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Amekura, Hiroshi*; Toulemonde, M.*; Narumi, Kazumasa*; Li, R.*; Chiba, Atsuya*; Hirano, Yoshimi*; Yamada, Keisuke*; Yamamoto, Shunya*; Ishikawa, Norito; Okubo, Nariaki; et al.
Scientific Reports (Internet), 11(1), p.185_1 - 185_11, 2021/01
Times Cited Count：12 Percentile：75.03(Multidisciplinary Sciences)We report the track formation of 10 nm in diameter in silicon irradiated with 6 MeV C
, i.e., much lower energy than the previously reported energy threshold.
Ho, D. M. L.*; Nelwamondo, A. N.*; Okubo, Ayako; Rameb
ck, H.*; Song, K.*; Han, S.-H.*; Hancke, J. J.*; Holmgren, S.*; Jonsson, S.*; Kataoka, Osamu; et al.
Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.353 - 363, 2018/02
Times Cited Count：2 Percentile：20.93(Chemistry, Analytical)The Fourth Collaborative Material Exercise (CMX-4) of the Nuclear Forensics International Technical Working Group (ITWG) registered the largest participation for this exercise in nuclear forensics, with seven of the 17 laboratories participating for the first time. In this paper, participants from five of the first-time laboratories shared their individual experience in this exercise, from preparation to analysis of samples. The exercise proved to be highly useful for testing procedures, repurposing established methods, exercising skills, and improving the understanding of nuclear forensic signatures and their interpretation trough the post-exercise review meeting.
Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Ramebck, H.*; Nelwamondo, A. N.*; Kotze, D.*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 315(2), p.425 - 434, 2018/02
Times Cited Count：14 Percentile：81.7(Chemistry, Analytical)In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the 
U-
Pa and 
U-
Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions.
Adhi, P. M.*; Okubo, Nariaki; Komatsu, Atsushi; Kondo, Masatoshi*; Takahashi, Minoru*
Energy Procedia, 131, p.420 - 427, 2017/12
Times Cited Count：0 Percentile：0.03(Energy & Fuels)The ionic conductivity of solid electrolyte may insufficient, and the sensor output signal will deviate from the theoretical one in low temperature. The performance of oxygen sensor with Ag/air reference electrode (RE) and liquid Bi/Bi
O
RE was tested in low-temperature LBE at 300
450
C and the charge transfer reactions impedance at the electrode-electrolyte interface was analyzed by electrochemical impedance analysis (EIS). After steady state condition, both of the sensors performed well and can be used at 300450C. Bi/Bi/BiO RE has lower impedance than Ag/air RE. Therefore, the response time of the oxygen sensor with Bi/Bi/BiO RE is faster than the oxygen sensor with Ag/air RE in the low-temperature region.
Amekura, Hiroshi*; Sele, M. L.*; Ishikawa, Norito; Okubo, Nariaki
Nanotechnology, 23(9), p.095704_1 - 095704_7, 2012/03
Times Cited Count：13 Percentile：48.92(Nanoscience & Nanotechnology)The degree of shape elongation was evaluated at room temperature (RT) by two different optical methods for solid Zn and V nanoparticles. The melting of NPs is not the key factor for the recovery to the spherical shape.
Hirose, Takanori; Okubo, Nariaki; Tanigawa, Hiroyasu; Ando, Masami; Sokolov, M. A.*; Stoller, R. E.*; Odette, G. R.*
Journal of Nuclear Materials, 417(1-3), p.108 - 111, 2011/10
Times Cited Count：18 Percentile：78.83(Materials Science, Multidisciplinary)This paper summarizes recent results of the irradiation experiments focused on F82H and its modified steels irradiated at 573 K. The materials used in this research were F82H-IEA and its modified steels. Post irradiation mechanical tests revealed that irradiation hardening of F82H is saturated by 9 dpa and the as-irradiated proof stress is less than 1 GPa. The deterioration of total elongation was also saturated by 9 dpa. Irradiation response of F82H-mod3, which is stable to temperature instability during material production and HIP treatment, was very similar to that of F82H-IEA, and negative impacts of extra tantalum was not observed. Therefore it can be an attractive option for the structural materials for blanket components manufactured by HIP.
