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Journal Articles

Incommensurate helimagnetic structure of Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ determined by single-crystal neutron diffraction

Tanaka, Seiya*; Kiyanagi, Ryoji; Ishikawa, Yoshihisa*; Amako, Yasushi*; Iiyama, Taku*; Futamura, Ryusuke*; Maruyama, Kenichi*; Utsumi, Shigenori*

Physical Review Materials (Internet), 7(1), p.014403_1 - 014403_11, 2023/01

https://doi.org/10.1103/PhysRevMaterials.7.014403

Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)

Journal Articles

Magnetic phase diagram of helimagnetic Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ (0 x 0.2) hexagonal ferrite

Maruyama, Kenichi*; Tanaka, Seiya*; Kiyanagi, Ryoji; Nakao, Akiko*; Moriyama, Kentaro*; Ishikawa, Yoshihisa*; Amako, Yasushi*; Iiyama, Taku*; Futamura, Ryusuke*; Utsumi, Shigenori*; et al.

Journal of Alloys and Compounds, 892, p.162125_1 - 162125_8, 2022/02

https://doi.org/10.1016/j.jallcom.2021.162125

Times Cited Count：2 Percentile：15.51(Chemistry, Physical)

Journal Articles

Flux growth and magnetic properties of helimagnetic hexagonal ferrite Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ single crystals

Utsumi, Shigenori*; Tanaka, Seiya*; Maruyama, Kenichi*; Amako, Yasushi*; Kiyanagi, Ryoji; Nakao, Akiko*; Moriyama, Kentaro*; Ishikawa, Yoshihisa*; 9 of others*

ACS Omega (Internet), 5(38), p.24890 - 24897, 2020/09

https://doi.org/10.1021/acsomega.0c03671

Times Cited Count：4 Percentile：20.20(Chemistry, Multidisciplinary)

Fabricating large, high-crystalline-quality single-crystal samples of hexagonal ferrite Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ is the first important step to elucidating its helimagnetic structure and developing it for further applications. In this study, single crystals of Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ of various Sc concentrations were successfully grown by the spontaneous crystallization method using Na $_{2}$ O-Fe $_{2}$ O $_{3}$ flux. X-ray diffraction and elemental analysis revealed that the obtained crystals were composed of single-phase Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ of high crystalline quality. The temperature dependence of magnetization and the magnetization curves at 77 K of the = 0.128 crystal exhibited behavior characteristics of helimagnetism. Neutron diffraction measurements of the = 0.128 crystal exhibited magnetic satellite reflection peaks below 211K, proving evidence that Ba(Fe $_{1-x}$ Sc $_{x}$ ) $_{12}$ O $_{19}$ behaves as a helimagnetic material.

Journal Articles

The Present situation and future prospects of groundwater colloids studies on the performance assessment of geological disposal of radioactive wastes in Japan

Nagao, Seiya*; Niibori, Yuichi*; Tanaka, Tadao; Sasaki, Takayuki*; Saito, Takumi*; Kirishima, Akira*; Yoshikawa, Hideki; Iijima, Kazuki; Hama, Katsuhiro; Iwatsuki, Teruki; et al.

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 20(1), p.3 - 14, 2013/06

https://doi.org/10.3327/jnuce.20.3

This paper shows a current status of groundwater colloids studies on the performance assessment of geological disposal of radioactive wastes in Japan, and summaries realistic approach of the colloids studies at a substantial research network for Japanese universities and institutes.

Journal Articles

Complexation of Am with size-fractionated soil humic acids

Nagao, Seiya*; Aoyama, Masakazu*; Watanabe, Akira*; Tanaka, Tadao

Colloids and Surfaces A; Physicochemical and Engineering Aspects, 347(1-3), p.239 - 244, 2009/09

https://doi.org/10.1016/j.colsurfa.2009.05.006

Times Cited Count：6 Percentile：14.06(Chemistry, Physical)

Humic substances play important role in geochemical behavior of trace elements such as actinides in aquatic environments. The association properties of Am with humic substances were studied on the basis of structural feature of humic substances. Humic acids prepared from three types of soils, and separated two humic acids with different structural features: fluorescence-poor and higher molecular size fraction, HA and fluorescence-rich and lower molecular size fraction, FL. The association experiments were carried out in a medium of 0.01M NaClO $_{4}$ solution at a humus concentration of 10 mg/l and pH 6-8. The dominant size fractions of Am in the presence of the HA were 450nm - 100k Daltons and 100k - 30k Daltons. On the other hand, Am was presented in the size of 30k - 10k Daltons in the FL. These results indicate that characteristics of size-fractionated humic acids are related association properties with Am.

Journal Articles

Operating experience of the J-PARC linac

Hasegawa, Kazuo; Asano, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; Ito, Takashi; Kobayashi, Tetsuya; Kondo, Yasuhiro; Namekawa, Yuya; Oguri, Hidetomo; Okoshi, Kiyonori; et al.

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.55 - 57, 2009/00

http://accelconf.web.cern.ch/accelconf/LINAC08/papers/mop004.pdf

The beam commissioning of the J-PARC linac started in November 2006 and 181 MeV acceleration was successfully achieved in January 2007. The linac has delivered beams to the 3 GeV Rapid Cycling Synchrotron for its commissioning, and then, the subsequent Main Ring Synchrotron and the neutron target commissioning. The linac uses a Cs-free LaB $_{6}$ -driven ion source and 20 units of 324 MHz klystrons. As of June 2008, the operation times are about 3,000 and 6,000 hours for the ion source and the RF source, respectively. The operating experience of the linac is described.

