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Journal Articles

Internal residual stress evaluation of bearing balls for automobile parts

Miyakawa, Susumu*; Ito, Toshimasa*; Iwahori, Keisuke*; Aoyama, Yoshihiko*; Kubo, Ryosuke*; Murata, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Kajiwara, Kentaro*

Zairyo, 69(4), p.308 - 314, 2020/04

White etching area which looks white with nital corrosive liquid may be recognized at the flaking part of a rolling bearing on which high contact stress of several GPa is applied repeatedly. Up to now, studies of white etching area of a ball have been less than studies of white etching area of inner and outer rings. In this study, as part of the flaking mechanism explication with white etching area of a ball, internal residual stress distributions of ball by using high energy white X-ray of SPring-8 (A method) and laboratorial X-ray measurement equipment (B method) were investigated. The former was modified by surface residual stress according to B method. The latter was modified by releasing stress in the form of electrolytic polishing. The results showed modified residual stress distributions almost agree qualitatively.

Journal Articles

Cryogenic sample environments shared at the MLF, J-PARC

Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.

Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05

The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading $$^4$$He cryostat, a bottom-loading $$^3$$He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The $$^3$$He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of $$^3$$He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.

Journal Articles

Quantum paramagnet near spin-state transition

Tomiyasu, Keisuke*; Ito, Naoko*; Okazaki, Ryuji*; Takahashi, Yuki*; Onodera, Mitsugi*; Iwasa, Kazuaki*; Nojima, Tsutomu*; Aoyama, Takuya*; Ogushi, Kenya*; Ishikawa, Yoshihisa*; et al.

Advanced Quantum Technologies (Internet), 1(3), p.1800057_1 - 1800057_7, 2018/12

Spin-state transition, also known as spin crossover, plays a key role in diverse systems. In theory, the boundary range between the low- and high-spin states is expected to enrich the transition and give rise to unusual physical states. However, no compound that realizes a nearly degenerate critical range as the ground state without requiring special external conditions has yet been experimentally identified. This study reports that the Sc substitution in LaCoO3 destabilizes its nonmagnetic low-spin state and generates an anomalous paramagnetic state accompanied by the enhancement of transport gap and magneto-lattice-expansion as well as the contraction of Co-O distance with the increase of electron site transfer. These phenomena are not well described by the mixture of conventional low- and high-spin states, but by their quantum superposition occurring on the verge of a spin-state transition.

JAEA Reports

Research of the tasks on risk communication enforcement in fiscal year 2015 (Contract research)

Tanaka, Masaru*; Aoyama, Isao*; Ishizaka, Kaoru*; Ohata, Yuki*; Fukuike, Iori*; Kawase, Keiichi; Watanabe, Masanori; Tokizawa, Takayuki; Miyagawa, Hiroshi*; Ishimori, Yuu

JAEA-Research 2017-003, 65 Pages, 2017/06

JAEA-Research-2017-003.pdf:2.92MB

JAEA Ningyo-toge Environmental Engineering Center and Fukushima Environmental Safety Center have same challenges in risk communication. As reference, similar domestic cases were investigated by our two Centers, and requirements for building long-term relationship were clarified. As follows; (1) Develop new relationship with various stakeholders in the region. (2) Make better use of existing resources (personnel, land and facilities, etc.). (3) Make a concerted effort to create new values with local stakeholders. (4) Make an opportunity which local stakeholders confirm safety and build confidence to the project. These efforts will enhance the opportunities for operators and residents to learn about environment management and environmental protection.

Journal Articles

Correlative imaging of live biological cells with a soft X-ray microscope and a fluorescence microscope

Kado, Masataka; Kishimoto, Maki; Tamotsu, Satoshi*; Yasuda, Keiko*; Aoyama, Masato*; Tone, Shigenobu*; Shinohara, Kunio*

AIP Conference Proceedings 1696, p.020019_1 - 020019_4, 2016/01

 Times Cited Count:3 Percentile:85.61

Soft X-ray microscope is a very powerful tool to observe cellular organelles of living biological cells and many works have demonstrated imaging of inner structures of the cells. However the inner structures are very complicated and it is difficult to identify the organelles obtained with the soft X-ray microscopes. We have proposed a hybrid imaging method with a soft X-ray microscope and a fluorescence microscope that is to observe the same biological cells with the both microscopes at the same time. Using the information of the cellular organelles obtained with the fluorescence microscope, inner structures obtained with the soft X-ray microscope are accurately identified. We have observed living biological cells by the hybrid imaging method. Since the soft X-ray microscope has higher spatial resolution than that of the fluorescence microscope, fine structures of the cellular organelles in the living biological cells were discussed.

