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Journal Articles

Newly found fault outcrops of the Tsuruga fault in the Mihama Town, Fukui Prefecture, Japan

Tateishi, Ryo*; Shimada, Koji; Iwamori, Akiyuki*; Wada, Shinya*; Seno, Shotaro*; Nagata, Ken*

Chishitsugaku Zasshi (Internet), 128(1), p.63 - 64, 2022/04

The Tsuruga Fault is an active right-lateral strike-slip fault that is about 20 km in length and distributed in the northeast-southwest direction from the eastern part of Tsuruga City to the southern part of Mihama Town, Fukui Prefecture. The Tsuruga fault borders the Jurassic accretionary complex (mixed rock) and the late Cretaceous granite around the Oritodani area in the Shinjo district of Mihama-cho. Lateral bendings of valleys along the fault in this area are clear geomorphological signatures of fault activity. We briefly report newly found multiple fault outcrops at these bending points with photos of them. This research is the result of joint research by Kansai Electric Power Company, University of Toyama, and JAEA.

Journal Articles

Investigation of main radiation source above shield plug of Unit 3 at Fukushima Daiichi Nuclear Power Station

Hirayama, Hideo*; Kondo, Kenjiro*; Suzuki, Seishiro*; Tanimura, Yoshihiko; Iwanaga, Kohei*; Nagata, Hiroshi*

EPJ Web of Conferences, 153, p.08010_1 - 08010_3, 2017/09

 Times Cited Count:2 Percentile:77.83(Nuclear Science & Technology)

Pulse height distributions were measured using a CdZnTe detector inside a lead collimator to investigate main source producing high dose rates above the shield plugs of Unit 3 at Fukushima Daiichi Nuclear Power Station. It was confirmed that low energy photons are dominant. Concentrations of Cs-137 under 60 cm concrete of the shield plug were estimated to be between 8.1$$times$$10$$^9$$ and 5.7$$times$$10$$^{10}$$ Bq/cm$$^2$$ from the measured peak count rate of 0.662 MeV photons. If Cs-137 was distributed on the surfaces of the gaps of the shied plugs with radius 6 m and with the averaged concentration of 5 points, 2.6$$times$$10$$^{10}$$ Bq/cm$$^2$$, total amount of Cs-137 is estimated to be 30 PBq.

Journal Articles

Root endophytic bacteria of a $$^{137}$$Cs and Mn accumulator plant, ${{it Eleutherococcus sciadophylloides}}$, increase $$^{137}$$Cs and Mn desorption in the soil

Yamaji, Keiko*; Nagata, Satoshi*; Haruma, Toshikatsu*; Onuki, Toshihiko; Kozaki, Tamotsu*; Watanabe, Naoko*; Namba, Kenji*

Journal of Environmental Radioactivity, 153, p.112 - 119, 2016/03

 Times Cited Count:20 Percentile:54.26(Environmental Sciences)

Of the 463 strains that we isolated, 107 (23.1%) produced the siderophores. We found $$^{137}$$Cs and Mn desorption concomitant with Al and Fe desorption. These results suggest that root endophytes of $$^{137}$$Cs accumulator plant produce siderophores, resulting in the desorption of $$^{137}$$Cs from the contaminated soil collected at Fukushima, Japan.

Journal Articles

Observation of momentum-resolved charge fluctuations proximate to the charge-order phase using resonant inelastic X-ray scattering

Yoshida, Masahiro*; Ishii, Kenji; Naka, Makoto*; Ishihara, Sumio*; Jarrige, I.*; Ikeuchi, Kazuhiko*; Murakami, Yoichi*; Kudo, Kazutaka*; Koike, Yoji*; Nagata, Tomoko*; et al.

