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Journal Articles

Factors controlling $$^{134}$$Cs activity concentrations in sediment collected off the coast of Fukushima Prefecture in 2013-2015

Fukuda, Miho*; Aono, Tatsuo*; Yamazaki, Shinnosuke*; Ishimaru, Takashi*; Kanda, Jota*; Nishikawa, Jun*; Otosaka, Shigeyoshi

Geochemical Journal, 52(2), p.201 - 209, 2018/00

 Times Cited Count:3 Percentile:16.86(Geochemistry & Geophysics)

To elucidate recent activity levels and the behavior of radiocesium in the coast off Fukushima Prefecture, lateral and vertical distributions of $$^{134}$$Cs in sediment were observed in 2013-2015 at 12 monitoring stations. At stations around the water depth of 100 m, relatively higher $$^{134}$$Cs activities were observed from surface sedimentary layer (0-3 cm). In these stations, sediments had high content of silt to clay particles and organic matter. The high $$^{134}$$Cs activities in the surface sediments were attributed to accumulation of highly mobile sediment particles. In October 2014, at some coastal stations, sharp peaks of $$^{134}$$Cs activities were observed in the subsurface (5-16 cm) sediments, whereas such broad peaks were not found in October 2015. These results suggest that the $$^{134}$$Cs activities in sediment had largely changed by lateral transport and re-sedimentation on the surface, as well as sediment mixing in the middle-layers.

Journal Articles

Dissolved radiocaesium in seawater off the coast of Fukushima during 2013-2015

Fukuda, Miho*; Aono, Tatsuo*; Yamazaki, Shinnosuke*; Nishikawa, Jun*; Otosaka, Shigeyoshi; Ishimaru, Takashi*; Kanda, Jota*

Journal of Radioanalytical and Nuclear Chemistry, 311(2), p.1479 - 1484, 2017/02

 Times Cited Count:5 Percentile:44.94(Chemistry, Analytical)

In order to investigate processes affecting distribution of radiocaesium in seawater in the adjacent region of Fukushima Daiichi Nuclear Power Plant (FDNPP), relationships between $$^{137}$$Cs activity in seawater and physical properties of seawater (salinity, temperature, and potential density) were observed in seven stations within 10 km radius from the FDNPP. As a whole, $$^{137}$$Cs concentrations in seawater were higher in the vicinity of the FDNPP, and were negatively correlated with potential density. From these results, it can be considered that river water discharge or export of seawater from the FDNPP's harbor has affected the higher activity levels of $$^{137}$$Cs in seawater. It was also observed that the $$^{137}$$Cs-elevated seawater can be advected to the 20$$sim$$50 m depths.

Journal Articles

Development of magnetic sensors for JT-60SA

Takechi, Manabu; Matsunaga, Go; Sakurai, Shinji; Sasajima, Tadayuki; Yagyu, Junichi; Hoshi, Ryo*; Kawamata, Yoichi; Kurihara, Kenichi; JT-60SA Team; Nishikawa, T.*; et al.

Fusion Engineering and Design, 96-97, p.985 - 988, 2015/10

 Times Cited Count:9 Percentile:64.82(Nuclear Science & Technology)

Journal Articles

Development of a turbo-molecular pump with a magnetic shield function

Ogiwara, Norio; Yanagibashi, Toru; Hikichi, Yusuke; Nishikawa, Masaaki; Kamiya, Junichiro; Wada, Kaoru*

Vacuum, 98, p.18 - 21, 2013/12

 Times Cited Count:6 Percentile:30.83(Materials Science, Multidisciplinary)

Journal Articles

Vacuum chamber made of soft magnetic material with high permeability

Kamiya, Junichiro; Ogiwara, Norio; Nishikawa, Masaaki; Hikichi, Yusuke; Yanagibashi, Toru; Kinsho, Michikazu

Vacuum, 98, p.12 - 17, 2013/12

 Times Cited Count:9 Percentile:38.1(Materials Science, Multidisciplinary)

One of the reasons of a beam loss in a high power accelerator is leakage magnetic field from a magnet at a close beam line, which distorts the beam orbit and makes the beam hit the wall of the beam pipe. The most effective way to shield such leakage field is to cover the beam by the magnetic materials at the nearest space. This means that vacuum chambers should be made of the magnetic materials. We selected the permalloy, which has very high magnetic permeability for such a magnetic material. However, there is not proven evidence of the vacuum chambers, which are made of magnetic materials. We have developed a vacuum chamber of such new material with the object of vacuum and magnetic characteristics.

