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Journal Articles

Melting of Pb charge glass and simultaneous Pb-Cr charge transfer in PbCrO$$_{3}$$ as the origin of volume collapse

Yu, R.*; Hojo, Hajime*; Watanuki, Tetsu; Mizumaki, Masaichiro*; Mizokawa, Takashi*; Oka, Kengo*; Kim, H.*; Machida, Akihiko; Sakaki, Koji*; Nakamura, Yumiko*; et al.

Journal of the American Chemical Society, 137(39), p.12719 - 12728, 2015/10

 Times Cited Count:23 Percentile:65.97(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Development status of pulse duty management system for injector commissioning of IFMIF/EVEDA accelerator

Takahashi, Hiroki; Narita, Takahiro; Usami, Hiroki; Sakaki, Hironao; Kojima, Toshiyuki*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.756 - 759, 2015/09

no abstracts in English

Journal Articles

Observation of transient structural changes on hydrogen absorption process of LaNi$$_{4.75}$$Sn$$_{0.25}$$ by time resolved X-ray diffraction

Machida, Akihiko; Higuchi, Kensuke*; Katayama, Yoshinori; Sakaki, Koji*; Kim, H.*; Nakamura, Yumiko*

Nihon Kinzoku Gakkai-Shi, 79(3), p.124 - 130, 2015/03

 Times Cited Count:4 Percentile:28.87(Metallurgy & Metallurgical Engineering)

Structural changes on hydrogen absorption process of hydrogen absorbing alloy LaNi$$_{4.75}$$Sn$$_{0.25}$$ have been investigated by time-resolved X-ray diffraction measurements using synchrotron radiation source. We have found the transient intermediate phase between the solid solution and hydride phases of LaNi$$_{4.75}$$Sn$$_{0.25}$$ under non-equilibrium hydrogen pressure condition at room temperature. LaNi$$_{4.75}$$Sn$$_{0.25}$$ has transformed into the hydride through three phase co-existing state. The hydrogen content of the intermediate phase estimated from the unit cell volume is independent of the induced hydrogen gas pressure. The variation of lattice constants indicate that the hydrogen atoms are located at the La$$_{2}$$Ni$$_{2}$$(Ni,Sn)$$_{2}$$ octahedron and La$$_{2}$$(Ni,Sn)$$_{2}$$ tetrahedron in the intermediate phase.

Journal Articles

Compositional dependence of hydrogenation properties in Ti$$_{1+y}$$(Fe$$_{1-x}$$Mn$$_{x}$$)$$_{1-y}$$ ($$0.2 leq x leq 0.5$$, $$0 leq y leq 0.08$$)

Sakaki, Koji*; Kim, H.*; Machida, Akihiko; Watanuki, Tetsu; Nakamura, Yumiko*

Nihon Kinzoku Gakkai-Shi, 79(3), p.112 - 117, 2015/03

 Times Cited Count:2 Percentile:8.58(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Effect of a quenching rate on hydrogen storage properties of V$$_{0.79}$$Ti$$_{0.2}$$Zr$$_{0.01}$$

Kim, H.*; Sakaki, Koji*; Asano, Kota*; Ikeda, Kazutaka*; Otomo, Toshiya*; Machida, Akihiko; Watanuki, Tetsu; Nakamura, Yumiko*

Nihon Kinzoku Gakkai-Shi, 79(3), p.131 - 136, 2015/03

 Times Cited Count:0 Percentile:0.01(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Improvement of hydrogen storage properties of Mg$$_{1-x}$$Pr$$_{x}$$Ni$$_{4}$$ by Changing Mg/Pr ratio

Sakaki, Koji*; Terashita, Naoyoshi*; Kim, H.*; Majzoub, E. H.*; Proffen, T.*; Machida, Akihiko; Watanuki, Tetsu; Tsunokake, Shigeru*; Nakamura, Yumiko*; Akiba, Etsuo*

Sumato Purosesu Gakkai-Shi, 3(6), p.359 - 366, 2014/11

no abstracts in English

Journal Articles

Safety managements of the linear IFMIF/EVEDA prototype accelerator

Takahashi, Hiroki; Maebara, Sunao; Kojima, Toshiyuki; Narita, Takahiro; Tsutsumi, Kazuyoshi; Sakaki, Hironao; Suzuki, Hiromitsu; Sugimoto, Masayoshi

Fusion Engineering and Design, 89(9-10), p.2066 - 2070, 2014/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Development status of control system for IFMIF/EVEDA prototype accelerator