Scientific Reports (Internet), 6, p.23611_1 - 23611_8, 2016/03

 Times Cited Count:1 Percentile:11.35(Multidisciplinary Sciences)

Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:20 Percentile:83.66(Materials Science, Multidisciplinary)

Journal Articles

Local structure analysis of Bi$$_{0.5}$$Na$$_{0.5}$$TiO$$_3$$

Yoneda, Yasuhiro; Nagata, Hajime*; Takenaka, Tadashi*

Journal of the Korean Physical Society, 66(9), p.1339 - 1343, 2015/05

 Times Cited Count:5 Percentile:40.3(Physics, Multidisciplinary)

The potential lead-free piezoelectric material bismuth sodium titanate, Bi$$_{0.5}$$Na$$_{0.5}$$TiO$$_3$$ (BNT), was investigated by means of high-energy synchrotron X-ray diffraction. BNT has been assumed thus far to exhibit the rhombohedral space group $$R3c$$ at room temperature. Recently, the average structure of BNT was described by the monoclinic space group $$Cc$$. We performed local structure analysis of BNT using atomic pair-distribution function method. The ground state of BNT was found to be rhombohedral structure in which bismuth and sodium atoms were chemically ordered in the perovskite ${it A}$-site.

Journal Articles

Local structure analysis of Nb-related perovskite materials

Yoneda, Yasuhiro; Kohara, Shinji*; Nagata, Hajime*; Fu, D.*; Takenaka, Tadashi*

Transactions of the Materials Research Society of Japan, 39(4), p.455 - 458, 2014/12

NaNbO$$_3$$, KNbO$$_3$$, and AgNbO$$_3$$ have rhombohedral structure at low temperatures. The phase transition depends on ${it A}$-site ion with NbO$$_6$$ octahedron. NaNbO$$_3$$ and KNbO$$_3$$ have structural phase transition from rhombohedral to orthorhombic with increasing temperature. On the other hand, the phase transition of AgNbO$$_3$$ occurs from rhombohedral to monoclinic. Since the rhombohedral structure is a highly ordered average structure, it tends to be subject to the influence of local randomness. We performed local structure analysis by using atomic pair-distribution function (PDF). The Nb-O bond clearly appeared in the observed distribution for NaNbO$$_3$$, but degraded in that for AgNbO$$_3$$. The difference of local structures causes different successive phase transitions for the Nb-related perovskite materials.

Journal Articles

Development of divertor simulation research in the GAMMA 10/PDX tandem mirror

Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

Journal Articles

Magnetic properties of R$$_{2}$$Fe$$_{3}$$O$$_{7}$$ (R=Yb and Lu)

Yoshii, Kenji; Ikeda, Naoshi*; Fukuyama, Ryota*; Nagata, Tomoko*; Kambe, Takashi*; Yoneda, Yasuhiro; Fukuda, Tatsuo; Mori, Shigeo*

Solid State Communications, 173, p.34 - 37, 2013/11

 Times Cited Count:4 Percentile:20.45(Physics, Condensed Matter)

We have investigated the magnetic properties of R$$_{2}$$Fe$$_{3}$$O$$_{7}$$ (R=Yb and Lu), which belongs to the homologous family of electronic ferroelectric RFe$$_{2}$$O$$_{4}$$. Magnetization measurements show ferrimagnetic ordering at the Neel temperature (T$$_{N}$$) of about 270 K, which is slightly higher than that of RFe$$_{2}$$O$$_{4}$$ (T$$_{N}$$ about 230-250 K). Observation of spin glass and exchange bias shows a coexistence of ferromagnetic and antiferromagneticinteractions, similarly to RFe$$_{2}$$O$$_{4}$$. This situation gives rise to a complex magnetic change and a broad peak of magnetic entropy change. Some characteristics, such as refrigeration temperatures higher than in RFe$$_{2}$$O$$_{4}$$, seem to offer a possibility of this system to applications.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 3

Kimura, Nobuaki; Takemoto, Noriyuki; Nagata, Hiroshi; Kimura, Akihiro; Naka, Michihiro; Nishikata, Kaori; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; et al.

KURRI Progress Report 2011, P. 219, 2012/10

In research reactors, a CCD camera is used to observe reactor core for reactor operation management, e.g. to prevent debris falling. In order to measure the reactor power and fuel burnup exactly by means of observation of Cherenkov light and $$gamma$$ ray information, the development of the on-line measurement device has been started since 2009. In this study, as a part of development of in-reactor surveillance, wavelength and absolute irradiance of Cherenkov light were measured by spectroscopy, and Cherenkov light was observed by the CCD camera. The neutral density filters (ND-filters) were used to investigate the transmittance of Cherenkov light in these measurements.

