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Journal Articles

Short- and middle-ranges order structures of KNbO$$_3$$ nanocrystals

Yoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Fujii, Ichiro*; Nagata, Hajime*; Ohara, Koji*; Wada, Satoshi*

Japanese Journal of Applied Physics, 58(SL), p.SLLA03_1 - SLLA03_7, 2019/11

 Times Cited Count:0 Percentile:100(Physics, Applied)

Journal Articles

Local structure analysis of KNbO$$_3$$ nanocrystals with cubic shape

Yoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Ohara, Koji*; Wada, Satoshi*

Transactions of the Materials Research Society of Japan, 43(2), p.93 - 96, 2018/04

KNbO$$_3$$ nanocrystals were grown by solvothermal technique assisted by a microwave treatment. We performed high-energy X-ray diffraction to extract average and local structural parameters. The particle size can be evaluated by the Scherrer's equation. The unit cell size was reduced as the particle size increased. The local structure was found to be a rhombohedral structure, which was similar to that of the bulk KNbO$$_3$$.

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:2 Percentile:12.39

Journal Articles

Hydrogen absorption behavior on zirconium under $$gamma$$-radiolysis of nitric acid solution

Ishijima, Yasuhiro; Ueno, Fumiyoshi; Abe, Hitoshi

Nippon Genshiryoku Gakkai Wabun Rombunshi, 16(2), p.100 - 106, 2017/05

Zirconium (Zr) has been used as a structural material at the spent nuclear fuel reprocessing plant in Japan because of its excellent corrosion resistance against nitric acid solution. And the radiolytic hydrogen is known to be generated in the spent nuclear fuel solution. Zr is known to be highly susceptible to hydrogen embrittlement. Therefore, evaluating the radiolytic hydrogen absorption behavior of Zr in nitric acid solution (HNO$$_{3}$$) is essential. In this study, immersion tests were conducted on Zr in nitric acid solutions under $$gamma$$-ray irradiation to evaluate its radiolytic hydrogen absorption behavior. Results showed that hydrogen concentration on Zr increased both in 1-3 mol/L HNO$$_{3}$$ and pure water at 5 and 7 kGy/h after immersion. The amount of hydrogen absorption on Zr under $$gamma$$-ray irradiation had a direct correlation with the radiolytic hydrogen generation value in HNO$$_{3}$$. The results of glow discharge optical emission spectrometry, thermal desorption spectroscopy, and X-ray diffraction result shows that the absorbed radiolytic hydrogen generated a hydride on the surface of Zr.

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:5 Percentile:6.11

Journal Articles

The Effect of crystal textures on the anodic oxidization of zirconium in a boiling nitric acid solution

Kato, Chiaki; Ishijima, Yasuhiro; Ueno, Fumiyoshi; Yamamoto, Masahiro

Journal of Nuclear Science and Technology, 53(9), p.1371 - 1379, 2016/09

AA2015-0626.pdf:1.2MB

 Times Cited Count:2 Percentile:67.65(Nuclear Science & Technology)

The effects of crystal textures and the potentials in the anodic oxidation of zirconium in a boiling nitric acid solution were investigated to study the stress corrosion cracking of zirconium in nitric acid solutions. The growth of the zirconium oxide film dramatically changed depending on the applied potential at a closed depassivation potential (1.47 V vs. SSE). At 1.5 V, the zirconium oxide film rapidly grows, and its growth exhibits cyclic oxidation kinetics in accordance with a nearly cubic rate law. The zirconium oxide film grows according to the quantity of electric charge, and the growth rate does not depend on the crystal texture in the pretransition region before the cyclic oxidation kinetics. However, the growth and cracking under the thick oxide film depend on the crystal texture in the transition region. On the normal direction side, the oxide film thickness decreases on average since some areas of the thick oxide film are separated from the specimen surface owing to the cracks in the thick oxide. On the rolling direction side, cracks are found under the thick oxide film, which deeply propagate along the RD without an external stress. The cracks under the thick oxide film propagate to the center of the oxide layer. The cracks in the oxide layer propagate in the (0002)Zr plane in the zirconium matrix. The oxide layer consists of string-like zirconium oxide and zirconium hydride. The string-like zirconium oxide contains orthorhombic ZrO$$_{2}$$ in addition to monoclinic ZrO$$_{2}$$. As one assumption for the mechanism of crack initiation and propagation without an external stress, it is considered that the oxidizing zirconium hydrides precipitate in the (0002)Zr and then the phase transformation from orthorhombic ZrO$$_{2}$$ to monoclinic ZrO$$_{2}$$ in the oxide layer causes the crack propagation in the (0002) plane.

