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Journal Articles

Band gap formation in graphene by hybridization with Hex-Au(001) reconstructed surface

Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Vacuum and Surface Science, 66(9), p.525 - 530, 2023/09

As Au (001) surfaces exhibit a quasi-one-dimensional corrugated structure, Hex-Au(001), its periodicity was predicted to change the electronic structure of graphene when graphene was grown on this surface. Furthermore, the hybridization between graphene and Au is known to introduce bandgap and spin polarization into graphene. Here, we report angle-resolved photoemission spectroscopy and density functional theory calculation of graphene on a Hex-Au(001) surface. A bandgap of 0.2 eV in the graphene Dirac cone was observed at the crossing point of the graphene Dirac cone and Au 6sp bands, indicating that the origin of the bandgap formation was the hybridization between the graphene Dirac cone and Au 6sp band. We discussed the hybridization mechanism and anticipated spin injection into the graphene Dirac cone.

Journal Articles

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and Hydrogen Production Facility, 2; Development plan for coupling equipment between HTTR and Hydrogen Production Facility

Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; Noguchi, Hiroki; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 6 Pages, 2023/05

Journal Articles

Investigation of hydrogen superoxide adsorption during ORR on Pt/C catalyst in acidic solution for PEFC by ${it in-situ}$ high energy resolution XAFS

Yamamoto, Naoki*; Matsumura, Daiju; Hagihara, Yuto*; Tanaka, Kei*; Hasegawa, Yuta*; Ishii, Kenji*; Tanaka, Hirohisa*

Journal of Power Sources, 557, p.232508_1 - 232508_10, 2023/02

 Times Cited Count:0 Percentile:17.92(Chemistry, Physical)

Journal Articles

Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Physical Review Materials (Internet), 7(1), p.014002_1 - 014002_10, 2023/01

 Times Cited Count:0 Percentile:61.13(Materials Science, Multidisciplinary)

Au(001) surfaces exhibit a complex reconstructed structure [Hex-Au(001)] comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene-Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a Hex-Au(001) surface. The crossing point of the original and replica graphene $$pi$$ bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene $$pi$$ and Au $$6sp$$ bands, indicating that the bandgap is generated using hybridization of the graphene $$pi$$ and Au $$6sp$$ bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene $$pi$$ and Au $$6sp$$ would result in spin injection into graphene.

Journal Articles

Development of DynamicMC for PHITS Monte Carlo package

Watabe, Hiroshi*; Sato, Tatsuhiko; Yu, K. N.*; Zivkovic, M.*; Krstic, D.*; Nikezic, D.*; Kim, K. M.*; Yamaya, Taiga*; Kawachi, Naoki*; Tanaka, Hiroki*; et al.

Radiation Protection Dosimetry, 13 Pages, 2023/00

Previously, we have developed DynamicMC for modelling relative movement of ORNL phantom in a radiation field for MCNP. Using this software, 3-dimensional dose distributions in a phantom irradiated by a certain mono-energetic source can be deduced through its graphical user interface (GUI). In this study, we extended DynamicMC to be used in combination with the PHITS by providing it with a higher flexibility for dynamic movement for a less sophisticated anthropomorphic phantom. We anticipate that the present work and the developed open-source tools will be in the interest of nuclear radiation physics community for research and teaching purposes.

Journal Articles

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950$$^{circ}$$C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Journal Articles

Experimental investigation of the suppressed superconducting gap and double-resonance mode in Ba$$_{1-x}$$K$$_{x}$$Fe$$_{2}$$As$$_{2}$$

Ideta, Shinichiro*; Murai, Naoki; Nakajima, Masamichi*; Kajimoto, Ryoichi; Tanaka, Kiyohisa*

Physical Review B, 100(23), p.235135_1 - 235135_7, 2019/12

 Times Cited Count:2 Percentile:16.98(Materials Science, Multidisciplinary)

Journal Articles

Effect of water for the oxygen adsorption on surface of PtCo catalysts

Cui, Y.-T.*; Harada, Yoshihisa*; Niwa, Hideharu*; Oshima, Masaharu*; Hatanaka, Tatsuya*; Nakamura, Naoki*; Ando, Masaki*; Yoshida, Toshihiko*; Ishii, Kenji*; Matsumura, Daiju

NanotechJapan Bulletin (Internet), 11(4), 6 Pages, 2018/08

no abstracts in English

Journal Articles

Effect of electron correlations on spin excitation bandwidth in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ as seen via time-of-flight inelastic neutron scattering