Journal Articles

Exchange bias in multiferroic $$R$$Fe$$_{2}$$O$$_{4}$$ ($$R$$=Y, Er, Tm, Yb, Lu and In)

Yoshii, Kenji; Ikeda, Naoshi*; Nishihata, Yasuo; Maeda, Daisuke*; Fukuyama, Ryota*; Nagata, Tomoko*; Kano, Jun*; Kambe, Takashi*; Horibe, Yoichi*; Mori, Shigeo*

Journal of the Physical Society of Japan, 81(3), p.033704_1 - 033704_4, 2012/03

 Times Cited Count:10 Percentile:55.26(Physics, Multidisciplinary)

Exchange bias (EB) behavior has been observed for multiferroic $$R$$Fe$$_{2}$$O$$_{4}$$ ($$R$$=Y, Er, Tm, Yb, Lu and In). The materials with the small $$R$$$$^{3+}$$ ions ($$R$$=Tm, Yb, Lu and In) exhibit large EB fields ($$_sim^{>}$$ 1 kOe) below $$sim$$100-150 K. This property is rooted in a magnetically glassy state, arising from the competition between ferro- and antiferromagnetic domain interactions. In addition, the exchange bias field tends to be more enhanced for smaller $$R$$$$^{3+}$$ ions. Hence, the EB is controlled by the substitution at the $$R$$-site in this series.

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 Times Cited Count:29 Percentile:73.24(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:184 Percentile:99.45(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03

 Times Cited Count:177 Percentile:98.48(Astronomy & Astrophysics)

The PHENIX experiment at RHIC has measured the invariant differential cross section for production of $$K^0_s$$, $$omega$$, $$eta'$$ and $$phi$$ mesons in $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, $$n$$ and $$T$$, determining the high $$p_T$$ and characterizing the low $$p_T$$ regions for the spectra, respectively. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.

Journal Articles

Local structure of Li-substituted (Bi$$_{0.5}$$Na$$_{0.5}$$)TiO$$_3$$

Yoneda, Yasuhiro; Hiruma, Yuji*; Nagata, Hajime*; Takenaka, Tadashi*

Japanese Journal of Applied Physics, 49(9), p.09ME09_1 - 09ME09_4, 2010/10

 Times Cited Count:12 Percentile:45.72(Physics, Applied)

(Ba$$_{0.5}$$Na$$_{0.5}$$)TiO$$_3$$ was carried out by a synchrotron radiation X-ray pair-distribution function (PDF) method. The PDF peak is resolved as a doublet owing to the presence of two phases with distinct local structures, those are rhombohedral and tetragonal phases. The dominant rhombohedral phase is stabilized by the Li substitution. The depolarization temperature ($$T_d$$) is increased as increasing the rhombohedral component in the local structure.

Journal Articles

Development of a TES microcalorimeter for spectroscopic measurement of LX-rays emitted by transuranium elements

Maehata, Keisuke*; Nakamura, Keisuke*; Yasumune, Takashi*; Ishibashi, Kenji*; Takasaki, Koji; Tanaka, Keiichi*; Odawara, Akikazu*; Nagata, Atsushi*

Journal of Nuclear Science and Technology, 47(3), p.308 - 313, 2010/03

 Times Cited Count:5 Percentile:35.66(Nuclear Science & Technology)

A phase transition edge sensor (TES) microcalorimeter was developed for the energy dispersive measurement of LX-ray photons emitted from transuranium elements. The phase transition temperature of the TES was designed to be 200 mK by using bilayer structure of Au of 120 nm thick and Ti of 50 nm thick. The Au layer of 5.0 $$mu$$m thick was deposited on the Au/Ti bilayer for absorption efficiency of 50% and counting rate of 100 counts per second in the detection of LX-ray photons with the energy from 10 to 20 keV. The TES microcalorimeter was operated for the detection of LX-ray photons emitted from $$^{241}$$Am, $$^{238}$$Pu and $$^{239}$$Pu sources. The decay time constant of 180 $$mu$$s of detection signal pulses allowed the TES microcalorimeter operating with the counting rate higher than 100 counts per second. The energy resolution was obtained to be 50 eV of FWHM value for a peak corresponding to $$^{237}$$Np L$$beta$$$$_{1}$$ X-ray of 17.75 keV.