Takahashi, Hiroki; Narita, Takahiro; Nishiyama, Koichi; Usami, Hiroki; Sakaki, Hironao; Kasugai, Atsushi; Kojima, Toshiyuki*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.799 - 802, 2014/10

no abstracts in English

Journal Articles

Reduction and unusual recovery in the reversible hydrogen storage capacity of V$$_{1-x}$$Ti$$_x$$ during hydrogen cycling

Kim, H.*; Sakaki, Koji*; Saita, Itoko*; Enoki, Hirotoshi*; Noguchi, Kazuo*; Machida, Akihiko; Watanuki, Tetsu; Nakamura, Yumiko*

International Journal of Hydrogen Energy, 39(20), p.10546 - 10551, 2014/07

 Times Cited Count:10 Percentile:30.26(Chemistry, Physical)

The effect of the vanadium content on the cyclic stability of V-Ti binary alloys was investigated. V$$_{1-x}$$Ti$$_x$$, $$x=$$ 0.2 and 0.5 samples were hydrogenated and dehydrogenated at 410 K and 553 K respectively, for more than 100 times. During hydrogen cycling, reduction in the reversible hydrogen storage capacity was clearly observed from both samples. In addition, the shape of the pressure-composition-isotherm curves was significantly altered over the testing cycle period; the absorption and desorption plateaus got markedly inclined and the hysteresis became evidently smaller. We found that even after the hydrogen storage capacity of V$$_{1-x}$$Ti$$_x$$ was significantly reduced, at low enough temperature V$$_{1-x}$$Ti$$_x$$ was able to absorb hydrogen as much as it did at the first cycle.

Journal Articles

Interface test between IFMIF/EVEDA accelerator control system and injector

Takahashi, Hiroki; Kojima, Toshiyuki; Narita, Takahiro; Maebara, Sunao; Sakaki, Hironao; Suzuki, Hiromitsu

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.724 - 727, 2014/06

no abstracts in English

Journal Articles

Degradation mechanism against hydrogenation cycles in Mg$$_{2-x}$$Pr$$_x$$Ni$$_4$$ ($$x$$ = 0.6 and 1.0)

Sakaki, Koji*; Terashita, Naoyoshi*; Kim, H.*; Majzoub, E. H.*; Machida, Akihiko; Watanuki, Tetsu; Tsunokake, Shigeru*; Nakamura, Yumiko*; Akiba, Etsuo*

Journal of Physical Chemistry C, 118(13), p.6697 - 6705, 2014/04

 Times Cited Count:13 Percentile:44.39(Chemistry, Physical)

We present an investigation of the degradation mechanism against hydrogenation cycles in Mg$$_{2-x}$$Pr$$_x$$Ni$$_4$$ ($$x$$ = 0.6 and 1.0). Mg$$_{1.0}$$Pr$$_{1.0}$$Ni$$_{4}$$ shows significant degradation and loss of capacity after only a few cycles, while Mg$$_{1.4}$$Pr$$_{0.6}$$Ni$$_{4}$$ did not show any reduction of hydrogen storage capacity until 100 cycles. The peak broadening of X-ray diffraction patterns and accumulation of lattice strain were observed concomitantly with an increase of hydrogenation cycles only in Mg$$_{1.0}$$Pr$$_{1.0}$$Ni$$_{4}$$. These changes were not observed in Mg$$_{1.4}$$Pr$$_{0.6}$$Ni$$_{4}$$. In pair distribution function patterns, $$r$$-dependent peak broadening was observed and it became significant with an increasing number of cycles in Mg$$_{1.0}$$Pr$$_{1.0}$$Ni$$_{4}$$, suggesting an increase of the dislocation density. Mg$$_{1.4}$$Pr$$_{0.6}$$Ni$$_{4}$$ showed higher hardness and more pulverization upon hydrogenation than Mg$$_{1.0}$$Pr$$_{1.0}$$Ni$$_{4}$$.

Journal Articles

Evaluation of dose level in a laser-driven ion accelerator using PHITS code

Sakaki, Hironao; Fukuda, Yuji; Nishiuchi, Mamiko; Jinno, Satoshi; Kanasaki, Masato; Yogo, Akifumi; Kondo, Kiminori; Saito, Fumihiro; Fukami, Tomoyo; Ueno, Masayuki; et al.

