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Ni from the (
,
) reactionElekes, Z.*; Kripk
, 
*; Sohler, D.*; Sieja, K.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; Baba, Hidetada*; et al.
Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01
Times Cited Count：10 Percentile：64.15(Physics, Nuclear)The nuclear structure of the Ni nucleus was investigated by (,) reaction using a NaI(Tl) array to detect the deexciting prompt 
rays. A new transition with an energy of 2227 keV was identified by 
and 
coincidences. Our shell-model calculations using the Lenzi, Nowacki, Poves, and Sieja interaction produced good candidates for the experimental proton hole states in the observed energy region, and the theoretical cross sections showed good agreement with the experimental values. Although we could not assign all the experimental states to the theoretical ones unambiguously, the results are consistent with a reasonably large Z = 28 shell gap for nickel isotopes in accordance with previous studies.
Sc and development of the 
subshell closureSteppenbeck, D.*; Takeuchi, Satoshi*; Aoi, Nori*; Doornenbal, P.*; Matsushita, Masafumi*; Wang, H.*; Baba, Hidetada*; Go, Shintaro*; Holt, J. D.*; Lee, J.*; et al.
Physical Review C, 96(6), p.064310_1 - 064310_10, 2017/12
Times Cited Count：18 Percentile：80.82(Physics, Nuclear)no abstracts in English
Ar and the 
=32 subshell closureSteppenbeck, D.*; Takeuchi, Satoshi*; Aoi, Nori*; Doornenbal, P.*; Matsushita, Masafumi*; Wang, H.*; Utsuno, Yutaka; Baba, Hidetada*; Go, Shintaro*; Lee, J.*; et al.
Physical Review Letters, 114(25), p.252501_1 - 252501_6, 2015/06
Times Cited Count：44 Percentile：87.83(Physics, Multidisciplinary)The neutron-rich nucleus Ar is produced by the fragmentation reactions of 
Ca, Sc, and 
Ti at the RIBF facility in RIKEN, and its deexcited rays are observed for the first time. The first 
level in Ar is identified to lie at 1178(18)keV from the most intense -ray spectra. This experimental data, together with the systematics of the levels for surrounding nuclei, is analyzed with large-scale shell-model calculations. Consequently, the 
sub-shell gap in Ar is equivalent to that of 
Ca, thus making the level in Ar higher than that of 
Ar. The shell-model calculation also predicts that the sub-shell gap enhances in going from Ca to Ar, which will be verified by forthcoming experiments for Ar.
O
(001) surface; A DFT studyMao, W.*; Chikada, Takumi*; Shimura, Kenichiro*; Suzuki, Akihiro*; Yamaguchi, Kenji; Terai, Takayuki*
Journal of Nuclear Materials, 443(1-3), p.555 - 561, 2013/11
Times Cited Count：3 Percentile：25.73(Materials Science, Multidisciplinary)In this work, 
calculations based on density functional theory (DFT) and generalized gradient approximation were performed to investigate the structural and electronic properties of the cubic Er
O
(001) surface and H adsorption processes on this surface. Several stable adsorption sites were identified, and at the most energetically favorable adsorption sites it was found that H bonds with O atoms at the cubic ErO (001) surface with an adsorption energy of 295.68 kJ mol
at coverage 1/8 ML, which was inclined to decrease with the increase of H coverage (
1/4 ML). In addition, the calculations revealed that the dissociative H atom configurations have adsorption energies that are at least 152.64 kJ mol greater than the H molecule configurations on the surface. These results are discussed in regard of the hydrogen isotope permeation behavior in the tritium permeation barrier in a fusion reactor.
CaSteppenbeck, D.*; Takeuchi, Satoshi*; Aoi, Nori*; Doornenbal, P.*; Matsushita, Masafumi*; Wang, H.*; Baba, Hidetada*; Fukuda, Naoki*; Go, Shintaro*; Homma, Michio*; et al.
Nature, 502(7470), p.207 - 210, 2013/10
Times Cited Count：285 Percentile：99.78(Multidisciplinary Sciences)no abstracts in English
Nishimura, Masahiro; Nagai, Keiichi; Onojima, Takamitsu; Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*
Journal of Nuclear Science and Technology, 49(1), p.71 - 77, 2012/01
Times Cited Count：4 Percentile：31.96(Nuclear Science & Technology)Oxidation in the early stage of sodium combustion is especially important regarding the aspect of reaction continuity. The purpose of this study is to understand the sodium reaction precisely in order to apply the knowledge of the sodium reaction to promoting further safety of FRs.