Journal Articles

Imaging of fine structures of cellular organelles in hydrated biological cells by a soft X-ray microscope combined with a fluorescence microscope

Kado, Masataka; Kishimoto, Maki; Tamotsu, Satoshi*; Yasuda, Keiko*; Aoyama, Masato*; Shinohara, Kunio*

Proceedings of SPIE, Vol.8849, p.88490C_1 - 88490C_7, 2013/09

 Times Cited Count:1 Percentile:55.89

We have proposed to use a fluorescence microscope to identify the cellular organelles in the images obtained with the soft X-ray microscope observing the same cells with both microscopes. The cells were stained with several fluorescent dyes such as Mito-tracker, Phalloidin, and DAPI and after taking many fluorescence images of cellular organelles the cells were exposed to the flash soft X-rays. The obtained soft X-ray images and fluorescence images of the cells were directly compared and each of the cellular organelles such as mitochondria, actin filaments, and chromosomes in the soft X-ray images was clearly identified. Since the soft X-ray microscope has higher spatial resolution than that of the fluorescence microscope, fine structures of the cellular organelles in the hydrated biological cells were observed for the first time.

Journal Articles

Thirty years experience at the experimental fast reactor Joyo; High quality core management and irradiation field characterization technique

Maeda, Shigetaka; Ito, Chikara; Aoyama, Takafumi; Maeda, Yukimoto; Chatani, Keiji

Transactions of the American Nuclear Society, 103(1), p.581 - 582, 2010/11

The experimental fast reactor Joyo of the Japan Atomic Energy Agency is the first liquid sodium fast reactor in Japan. Thirty years of successful operation of Joyo has shown excellent safety and reliability, and has contributed much to the LMFBR development program. Many kinds of irradiation experience have been accumulated to develop the fuels and materials for the prototype reactor Monju and future fast reactors. Accumulated data have been registered with OECD/NEA database with expectation that these data will be widely used. Joyo is presently temporary shutdown because of periodical inspection including in-vessel inspection and repair. After restart, Joyo will play a key role for a wide variety of science and technology fields as fast neutron irradiation bed.

Journal Articles

Controlling the phase matching conditions of optical parametric chirped-pulse amplification using partially deuterated KDP

Ogawa, Kanade; Sueda, Keiichi*; Akahane, Yutaka; Aoyama, Makoto; Tsuji, Koichi; Fujioka, Kana*; Kanabe, Tadashi*; Yamakawa, Koichi; Miyanaga, Noriaki*

Optics Express (Internet), 17(10), p.7744 - 7749, 2009/05

 Times Cited Count:13 Percentile:54.3(Optics)

Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.

Journal Articles

Development and characterization of a neutron personal dose equivalent monitor

Tsujimura, Norio; Yoshida, Tadayoshi; Nunomiya, Tomoya*; Aoyama, Kei*

Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM), 9 Pages, 2008/10

The authors developed a new neutron-measuring instrument that was designed to measure a neutron personal dose equivalent, H$$_{p}$$(10). This instrument is composed of a conventional moderator-based neutron dose equivalent meter and a neutron shield made of borated polyethylene which covers a backward hemisphere to adjust the angular dependence. The whole design was determined on the basis of MCNP calculations so as to have response characteristics which would generally match both energy and angular dependencies of H$$_{p}$$(10). The verification experiments for energy and angular responses were done using monoenergetic neutrons produced by the accelerator and polyenergetic neutrons from the moderated $$^{252}$$Cf source. As results of experiments, it is found that this new instrument has reasonably acceptable responses as a reference neutron dosemeter.

Journal Articles

Performance test of the electronic personal neutron dosemeter in neutron fields simulating workplaces of MOX fuel fabrication facilities

Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie; Nunomiya, Tomoya*; Aoyama, Kei*

Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM), 8 Pages, 2008/10

The authors assessed performance of electronic personal neutron dosemeters (EPD). The EPD selected in this study is NRY21, manufactured by Fuji Electric Systems Co., Ltd. This dosemeter uses two silicon semiconductor detectors to provide wide measurable energy ranges from thermal to several tens of MeV. In the test, we focused on the energy and angular dependences of dose equivalent responses because it was of great importance in neutron dosimetry in work environments. Measurements of dose equivalent responses were performed in the moderated neutron field reproducing neutron spectra likely to be encountered in workplaces of MOX fuel facilities. Neutron dose equivalents given by EPD were compared with reference dose values. As a result, dose equivalent responses of this EPD were evaluated to be 0.7 to 1.1 for normal incidence of neutron irradiation. This is satisfactory performance required for personal neutron monitoring.