Journal Articles

Thermal aging effect for creep properties on Ni base refractory alloys

Ishijima, Yasuhiro; Ueno, Fumiyoshi

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05

In this study, to evaluate the effect of thermal aging on creep properties of Alloy 625, we carried out creep tests on aged and solution-treated Alloy 625 at 1073 K. According to the creep test results, time-to-rupture decreased by thermal aging when test stress was more than 100 MPa, but did not change when test stress was less than 100 MPa for any specimens. In the solution-treated alloy, creep deformation behaviors changed over 100 MPa. These results show that time-to-rupture was constant because intermetallic compounds precipitated when the test stress was less than 100 MPa in solution-treated alloy. The observed relationship between creep strain rate and test time showed that the precipitation started after 100 hr for solution treated alloys. These results suggest that intermetallic compounds precipitate immediately after furnace operation. And it is appropriate to use creep data of thermal-aged Alloy 625 for the reducing roasting furnace lifetime prediction.

Journal Articles

Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.

Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12

 Times Cited Count:5 Percentile:53.8(Physics, Nuclear)

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Journal Articles

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

no abstracts in English

Journal Articles

Progress of injection energy upgrade project for J-PARC RCS

Hayashi, Naoki; Harada, Hiroyuki; Horino, Koki; Hotchi, Hideaki; Kamiya, Junichiro; Kinsho, Michikazu; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; et al.

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3833 - 3835, 2014/07

no abstracts in English

Journal Articles

Power supply of the pulse steering magnet for changing the painting area between the MLF and the MR at J-PARC 3 GeV RCS

Takayanagi, Tomohiro; Hayashi, Naoki; Ueno, Tomoaki; Horino, Koki; Togashi, Tomohito; Kinsho, Michikazu; Watanabe, Yasuhiro; Irie, Yoshiro*

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.681 - 683, 2014/07

The power supply of the pulse steering magnet has been produced. The power supply has the equipment used to excite the pulse current and the direct-current (DC) to correspond to two modes that the painting injection for beam users and the central injection for beam commissioning. The pulse current has been performed with good accuracy whose deviation to a setting current becomes to be less than 0.2%. In case of the central injection, the power supply excites the current in DC mode, which has been realized the ripple current below 0.01%. This paper describes the design parameters and the experimental results of the power supply.

Journal Articles

Reduction mechanism of nitate on titanium

Komatsu, Atsushi; Ishijima, Yasuhiro; Motooka, Takafumi; Ueno, Fumiyoshi; Yamamoto, Masahiro

Zairyo To Kankyo, 62(5), p.198 - 203, 2013/05

Reduction mechanism of nitrate ion on titanium electrode was investigated using electrochemical method. Cathodic polarization curve of titanium was measured in nitric acid with different concentrations of ions (H$$^{+}$$,NO$$_{3}$$$$^{-}$$,HNO$$_{2}$$). Reduction mechanism of nitrate ion on titanium was investigated from Tafel slope and reaction order of each ions. It was considered that reduction of titanium oxide was involved in reduction mechanism of nitrate ion on titanium, and reduction mechanism was suggested as follows. NO$$_3^{-}$$ $$rightleftharpoons$$ NO$$_{3ad}^{-}$$ (QE), TiO$$_{2}$$ + H$$^{+}$$ + e$$^{-}$$ $$rightleftharpoons$$ TiOOH (QE), NO$$_{3ad}^{-}$$ + TiOOH $$rightarrow$$ (NO$$_3^{-}$$ - TiOOH)$$_{ad}$$ (RDS), (NO$$_3^{-}$$ - TiOOH)$$_{ad}$$ + H$$^{+}$$ + e$$^{-}$$ $$rightarrow$$ NO$$_{2ad}^{-}$$ + TiO$$_{2}$$ + H$$_{2}$$O

Journal Articles

Sagittal focusing of synchrotron radiation X-rays using a winged crystal

Nisawa, Atsushi*; Yoneda, Yasuhiro; Ueno, Go*; Murakami, Hironori*; Okajima, Yuka*; Yamamoto, Kenichiro*; Semba, Yasunori*; Uesugi, Kentaro*; Tanaka, Yoshihito*; Yamamoto, Masaki*; et al.

Journal of Synchrotron Radiation, 20(2), p.219 - 225, 2013/03

 Times Cited Count:10 Percentile:42.4(Instruments & Instrumentation)

A Si(111) winged crystal has been designed to minimize anticlastic bending and improve sagittal focusing efficiency. The crystal was thin with wide stiffening wings. The length-to-width ratio of the crystal was optimized by finite element analysis, and the optimal value was larger than the "golden value". The analysis showed that the slope error owing to anticlastic bending is less than the Darwin width. The X-rays were focused two-dimensionally using the crystal and a tangentially bent mirror. The observed profiles of the focal spot agreed well with the results of a ray-tracing calculation in the energy range from 8 to 17.5 keV. X-ray diffraction measurements with a high signal-to-noise ratio using this focusing system were demonstrated for a small protein crystal.

Journal Articles

Operation maintenance of the thyratron for the power supply of the extraction kicker magnet in the J-PARC 3GeV RCS

Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro; Kinsho, Michikazu

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.471 - 473, 2012/08

The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) uses 8 pulse kicker magnets for the beam extraction at a repetition rate of 25 Hz. Each kicker power supply has 2 thyratrons and thus they are 16 in total. An average life time of thyratrons even more than the J-PARC annual operation time of 5000 hours and a stable operation with a downtime of less than only 0.5% has already been achieved. The present maintenance procedures and statistics for the long term operation with thyratrons are reported in this paper.