Nishimura, Masahiro; Kamide, Hideki; Otake, Shiro*; Sugiyama, Kenichiro*
Journal of Nuclear Science and Technology, 48(12), p.1420 - 1427, 2011/12
Times Cited Count：5 Percentile：38.65(Nuclear Science & Technology)The purpose of this study is to understand the oxidation behavior of liquid sodium in detail, because it plays an important role in the continuation of the combustion process. Understanding the role of the dendritic oxide in the reaction can be helpful for controlling sodium combustion phenomena, for example, the extinction process. Therefore, this study is a useful contribution to ensuring FR safety.
Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Otake, Shiro*
Proceedings of 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-8) (CD-ROM), 11 Pages, 2010/10
The purpose of this study is to understand oxidation behavior of sodium precisely for FR safety against sodium combustion. It was recognized that dendritic oxide took an important role for the combustion reaction such as supplying the sodium to the reaction interface. In this study, we proposed a mechanistic model of supplying liquid sodium through the dendritic oxide based on the observation result of the growing behavior of dendritic oxide during combustion. In this model we made an attention to the kinds of chemical compounds. The formation of sodium peroxides can provide the sodium supplying route in the dendritic oxide. On the other hand the formation of sodium monoxide will block sodium supplying. The kinds of chemical compounds were decided by the Gibbs's free energy of thermodynamics in the reaction field such as temperature and oxygen concentration. This mechanistic model can explain the oxidation behavior consistently with the observation results.
Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Otake, Shiro*
Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM), 12 Pages, 2008/10
Liquid sodium is used as the coolant of the fast reactor (FR), because of its high thermal conductivity and wide temperature range of liquid phase. It is superior as thermal medium, however the chemical reactivity with water and oxygen is very high. Hence FR plants have been taking safety measures for these reactions. After the "Monju" sodium leak accident, it is desired that more physical and chemical understanding of reaction phenomena and more mechanistic analysis for the sodium fire from the view point of public acceptance. The purpose of this study is to understand oxidation behavior of a liquid sodium droplet precisely, which is a fundamental reaction of spray fire and is easy to observe the reaction interface. This study is also useful for the establishment of safety criterion to handle the remained non-burning sodium after the accident. The oxidation of a liquid sodium droplet was visualized by using a simple experimental setup and a high speed video camera. A sodium single droplet of ca. 50 mg was made at the tip of a nozzle in a combustion chamber. The oxidation was started by supply of oxygen and nitrogen mixture gas. The initial temperature of sodium droplet and the oxygen fraction in the atmosphere were selected as experimental parameters. It was shown that columnar oxides grew longer as initial temperature of sodium droplet was lower and oxygen fraction was lower. In addition, it was observed that sodium combustion with an orange light emission started from the tip of columnar oxides grown out from the droplet surface. These observations suggest the existence of mechanism that liquid sodium is drawn up from droplet to reaction interface by the capillary force caused in the porous oxides which are formed on the droplet surface.
Shimura, Kenichiro*; Yamaguchi, Kenji; Terai, Takayuki*; Yamawaki, Michio*
Journal of Alloys and Compounds, 449(1-2), p.357 - 361, 2008/01
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)no abstracts in English
-FeSi prepared by ion beam sputter deposition (IBSD) methodZhuravlev, A. V.; Yamamoto, Hiroyuki; Shimura, Kenichiro*; Yamaguchi, Kenji; Shamoto, Shinichi; Hojo, Kiichi; Terai, Takayuki*
Thin Solid Films, 515(22), p.8149 - 8153, 2007/08
Times Cited Count：3 Percentile：17.87(Materials Science, Multidisciplinary)A semiconducting silicide, -FeSi, formed on a Si substrate, is known to exhibit strong photoluminescence (PL) peak at around 0.8 eV when it is annealed at high temperature (1073-1173 K). On the other hand, dislocation-related band of Si has intensity maxima at 0.81 eV. In the present study, the PL spectra were taken at the various stages of IBSD in order to understand the processes that are responsible for the observed PL enhancement. We observed a strong PL peak at around 0.8 eV in IBSD-grown -FeSi film on Si substrate, as well as in substrate itself, upon thermal annealing in air at 1153 K. The most pronounced peak at 0.8 eV was observed when Si substrates were sputter etched by Ne
, prior to the thermal annealing in air. However, the temperature dependence of peak intensity of -FeSi was different from that of SE-treated Si, where thermal quenching appeared to occur at slightly lower temperature in the former.