Murai, Naoki; Suzuki, Katsuhiro*; Ideta, Shinichiro*; Nakajima, Masamichi*; Tanaka, Kiyohisa*; Ikeda, Hiroaki*; Kajimoto, Ryoichi

Physical Review B, 97(24), p.241112_1 - 241112_6, 2018/06

 Times Cited Count:5 Percentile:26.51(Materials Science, Multidisciplinary)

We use inelastic neutron scattering (INS) to investigate the effect of electron correlations on spin dynamics in iron-based superconductor Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$. Our INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A first principles analysis of dynamical spin susceptibility, incorporating the mass renormalization factor of 3, as determined by angle-resolved photoemission spectroscopy, provides a reasonable description of the observed spin excitations. This analysis shows that electron correlations in the Fe-3d bands yield enhanced effective electron masses, and consequently, induce substantial narrowing of the spin excitation bandwidth. Our results highlight the importance of electron correlations in an itinerant description of the spin excitations in iron-based superconductors.

Journal Articles

Upgrade and Replacement of Plant Dynamics Test Loop (PLANDTL)

Uchiyama, Naoki*; Ozawa, Tatsuya*; Sato, Koji*; Kobayashi, Jun; Onojima, Takamitsu; Tanaka, Masaaki

FAPIG, (194), p.12 - 18, 2018/02

no abstracts in English

Journal Articles

Design and application of greenhouse on the maintenance of analytical machineries in Tokai Reprocessing Plant

Suzuki, Yoshimasa; Tanaka, Naoki; Goto, Yuichi; Inada, Satoshi; Kuno, Takehiko

Nihon Hozen Gakkai Dai-14-Kai Gakujutsu Koenkai Yoshishu, p.385 - 389, 2017/08

Greenhouse is used in order to prevent diffusion of radioactive materials on the maintenance of machineries and decomposition of the analytical equipment such as glove box in Tokai Reprocessing Plant (TRP). The specifications of the greenhouse change depending on a risk of the radiation exposure, operation and environment. Design and application of original greenhouses in the analytical laboratory of TRP is summarized.

Journal Articles

Wetting induced oxidation of Pt-based nano catalysts revealed by ${{it in situ}}$ high energy resolution X-ray absorption spectroscopy

Cui, Y.-T.*; Harada, Yoshihisa*; Niwa, Hideharu*; Hatanaka, Tatsuya*; Nakamura, Naoki*; Ando, Masaki*; Yoshida, Toshihiko*; Ishii, Kenji*; Matsumura, Daiju; Oji, Hiroshi*; et al.

Scientific Reports (Internet), 7(1), p.1482_1 - 1482_8, 2017/05

 Times Cited Count:17 Percentile:48.51(Multidisciplinary Sciences)

Journal Articles

Electronic structure of Pt and Pt-Co nanoparticles with O$$_{2}$$ and O$$_{2}$$/H$$_{2}$$O adsorption revealed by in situ XAFS and hard X-ray photoelectron spectroscopy

Cui, Y.*; Harada, Yoshihisa*; Hatanaka, Tatsuya*; Nakamura, Naoki*; Ando, Masaki*; Yoshida, Toshihiko*; Ikenaga, Eiji*; Ishii, Kenji*; Matsumura, Daiju; Li, R.*; et al.

ECS Transactions, 72(8), p.131 - 136, 2016/10

 Times Cited Count:1 Percentile:49.39

Journal Articles

Restoration of the corrosion department of the reprocessing facilities analysis waste fluid plumbing

Nishida, Naoki; Suwa, Toshio; Tanaka, Naoki; Inada, Satoshi; Kuno, Takehiko

Nihon Hozen Gakkai Dai-11-Kai Gakujutsu Koenkai Yoshishu, p.121 - 126, 2014/07

Corroded pore was found at stainless pipe for liquid waste solution from the analytical laboratory. Part of the pipe was cut for preparing samples to investigate the cause of the corrosion. The same size of stainless pipe was welded to recover it, under the strict radiation control. The restoration work was done inside of the vinyl house, as it is called "greenhouse", which was the small room completely separated by vinyl sheet. All the works, cutting, decontamination, digging groove and welding with back seal gas, were done inside of the greenhouse. We report the work method for recovery of corroded pipe containing radioactive materials

Journal Articles

Investigation into corrosion cause of the reprocessing facilities analysis waste fluid plumbing