Okubo, Nariaki; Sokolov, M. A.*; Tanigawa, Hiroyasu; Hirose, Takanori; Jitsukawa, Shiro; Sawai, Tomotsugu; Odette, G. R.*; Stoller, R. E.*
Journal of Nuclear Materials, 417(1-3), p.112 - 114, 2011/10
Times Cited Count：10 Percentile：60.88(Materials Science, Multidisciplinary)Irradiation hardening and fracture toughness of reduced-activation ferritic/martensitic steel F82H after irradiation were investigated with a focus on changing the fracture toughness transition temperature as a result of several heat treatments. The specimens were standard F82H-IEA (IEA), F82H-IEA with several heat treatments (Mod1 series) and a higher tantalum containing (0.1%) heat of F82H (Mod3). The specimens were irradiated up to 18 dpa at 300 C in High Flux Isotope Reactor under a collaborative research program between JAEA/US-DOE. The results of hardness tests showed that irradiation hardening of IEA was comparable with that of Mod3. However, the fracture toughness transition temperature of Mod3 was lower than that of IEA. The transition temperature of Mod1 was also lower than that of the IEA heat. These results suggest that tightening of specifications on the heat treatment condition and modification of the minor alloying elements seem to be effective to reduce the fracture toughness transition temperature after irradiation.
Amekura, Hiroshi*; Ishikawa, Norito; Okubo, Nariaki; Ridgway, M.*; Giulian, R.*; Mitsuishi, Kazuki*; Nakayama, Yoshiko*; Buchal, C.*; Mantl, S.*; Kishimoto, Naoki*
Physical Review B, 83(20), p.205401_1 - 205401_10, 2011/05
Times Cited Count：35 Percentile：78.45(Materials Science, Multidisciplinary)Elongation of metal nanoparticles (NPs) embedded in silica induced by swift heavy-ion irradiation, from spheres to spheroids, has been evaluated at low fluences by linearly polarized optical absorption spectroscopy. It is important to clarify whether the high fluences, i.e., track overlaps, are essential for the elongation. Zn NPs embedded in silica were irradiated with 200-MeV Xe ions. The comparison with numerical simulation suggested that the elongation of Zn NPs was induced by nonoverlapping ion tracks.
Hirose, Takanori; Okubo, Nariaki; Tanigawa, Hiroyasu; Kato, Yutai*; Clark, A. M.*; McDuffee, J. L.*; Heatherly, D. W.*; Stoller, R. E.*
DOE/ER-0313/49, p.94 - 99, 2010/12
Kishimoto, Maki; Katagiri, Masaki; Nakamura, Tatsuya; Okubo, Masataka*; Ukibe, Masahiro*; Kurakado, M.*; Kanno, Ikuo*; Fukuda, Daiji*; Takahashi, Hiroyuki*; Kraus, H.*; et al.
Nuclear Instruments and Methods in Physics Research A, 444(1-2), p.124 - 128, 2000/04
Times Cited Count：4 Percentile：36.74(Instruments & Instrumentation)no abstracts in English
Ando, T.; Nakamura, H.; Yoshida, H.; Sunaoshi, H.; Arai, T.; Akino, N.; Hiroki, S.; Yamamoto, Masahiro; Okubo, Minoru; Shimizu, M.*; et al.
Proc. 14th Symp. on Fusion Technology, 1986, Vol.1, p.615 - 620, 1987/00
no abstracts in English
Kudo, H.*; Okubo, M.*; Kondo, Y.*; Takai, S.*; Shibata, Y.*; Nagano, H.*; Kudo, Takeo*; Minami, T.*; Okazaki, T.*; Yoshikawa, O.*; et al.
PNC TJ104 79-01, 116 Pages, 1979/02
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