Journal Articles

Shaking table tests with large test specimens of seismically isolated FBR plants, 3; Ultimate behavior of upper structure and rubber bearings

Yabana, Shuichi*; Kanazawa, Kenji*; Nagata, Seiji*; Kitamura, Seiji; Sano, Takeshi*

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07

Journal Articles

Effect of 14-MeV neutrons on strontium-aluminate-based long-lasting phosphor

To, Kentaro; Shikama, Tatsuo*; Katsui, Hirokazu*; Nagata, Shinji*; Tsuchiya, Bun*; Yamauchi, Michinori*; Nishitani, Takeo

Journal of Nuclear Materials, 386-388, p.1027 - 1029, 2009/04

 Times Cited Count:4 Percentile:30.43(Materials Science, Multidisciplinary)

Fluorescence and long-lasting emission properties of two types of Long-lasting phosphors (LLPs), SrAl$$_{2}$$O$$_{4}$$:Eu$$^{2+}$$,Dy$$^{3+}$$ and Sr$$_{4}$$Al$$_{14}$$O$$_{25}$$:Eu$$^{2+}$$,Dy$$^{3+}$$, were examined under 14-MeV neutron irradiation. The fluorescent spectra of the LLPs have characteristic peaks due to their dopants and the fluorescent intensity of Sr$$_{4}$$Al$$_{14}$$O$$_{25}$$:Eu$$^{2+}$$,Dy$$^{3+}$$ shows good radiation resistance for the neutrons fluence up to 10$$^{19}$$ n/m$$^{2}$$. Long-lasting emissions are exhibited after neutron irradiation, and the emission spectra have one peak due to Eu$$^{2+}$$. Further, it is found that there is an optimum neutron fluence at which the longest decay time is obtained.

Journal Articles

Damage process and luminescent characteristics in silica glasses under ion irradiation

Nagata, Shinji*; Katsui, Hirokazu*; Tsuchiya, Bun*; Inoue, Aichi; Yamamoto, Shunya; To, Kentaro; Shikama, Tatsuo*

Journal of Nuclear Materials, 386-388, p.1045 - 1048, 2009/04

 Times Cited Count:14 Percentile:66.87(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Isotope effects in thermal neutron transmission and backscattering processes for $$varepsilon$$-phase zirconium hydrides and deuterides

Tsuchiya, Bun*; Yasuda, Ryo; Teshigawara, Makoto; Konashi, Kenji*; Nagata, Shinji*; Shikama, Tatsuo*; Yamawaki, Michio*

Journal of Nuclear Materials, 376(1), p.60 - 65, 2008/05

 Times Cited Count:2 Percentile:16.95(Materials Science, Multidisciplinary)

Distributions of hydrogen isotope concentrations in e-phase zirconium hydrides and deuterides ($$varepsilon$$-ZrHx and $$varepsilon$$-ZrDx: 1.8 $$<$$ x $$<$$ 2.0) were investigated by neutron radiography (NRG). The NRG images of the thermal neutron transmission and backscattering revealed hydrogen concentration dependence and isotope differences. The thermal neutron mass attenuation coefficients in relation to the hydrogen isotope concentrations were determined from the transmission NRG images. The results showed the isotope effects of the thermal neutron mass attenuation coefficients for $$varepsilon$$-ZrHx to be about 6-9 times higher than those for $$varepsilon$$-ZrDx. The neutron scattering processes for transmission and backscattering NRG images of $$varepsilon$$-ZrHx and $$varepsilon$$-ZrDx were also analyzed using a general Monte Carlo neutron-particle transport (MCNP) code.

64 (Records 1-20 displayed on this page)