshiro Zairyo Dai-122 Iinkai Heisei-2-Nendo Dai-5-Kai Iinkai Shiryo (Nihon Gakujutsu Shinkokai), p.7 - 14, 1991/00

no abstracts in English

Oral presentation

Fate of plutonium derived from the atomic bomb detonated at Nagasaki, Japan

Iwata, Hajime*; Sakamaki, Keiko*; Yasuda, Kenichiro; Onuki, Toshihiko; Utsunomiya, Satoshi*

no journal, , 

The aim of this study is to understand the fate of plutonium derived from atomic bomb, which has been preserved in the bottom sediment for 60 years, based on the investigation of the speciation and size distribution of plutonium. Approximately 60 % of plutonium is present as bound to organic matters and 30 % is present as insoluble species such as Pu oxides. Our results also suggest that the fast transformation of plutonium to the species bound to the organic matter for the period of 60 years, evidencing the important role of the natural organic matters on the plutonium speciation in the environment.

Oral presentation

Alteration of the interface between bentonite and carbon steel under hyper alkaline conditions

Sakamaki, Keiko; Iwata, Hajime*; Utsunomiya, Satoshi*

no journal, , 

no abstracts in English

Oral presentation

Fate of plutonium derived from the atomic bomb detonated at Nagasaki, Japan

Iwata, Hajime*; Kawamoto, Yuji*; Sakamaki, Keiko; Yasuda, Kenichiro; Onuki, Toshihiko; Utsunomiya, Satoshi*

no journal, , 

no abstracts in English

Oral presentation

Solubility of niobium under atmosphere control

Iwata, Hajime; Kitamura, Akira

no journal, , 

The solubility of Nb(V) under atmosphere control by using oversaturation and undersaturation method. In the obtained results, Significant difference is observed in the solubility of Nb, and at high pH, the effect of colloid was not observed. These results were compared with the existing thermodynamic data.

Oral presentation

Solubility of Niobium in aqueous solution containing high pH conditions

Iwata, Hajime; Kitamura, Akira

no journal, , 

The solubility of Nb was measured using oversaturation and undersaturation method. Compared with the values evaluated using JAEA-TDB, in the OS method a similar solubility was observed, and the measured values in the US method were around three orders magnitude below the evaluated values. It suggests that the solubility limiting solid differ between OS and US method.

Oral presentation

pH and ionic strength dependency of Nb solubility

Iwata, Hajime; Kitamura, Akira

no journal, , 

The solubility of Nb was measured using oversaturation and undersaturation method. Compared with the values evaluated using JAEA-TDB, in the OS method a similar solubility was observed, and the measured values in the US method were around three orders magnitude below the evaluated values. It suggests that the solubility limiting solid differ between OS and US method.

29 (Records 1-20 displayed on this page)