-FeSi thin film prepared by ion beam sputter deposition methodSasase, Masato*; Shimura, Kenichiro*; Yamaguchi, Kenji; Yamamoto, Hiroyuki; Shamoto, Shinichi; Hojo, Kiichi
Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.186 - 189, 2007/04
Times Cited Count：5 Percentile：40.96(Instruments & Instrumentation)Beta iron disilicide (-FeSi) is one of the candidate materials for a compound semiconductor. We have employed ion beam sputter deposition method to grow highly oriented -FeSi film on a single crystal Si(100) substrate. In the present study, sputter etching effect of the substrate is investigated by the cross-sectional transmission electron microscope (TEM) observation in order to observe nanostructural changes as a function of Ne energy. The observed TEM images show that the 1 keV sputtering provides uniform films with few defects and smooth interface. The number of the produced defects rapidly increases with the energy. The obtained -FeSi tends to form small grains at the higher energy. Quite rough surface is also observed in this condition. Higher energies produce excessive amount of damages for the substrate to form epitaxially grown film. These results imply that a certain fluence is required for better quality of the deposited film.
-FeSi/Si(100) prepared by ion beam sputter depositionSasase, Masato*; Shimura, Kenichiro*; Yamamoto, Hiroyuki; Yamaguchi, Kenji; Shamoto, Shinichi; Hojo, Kiichi
Japanese Journal of Applied Physics, Part 1, 45(6A), p.4929 - 4933, 2006/06
Times Cited Count：9 Percentile：34.33(Physics, Applied)no abstracts in English
-FeSi films on Si substrateYamaguchi, Kenji; Shimura, Kenichiro; Udono, Haruhiko*; Sasase, Masato*; Yamamoto, Hiroyuki; Shamoto, Shinichi; Hojo, Kiichi
Thin Solid Films, 508(1-2), p.367 - 370, 2006/06
Times Cited Count：12 Percentile：49.71(Materials Science, Multidisciplinary)no abstracts in English
-FeSi thin film fabricated on Si and SIMOX substrate by IBSD methodShimura, Kenichiro; Yamaguchi, Kenji; Sasase, Masato*; Yamamoto, Hiroyuki; Shamoto, Shinichi; Hojo, Kiichi
Vacuum, 80(7), p.719 - 722, 2006/05
Times Cited Count：9 Percentile：34.33(Materials Science, Multidisciplinary)no abstracts in English
-FeSi film prepared by ion beam sputter deposition (IBSD) methodSasase, Masato*; Yamamoto, Hiroyuki; Yamaguchi, Kenji; Shimura, Kenichiro
Zairyo Kaihatsu No Tameno Kenbikyoho To Oyo Shashinshu, P. 194, 2006/03
no abstracts in English
Aihara, Jun; Hojo, Kiichi; Furuno, Shigemi*; Shimura, Kenichiro; Hojo, Tomohiro*; Sawa, Kazuhiro; Yamamoto, Hiroyuki; Motohashi, Yoshinobu*
Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.441 - 444, 2006/01
Times Cited Count：1 Percentile：12.86(Instruments & Instrumentation)no abstracts in English
Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Shimura, Kenichiro
Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.469 - 472, 2006/01
Times Cited Count：3 Percentile：28.19(Instruments & Instrumentation)SiC/SiC composites are one of the candidate materials for first wall in a fusion reactor because of their high strength at high temperature and low residual radioactivity after irradiation. In the fusion reactor, these materials are required to have high thermal diffusivity for heat exchange and reducing the thermal shock. Under fusion conditions, helium (He) and hydrogen (H) are produced in SiC. In this study, the effect of He ions implantation on the thermal diffusivities of SiC and SiC/SiC composite were investigated. In the results, the thermal diffusivities of SiC and SiC/SiC composites decreased after He ions implantation. However, the thermal diffusivities of SiC and SiC/SiC composites hardly reduced in the operation temperature of fusion reactor. The thermal diffusivities of He implanted specimens were partly recovered by annealing. The defect concentration induced by He implantation, X
, in SiC/SiC composites was estimated. The X rapidly decreased around 500 
C. The reason is that the He release from SiC starts at 500 C.
-FeSi thin film prepared by ion beam sputter deposition methodShimura, Kenichiro; Yamaguchi, Kenji; Yamamoto, Hiroyuki; Sasase, Masato*; Shamoto, Shinichi; Hojo, Kiichi
Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.673 - 675, 2006/01
Times Cited Count：6 Percentile：43.85(Instruments & Instrumentation)no abstracts in English
-FeSi via dry processesShimura, Kenichiro; Yamaguchi, Kenji; Sasase, Masato*; Yamamoto, Hiroyuki; Shamoto, Shinichi; Hojo, Kiichi
Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.676 - 678, 2006/01
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)no abstracts in English