Tanaka, Naoki; Suwa, Toshio; Nishida, Naoki; Kuno, Takehiko; Inami, Shinichi

Nihon Hozen Gakkai Dai-11-Kai Gakujutsu Koenkai Yoshishu, p.127 - 131, 2014/07

Corroded pore was found at stainless pipe for liquid waste solution from the analytical laboratory. In order to find out the cause of corrosion, analytical samples were prepared cutting from the pipe. Reagents contained chloride, which had been used analytical laboratory more than ten years before the date, were found to be the trigger of the localized corrosion. We checked up all the pipes, which have been wasted including chloride solutions, by phased array instrument. We report the investigation of cause of corrosion and results of non-destructive testing.

Journal Articles

Observation of a $$p$$-wave one-neutron halo configuration on $$^{37}$$Mg

Kobayashi, Nobuyuki*; Nakamura, Takashi*; Kondo, Yosuke*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Barthelemy, R.*; Famiano, M. A.*; Fukuda, Naoki*; et al.

Physical Review Letters, 112(24), p.242501_1 - 242501_5, 2014/06

 Times Cited Count:83 Percentile:94.31(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Status of JAEA-AMS-MUTSU at 2010-2011

Kabuto, Shoji; Kinoshita, Naoki; Tanaka, Takayuki; Kuwabara, Jun; Seki, Takeo

Dai-24-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.9 - 12, 2011/07

A Tandetron Accelerator Mass Spectrometer (AMS) manufactured by High Voltage Engineering Europa in Netherlands had been set up at the Mutsu office of Aomori Research and Development Center, Japan Atomic Energy Agency (JAEA) in 1997. This AMS features 3 MV Tandetron accelerator and two independence beamlines for $$^{14}$$C and $$^{129}$$I measurement. In this report, we describe the summary of the current status at 2010-2011.

Journal Articles

Current status of $$^{14}$$C measurement at JAEA-AMS-MUTSU

Tanaka, Takayuki; Kabuto, Shoji; Kinoshita, Naoki; Seki, Takeo

Nagoya Daigaku Kasokuki Shitsuryo Bunsekikei Gyoseki Hokokusho, 22, p.169 - 173, 2011/03

An accelerator mass spectrometry at Mutsu office, Japan Atomic Energy Agency (JAEA AMS MUTSU) was established in 1997 and the routine operation of radiocarbon measurement was started from 1999. The radiocarbon was measured by 1,053 samples in 2010, and the number of radiocarbon measurements reached 10,342 samples since the routine operation. This AMS has adopted the open door policy for the general users from the fiscal year of 2006 and various researches have been in progress by many users. In this presentation, I introduce the current status of JAEA AMS MUTSU.

Journal Articles

Status of JAEA-AMS-MUTSU

Tanaka, Takayuki; Kabuto, Shoji; Kinoshita, Naoki; Suzuki, Takashi; Kuwabara, Jun; Seki, Takeo

Dai-13-Kai AMS Shimpojiumu Hokokusho, p.129 - 132, 2011/01

An accelerator mass spectrometry at Aomori Research and Development Center, JAEA (JAEA-AMS-MUTSU) was established in 1997 and the routine operation of $$^{14}$$C and $$^{129}$$I measurement was started from 1999 and 2003, respectively. This AMS has adopted the open door policy for the general users from the fiscal year of 2006 and various researches have been in progress by many users. In this presentation, we introduce the status of JAEA-AMS-MUTSU. The total number of measurements has increased well for five years after the open door policy excluding in 2008. The reasons for the decrease in 2008 were that we had stopped the operation of AMS for about one and half months because the operation system of AMS was upgraded, and that we could not measure the $$^{14}$$C for several months because the amplifier of detector had broken. We had resolved this trouble and our AMS can measure smoothly both $$^{14}$$C and $$^{129}$$I.

Journal Articles

Determination of trace amounts of plutonium in low-active liquid wastes from spent nuclear-fuel reprocessing plants by flow injection-based solid-phase extraction/electrochemical detection system

Taguchi, Shigeo; Yamamoto, Masahiko; Surugaya, Naoki; Kurosawa, Akira; Hiyama, Toshiaki; Tanaka, Tatsuhiko*

Journal of Radioanalytical and Nuclear Chemistry, 288(2), p.435 - 441, 2011/01

 Times Cited Count:6 Percentile:44.59(Chemistry, Analytical)

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