Progress in Nuclear Science and Technology (Internet), 4, p.182 - 185, 2014/04

The concept of a compact ion particle accelerator has become attractive in view of recent progress in laser-driven ions acceleration. In the development of many applications of laser-accelerated ions, it is necessary for securing the radiation safety to calculate the dose evaluation. The dose was measured with the radio-photoluminescent (RPL) glass dosimeter on the test beamline of at laser-driven accelerator. The Monte Carlo code, PHITS (Particle and Heavy Ion Transport code system) simulation is shown to be reasonably predictive at the test beamline for measured with the RPL glass dosimeter. We compare of the measured dose level on the laser-driven accelerator with the result of PHITS code in this report.

Journal Articles

Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration

Sakaki, Hironao; Nishiuchi, Mamiko; Maeda, Shota; Sagisaka, Akito; Pirozhkov, A. S.; Pikuz, T.; Faenov, A.*; Ogura, Koichi; Fukami, Tomoyo; Matsukawa, Kenya*; et al.

Review of Scientific Instruments, 85(2), p.02A705_1 - 02A705_4, 2014/02

 Times Cited Count:2 Percentile:13.22(Instruments & Instrumentation)

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams. Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity os 1$$times$$10$$^{21}$$ W/cm$$^{2}$$ on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System (PHITS). The results obtained provide useful approach for analyzing the various laser based ion beams.

Journal Articles

In situ synchrotron $$^{57}$$Fe M$"o$ssbauer spectroscopy of RFe$$_{2}$$ (R = Y, Gd) hydrides synthesized under ultra-high-pressure hydrogen

Mitsui, Takaya; Masuda, Ryo*; Seto, Makoto; Hirao, Naohisa*; Matsuoka, Takehiro*; Nakamura, Yumiko*; Sakaki, Koji*; Enoki, Hirotoshi*

Journal of Alloys and Compounds, 580(Suppl.1), p.S264 - S267, 2013/12

 Times Cited Count:4 Percentile:31.72(Chemistry, Physical)

Journal Articles

Origin of degradation in the reversible hydrogen storage capacity of V$$_{1-x}$$Ti$$_{x}$$ alloys from the atomic pair distribution function analysis

Kim, H.*; Sakaki, Koji*; Ogawa, Hiroshi*; Nakamura, Yumiko*; Nakamura, Jin*; Akiba, Etsuo*; Machida, Akihiko; Watanuki, Tetsu; Proffen, T.*

Journal of Physical Chemistry C, 117(50), p.26543 - 26550, 2013/12

 Times Cited Count:30 Percentile:72.62(Chemistry, Physical)

Reduction in reversible hydrogen storage capacity with increasing hydrogenation and dehydrogenation cycle number is observed in numerous hydrogen storage materials, but the mechanism behind this unfavorable change has not been elucidated yet. In this study, we have investigated the development of structural defects or disorders in V$$_{1-x}$$Ti$$_x$$H$$_2$$, $$x$$ = 0, 0.2, and 0.5, during the first 15 hydrogen absorption and desorption cycles using the atomic pair distribution function (PDF) analysis of synchrotron X-ray total scattering data to find out the possible structural origin of the poor cyclic stability of V$$_{1-x}$$Ti$$_x$$ alloys.

Journal Articles

$$gamma$$-ray and neutron area monitoring system of linear IFMIF prototype accelerator building

Takahashi, Hiroki; Kojima, Toshiyuki; Narita, Takahiro; Tsutsumi, Kazuyoshi; Maebara, Sunao; Sakaki, Hironao; Nishiyama, Koichi

Fusion Engineering and Design, 88(9-10), p.2736 - 2739, 2013/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

For radiation safety of the Linear IFMIF Prototype Accelerator, $$gamma$$-ray and neutron area monitoring system are designed. This system monitors and records the measured data by using both a supervisory board in the access room and central control system. The interlock signals are sent to Personnel Protection System (PPS) and Machine Protection System (MPS) when the integrated dose value exceeds a threshold value. After receiving them, the PPS and the MPS immediately inhibit the beam operation for secure radiation safety. This monitoring system is designed to achieve a high reliability for data transfer using hardwired interlock signals and the performance of data communication between area monitoring system and control system.