Journal Articles

Molecular size distribution of Pu in the presence of humic substances in river and groundwaters

Nagao, Seiya*; Sakamoto, Yoshiaki; Tanaka, Tadao; Rao, R. R.*

Journal of Radioanalytical and Nuclear Chemistry, 273(1), p.135 - 139, 2007/07

https://doi.org/10.1007/s10967-007-0724-x

Times Cited Count：3 Percentile：25.42(Chemistry, Analytical)

no abstracts in English

JAEA Reports

Announced document collection of the 1st Information Exchange Meeting on Radioactive Waste Disposal Research Network (Joint research)

Nakayama, Shinichi; Nagasaki, Shinya*; Inagaki, Yaohiro*; Oe, Toshiaki*; Sasaki, Takayuki*; Sato, Seichi*; Sato, Tsutomu*; Tanaka, Satoru*; Tochiyama, Osamu*; Nagao, Seiya*; et al.

JAEA-Conf 2007-003, 120 Pages, 2007/03

JAEA-Conf-2007-003.pdf:53.18MB

The 1st information exchange meeting on Radioactive Waste Disposal Research Network was held in Nuclear Science Research Institute of Japan Atomic Energy Agency on August 4, 2006. Radioactive Waste Disposal Research Network was established by under Interorganization Atomic Energy Research Program of Japan Atomic Energy Agency, and the objective is to bring both research infrastructures and human expertise in Japan to an adequate performance level, thereby contributing to the development of the fundamental research area in the field of radioactive waste disposal. This lecture material is a collection of research presentations and discussions during the information exchange meeting.

Journal Articles

PLC control of J-PARC low level RF system

Suzuki, Hiroyuki; Chishiro, Etsuji; Ito, Takashi; Kobayashi, Tetsuya; Hasegawa, Kazuo; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*; Fang, Z.*; Naito, Fujio*; et al.

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.513 - 515, 2007/00

no abstracts in English

Journal Articles

Acceleration cavity tuner controller noise measure

Suzuki, Hiroyuki; Chishiro, Etsuji; Ito, Takashi; Hasegawa, Kazuo; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*; Fang, Z.*; Naito, Fujio*; Tanaka, Hirokazu*

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.493 - 495, 2006/00

no abstracts in English

Journal Articles

Beam commissioning of the J-PARC linac DTL1 at KEK

Kondo, Yasuhiro; Akikawa, Hisashi; Anami, Shozo*; Asano, Hiroyuki*; Fukui, Yuji*; Igarashi, Zenei*; Ikegami, Kiyoshi*; Ikegami, Masanori*; Ito, Takashi; Kawamura, Masato*; et al.

Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.156 - 158, 2004/08

A commissioning of the J-PARC linac DTL1 is now under way at KEK. A 30mA H $^{-}$ beam was accelerated to 19.7-MeV, and 100% transmission was obtained with a 20-msec-pulse-width and 12.5-Hz-repetition beam. In this paper, present status of the DTL1 commissioning and preliminary results of the commissioning, such as emittance measurements, are presented.

Journal Articles

Sorption behavior of plutonium(IV) onto soils in the presence of humic acid

Tanaka, Tadao; Nagao, Seiya; Sakamoto, Yoshiaki; Ogawa, Hiromichi

Journal of Nuclear Science and Technology, 39(Suppl.3), p.524 - 527, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875522

Influence of humic acid on the sorption of Pu onto a coastal sand, which does not sorb humic acid, and an ando soil, which sorbs humic acid very well, was examined with respect to molecular sizes of humic acid. Sorption affinity of Pu for the coastal sand decreased with increasing humic acid concentration. As to the ando soil, the sorption affinity of Pu in the presence of humic acid was larger than that in the absence of humic acid, in low humic acid concentration range. These results suggest that apparent sorption affinity of Pu on the soils is dependent on the complexation ability with humic acid and the sorption affinity of the resulting humic complexes. Concentration profiles of Pu in each size fraction of solution before and after the sorption experiment were obtained by ultrafiltration technique. It was found that the complexation and sorption properties of humic acid are dependent on its molecular size and the important molecular size relating to the complexation and sorption properties tends to shift into smaller size ranges with increasing humic acid concentration.

Journal Articles

Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy of functional groups of humic acid dissolving in aqueous solution

Tanaka, Tadao; Nagao, Seiya; Ogawa, Hiromichi

Analytical Sciences (CD-ROM), 17(Suppl.), p.1081 - 1084, 2002/03

Structural information of humic acid dissolving in aqueous solution has been studied by ATR-FTIR spectroscopy. Two types of humic acid fractions were prepared: one is dominated by aliphatic structure and another is dominated with aromatic structure. The functional groups of both fractions have been characterized with respect to their ATR-FTIR spectral structures (ATR spectra) measured in pH range of 2 - 10. The ATR spectra were compared with the infrared spectra of the freeze-dried humic acid fractions, which were obtained using transmission Fourier transform infrared spectroscopy with KBr pellet (KBr spectra) and using diffuse reflectance infrared Fourier transform spectroscopy (DRS spectra). In a comparison between spectra obtained from the three infrared spectroscopic methods, the major absorptions of the ATR spectra for both fractions are in well agreement with those of the KBr spectra and the DRS spectra, each other. These show that the functional groups of the humic acid dissolving in aqueous solution could characterize by using the ATR-FTIR spectroscopy.

Journal Articles