Journal Articles

Current status of the kicker thyratron operation in J-PARC 3GeV RCS

Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.579 - 583, 2010/08

The 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) has the pulse kicker power supply system which uses the thyratron switches for beam extraction. There were many troubles caused by unstable operation of thyratrons after beam commissioning started in January 2009. The, failure rate of the kicker power supply system was about 13%. To improve this status, we have been managed the operations of the thyratron in detail. As a result, the unstable operation has been improved and the failure rate has been achievement less than 0.5% (Run33) in April, 2010. In this paper, we report current status of the thyratron operation of the kicker power supply system.

Journal Articles

Operation of kicker system using thyratron of the 3 GeV rapid cycling synchrotron of J-PARC

Watanabe, Masao; Kamiya, Junichiro; Suganuma, Kazuaki; Takayanagi, Tomohiro; Tani, Norio; Togashi, Tomohito; Ueno, Tomoaki; Watanabe, Yasuhiro

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3296 - 3298, 2010/05

3 GeV rapid cycling synchrotron of J-PARC accelerates proton beams from the 181 MeV up to 3 GeV. Proton beams in the RCS are fast extracted by kicker magnets at the repetition rate of 25 Hz. The rise time of the magnetic field is approximately 260 ns due to the propagation time through the coaxial cable and the kicker magnet itself. The flat top length of it is required to 840 ns in order to extract two beam bunches. Pulse forming lines (PFL) and thyratrons are used to make the rise time and the flat top, at the maximum charging voltage of 80 kV. 16 thyratrons are used in the eight power supplies of the kicker system. Since thyratrons are gaseous discharge switching devices, they often make misfire or self-breakdown in several hours. In this paper, present status of operation and voltage adjustment method of the reservoir and cathode heater power supply of the thyratrons in the kicker system are described.

Journal Articles

Transverse beam matching and orbit corrections at J-PARC LINAC

Sako, Hiroyuki; Ueno, Akira; Okawa, Tomohiro*; Kondo, Yasuhiro; Morishita, Takatoshi; Ikegami, Masanori*; Akikawa, Hisashi*

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.260 - 262, 2009/00

In designed very high intensity proton beam of J-PARC LINAC, precise control of transverse beam dynamics is extremely important for suppression of beam loss. We present results of transverse beam matching and orbit corrections. Excellent matching performance has been achieved with mismatch factor less than 5% at beam current of 5 to 30 mA. Orbit deviations were suppressed within 1mm in horizontal and vertical directions in the whole LINAC.

Journal Articles

Operating experience of the J-PARC linac

Hasegawa, Kazuo; Asano, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; Ito, Takashi; Kobayashi, Tetsuya; Kondo, Yasuhiro; Namekawa, Yuya; Oguri, Hidetomo; Okoshi, Kiyonori; et al.

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.55 - 57, 2009/00

The beam commissioning of the J-PARC linac started in November 2006 and 181 MeV acceleration was successfully achieved in January 2007. The linac has delivered beams to the 3 GeV Rapid Cycling Synchrotron for its commissioning, and then, the subsequent Main Ring Synchrotron and the neutron target commissioning. The linac uses a Cs-free LaB$$_{6}$$-driven ion source and 20 units of 324 MHz klystrons. As of June 2008, the operation times are about 3,000 and 6,000 hours for the ion source and the RF source, respectively. The operating experience of the linac is described.

Journal Articles

Development and operation of a Cs-free J-PARC H$$^{-}$$ ion source

Oguri, Hidetomo; Ueno, Akira; Namekawa, Yuya; Okoshi, Kiyonori; Kondo, Yasuhiro; Ikegami, Kiyoshi*

Review of Scientific Instruments, 79(2), p.02A506_1 - 02A506_4, 2008/02

 Times Cited Count:8 Percentile:56.85(Instruments & Instrumentation)

A cesium-free negative hydrogen ion source driven with a LaB6 filament was developed for the J-PARC (Japan Proton Accelerator Research Complex). It is being operated for the J-PARC LINAC beam commissioning, which was started on 20 November 2006. Nine runs of 2-week beam commissioning will be done until the end of June 2007. The source is operated with a duty factor of 0.8 % (0.32 ms and 25 Hz) while providing a 5 mA beam typically. Each interval of the runs, optimizations, such as the filament position and so on, are examined. At present, a 39 mA beam is successfully extracted with a duty factor of 0.8 %.

Journal Articles

Beam energy measurement at J-PARC linac

Sato, Susumu; Igarashi, Zenei*; Tomisawa, Tetsuo; Miura, Akihiko; Ueno, Akira; Sako, Hiroyuki; Morishita, Takatoshi; Kondo, Yasuhiro; Shen, G.; Akikawa, Hisashi*; et al.

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.500 - 502, 2008/00

no abstracts in English

64 (Records 1-20 displayed on this page)