Journal Articles

Reduction of outgassing from the ferrite cores in the kicker magnet of J-PARC 3-GeV rapid cycling synchrotron

Ogiwara, Norio; Suganuma, Kazuaki; Hikichi, Yusuke; Nishikawa, Masaaki; Yanagibashi, Toru; Kamiya, Junichiro; Kinsho, Michikazu

Journal of the Vacuum Society of Japan, 56(5), p.159 - 162, 2013/05

Journal Articles

Electroplating of Ni microstructures on the cross section of Cu wire using PMMA mother fabricated by proton beam writing

Tanabe, Yusuke*; Iwamoto, Takashi*; Takahashi, Junichi*; Nishikawa, Hiroyuki*; Sato, Takahiro; Ishii, Yasuyuki; Kamiya, Tomihiro

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 129, 2013/01

Journal Articles

Status of the vacuum system in J-PARC RCS

Kamiya, Junichiro; Ogiwara, Norio; Nishikawa, Masaaki; Hikichi, Yusuke; Yanagibashi, Toru; Kinsho, Michikazu

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.2522 - 2524, 2012/05

In the vacuum system of J-PARC Rapid cycling synchrotron (RCS), we use beam pipes and bellows whose materials are vacuum fired at 700$$sim$$850 $$^{circ}$$C in order to eliminate atoms in their bulk who are origin of outgassing. Until now, beam power has been increased up to 300 kW. Pressure in synchrotron beam line increased when the high power beam was accelerated. However, increment of pressure has reduced during the continuous beam operation. It is because the molecules, which adsorb on surface of the wall of the vacuum chambers, desorb by an ion bombardment and a heat generation due to an eddy current. Because the atoms in the bulk is eliminated, desorption of the molecules, which adsorb on the surface, means the reduction of the outgassing from the wall. In this presentation, we will report the past situation of the vacuum system during the beam operation. In addition, we also show the status after the Great East Japan Earthquake.

Journal Articles

Reduction of outgassing from the ferrite cores in the kicker magnet of J-PARC RCS

Ogiwara, Norio; Suganuma, Kazuaki; Hikichi, Yusuke; Nishikawa, Masaaki; Yanagibashi, Toru; Kamiya, Junichiro; Kinsho, Michikazu

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.487 - 489, 2012/05

Journal Articles

Development of an in-situ bake-out method for outgassing reduction of kicker ferrite cores

Kamiya, Junichiro; Ogiwara, Norio; Nishikawa, Masaaki; Hikichi, Yusuke; Yanagibashi, Toru; Suganuma, Kazuaki

Journal of the Vacuum Society of Japan, 55(4), p.156 - 159, 2012/04

It is usually difficult to reduce outgassing of a large structure inside a vacuum chamber by baking the whole chamber, which causes the large extension of the chamber and needs a lot of heater power. The solution is to rise the temperature of structure object without heating the vacuum chamber. This means to install heat source inside the chamber and increase the heat quantity to the object by inserting the heat shield between the object and the chamber. In the particle accelerator field, there are a lot of such requirements for reducing outgassing of structures inside vacuum chambers. One example is a kicker magnet, which is installed in a vacuum chamber and consists mainly of ferrite cores and aluminum electric plates. We applied the above method to the outgassing reduction of the kicker. In this article, we show outline of this in-situ bake-out method, the effects of the heat shield on the heat quantity and the result of the outgassing reduction.

Journal Articles

Fabrication of nanowires by varying energy microbeam lithography using heavy ions at the TIARA

Kamiya, Tomihiro; Takano, Katsuyoshi; Ishii, Yasuyuki; Sato, Takahiro; Oikawa, Masakazu*; Okubo, Takeru; Haga, Junji*; Nishikawa, Hiroyuki*; Furuta, Yusuke*; Uchiya, Naoyuki*; et al.