Journal Articles

Development of a single-shot-imaging thin film for an online Thomson parabola spectrometer

Sakaki, Hironao; Kanasaki, Masato; Fukuda, Yuji; Nishiuchi, Mamiko; Hori, Toshihiko; Yogo, Akifumi; Jinno, Satoshi; Niita, Koji*

Review of Scientific Instruments, 84(1), p.013301_1 - 013301_7, 2013/01

 Times Cited Count:5 Percentile:30.23(Instruments & Instrumentation)

A single-shot-imaging thin scintillator film was developed for an online Thomson parabola (TP) spectrometer and the first analysis of laser accelerated ions, using the online TP spectrometer, was demonstrated at the JAEA-Kansai Advanced Relativistic Engineering Laser System (J-KAREN). An energy spectrum of 4.0 MeV protons is obtained using only this imaging film without the need of a microchannel plate that is typically utilized in online ion analyses. A general-purpose Monte Carlo particle and heavy ion-transport code system, which consists of various quantum dynamics models, was used for the prediction of the luminescent properties of the scintillator. The simulation can reasonably predict not only the ion trajectories detected by the spectrometer, but also luminescence properties.

Journal Articles

Development status of data acquisition system for LIPAc

Takahashi, Hiroki; Kojima, Toshiyuki; Narita, Takahiro; Sakaki, Hironao; Komukai, Satoshi*

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3972 - 3974, 2012/07

Control System for LIPAc realizes the remote control and monitoring and data acquisition by use of EPICS. For the validations of each subsystem performance and the activity of IFMIF Accelerator design, it is very important data obtained by commissioning of LIPAc and each subsystem. To certainly archive the important data for LIPAc and to efficiently search the LIPAc data, for design and validation, we started developing Data Acquisition System (DAC) based on Relational Database (RDB) has been developed. The first design for DAC of LIPAc is configured (1) using PostgreSQL for RDB and (2) several RDB for data archiving to ensure the data archive performance and to consider the increasing data amount. In addition, (3) only one RDB for data search is included in DAC and users can search the data via this RDB. In this way, several RDB for DAC can behave only one RDB against users. In this article, the development status of DAC for LIPAc is presented.

Journal Articles

An in situ M$"{o}$ssbauer study using synchrotron radiation

Masuda, Ryo; Mitsui, Takaya; Ito, Keiji*; Sakaki, Koji*; Enoki, Hirotoshi*; Nakamura, Yumiko*; Seto, Makoto

Hyperfine Interactions, 204(1-3), p.139 - 142, 2012/03

 Times Cited Count:2 Percentile:79.02

We have been developing a system for in situ M$"{o}$ssbauer studies using synchrotron radiation (SR) to elucidate the mechanism of hydrogenation processes. In the system, samples reacts in an atmosphere chamber and SR-based M$"{o}$ssbauer spectra using variable-frequency nuclear monochromator and energy spectra of inelastic nuclear resonant scattering (NRS) of SR are measured. As a feasibility study, the temperature dependence of the M$"{o}$ssbauer and inelastic NRS spectra of $$^{57}$$Fe in $$c$$-GdFe$$_2$$H$$_3$$ under vacuum were measured. In both spectra, clear differences were observed between 373 K and 573 K. These differences can be interpreted by the change of microscopic environment around Fe at the dehydrogenation. Thus, it is confirmed that this system works well enough to perform the in-situ M$"{o}$ssbauer study on the dehydrogenation of $$c$$-GdFe$$_2$$H$$_3$$.

Journal Articles

Design of $$gamma$$-ray and neutron area monitoring system for the IFMIF/EVEDA accelerator building

Takahashi, Hiroki; Maebara, Sunao; Kojima, Toshiyuki; Kubo, Takashi; Sakaki, Hironao; Takeuchi, Hiroshi; Shidara, Hiroyuki; Hirabayashi, Keiichi*; Hidaka, Kosuke*; Shigyo, Nobuhiro*; et al.

Fusion Engineering and Design, 86(9-11), p.2795 - 2798, 2011/10

 Times Cited Count:2 Percentile:20.43(Nuclear Science & Technology)

In the IFMIF/EVEDA accelerator, the engineering validation up to 9 MeV by employing the deuteron beam of 125 mA are planning at the BA site in Rokkasho, Aomori, Japan, the personnel protection system (PPS) is indispensable. The PPS inhibit the beam by receiving the interlock signal from the $$gamma$$-ray and neutron monitoring system. The $$gamma$$-ray and neutron detection level which is planned to be adopted are "80 keV to 1.5 MeV ($$gamma$$-ray)" and "0.025 eV to 15 MeV (neutron)". For the present shielding design, it is absolutely imperative for the safety review to validate the shielding ability which makes detection level lower than these $$gamma$$-ray and neutron detector. For this purpose, the energy reduction of neutron and photon for water and concrete is evaluated by PHITS code. From the calculating results, it is found that the photon energy range extended to 10 MeV by water and concrete shielding material only, an additional shielding to decrease the photon energy of less than 1.5 MeV is indispensable.

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