Nuclear Instruments and Methods in Physics Research B, 267(12-13), p.2317 - 2320, 2009/06

 Times Cited Count:7 Percentile:47.19(Instruments & Instrumentation)

Journal Articles

Development of micromachining technology in ion microbeam system at TIARA, JAEA

Kamiya, Tomihiro; Nishikawa, Hiroyuki*; Sato, Takahiro; Haga, Junji; Oikawa, Masakazu*; Ishii, Yasuyuki; Okubo, Takeru; Uchiya, Naoyuki; Furuta, Yusuke*

Applied Radiation and Isotopes, 67(3), p.488 - 491, 2009/03

 Times Cited Count:4 Percentile:30.6(Chemistry, Inorganic & Nuclear)

Development of a mask-less ion beam lithography technique for fabricating micro- or nano-meter sized structures has been started at the microbeam systems in the ion accelerator facility of JAEA Takasaki (TIARA) in collaboration with Shibaura Institute of Technology. In order to obtain a high precision measure for microbeam size estimation and lens system optimization, or for improvement of spatial resolution down to 100 nm level, we applied this lithography technique itself combined with the electroplating process to make a Ni relief pattern as an optimum resolution standard to be used in secondary electron imaging. In this work, using this standard, the smallest beam size could be obtained. This paper also discuses on the scattering of ions in the materials influenced to the resolution using a Monte Carlo simulation code.

Journal Articles

Ni electroplating on a resist micro-machined by proton beam writing

Uchiya, Naoyuki*; Furuta, Yusuke*; Nishikawa, Hiroyuki*; Watanabe, Toru*; Haga, Junji; Sato, Takahiro; Oikawa, Masakazu; Ishii, Yasuyuki; Kamiya, Tomihiro

Microsystem Technologies, 14(9-11), p.1537 - 1540, 2008/10

 Times Cited Count:17 Percentile:64.39(Engineering, Electrical & Electronic)

Journal Articles

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

 Times Cited Count:51 Percentile:71.37(Biochemistry & Molecular Biology)

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

Journal Articles

Retention of hydrogen isotopes in divertor tiles used in JT-60U

Hirohata, Yuko*; Shibahara, Takahiro*; Tanabe, Tetsuo*; Oya, Yasuhisa*; Arai, Takashi; Goto, Yoshitaka*; Masaki, Kei; Yagyu, Junichi; Oyaizu, Makoto*; Okuno, Kenji*; et al.

Fusion Science and Technology, 48(1), p.557 - 560, 2005/07

 Times Cited Count:3 Percentile:24.27(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Anisotropy of resonant inelastic X-ray scattering at the $$K$$ edge of Si; Theoretical analysis

Nishikawa, Yunori; Usuda, Manabu; Igarashi, Junichi*

Journal of the Physical Society of Japan, 73(11), p.3171 - 3176, 2004/11

 Times Cited Count:3 Percentile:26.48(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Resonant inelastic X-ray scattering at the K edge of Ge

Nishikawa, Yunori; Usuda, Manabu; Igarashi, Junichi*; Shoji, Hironobu*; Iwazumi, Toshiaki*

Journal of the Physical Society of Japan, 73(4), p.970 - 975, 2004/04

 Times Cited Count:6 Percentile:41.22(Physics, Multidisciplinary)

no abstracts in English

Oral presentation

Micro-machining of resist on silicon by proton beam writing

Uchiya, Naoyuki*; Harada, Takuya*; Nishikawa, Hiroyuki*; Haga, Junji; Sakai, Takuro; Sato, Takahiro; Ishii, Yasuyuki; Kamiya, Tomihiro

no journal, , 

no abstracts in English

Oral presentation

Micro-machining of resist materials using MeV proton microbeams

Uchiya, Naoyuki*; Harada, Takuya*; Murai, Masato*; Nishikawa, Hiroyuki*; Haga, Junji; Sato, Takahiro; Oikawa, Masakazu*; Sakai, Takuro; Ishii, Yasuyuki; Fukuda, Mitsuhiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Production of 3-D resit structures on silicon plates by a proton beam writing technique

Furuta, Yusuke*; Uchiya, Naoyuki*; Nishikawa, Hiroyuki*; Haga, Junji; Oikawa, Masakazu*; Sato, Takahiro; Ishii, Yasuyuki; Kamiya, Tomihiro

no journal, , 

no abstracts in English

30 (Records 1-20 displayed on this page)