Journal Articles

Celebration of 30th anniversary of the experimental fast reactor Joyo

Nakai, Satoru; Aoyama, Takafumi; Ito, Chikara; Yamamoto, Masaya; Iijima, Minoru; Nagaoki, Yoshihiro; Kobayashi, Atsuko; Onoda, Yuichi; Ohgama, Kazuya; Uwaba, Tomoyuki; et al.

Kosoku Jikkenro "Joyo" Rinkai 30-Shunen Kinen Hokokukai Oyobi Gijutsu Koenkai, 154 Pages, 2008/06

no abstracts in English

Journal Articles

Development of a neutron personal dose equivalent detector

Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie; Momose, Takumaro; Nunomiya, Tomoya*; Aoyama, Kei*

Radiation Protection Dosimetry, 126(1-4), p.261 - 264, 2007/08

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

The authors developed a new neutron measuring-instrument that was designed to measure neutron personal dose equivalent, $$H$$$$_{rm p}$$(10). This detector is composed a central thermal neutron detector, a core-polyethylene moderator, a front-hemispherical polyethylene moderator and rear-hemispherical boron-contained polyethylene absorber. Dimensions of each part were determined so as to provide energy- and angular-responses close to energy- and angular-dependencies of neutron $$H$$$$_{rm p}$$(10), based on the Monte Carlo calculations.

Journal Articles

Generation of broadband mid-infrared pulses by noncollinear difference frequency mixing

Sugita, Akihiro; Yokoyama, Keiichi; Yamada, Hidetaka; Inoue, Norihiro*; Aoyama, Makoto; Yamakawa, Koichi

Japanese Journal of Applied Physics, Part 1, 46(1), p.226 - 228, 2007/01

 Times Cited Count:7 Percentile:30.15(Physics, Applied)

Generation of broadband mid-infrared (MIR) laser pulses by difference frequency mixing (DFM) is reported. Two-color femtosecond pulses from a Ti: Sapphire laser system is mixed in an AgGaS$$_{2}$$ crystal utilizing a noncollinear phase matching scheme. The relative bandwidth of the generated MIR pulse has been measured to be 23 % to the central frequency, the broadest in DFM-based MIR sources reported so far. It is found that the type-I crystal can give broader phase matching range of spectrum than the type-II crystal within this scheme.

Journal Articles

Selective transition to the closely-lying states Cs(7$$D$$$$_{3/2}$$) and Cs(7$$D$$$$_{5/2}$$) by femtosecond laser pulses

Yamada, Hidetaka; Yokoyama, Keiichi; Teranishi, Yoshiaki*; Sugita, Akihiro; Shirai, Toshizo*; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.

Physical Review A, 72(6), p.063404_1 - 063404_5, 2005/12

 Times Cited Count:6 Percentile:31.26(Optics)

A demonstration of coherent quantum control for ultrafast precise selection of closely-lying states is reported. A phase-locked pair of femtosecond laser pulses is generated through a pulse shaper to excite the ground-state cesium atom to the Cs(7$$D$$$$_{3/2}$$) and Cs(7$$D$$$$_{5/2}$$) states by two-photon absorption. The excited state population is measured by detecting fluorescence from each spin-orbit state. By controlling the phase-difference of the pulse pair, an ultrafast precise selection is accomplished. The contrast ratio of the maximal to minimal selection ratio exceeds 10$$^3$$ with the delay less than 400 fs.

JAEA Reports

Study on the prediction accuracy of nuclide generation and depletion with JENDL

Okumura, Keisuke; Oki, Shigeo*; Yamamoto, Munenari*; Matsumoto, Hideki*; Ando, Yoshihira*; Tsujimoto, Kazufumi; Sasahara, Akihiro*; Katakura, Junichi; Matsumura, Tetsuo*; Aoyama, Takafumi*; et al.

JAERI-Research 2004-025, 154 Pages, 2005/01

JAERI-Research-2004-025.pdf:19.46MB

This report summarizes the activity (FY2000-2003) of Working Group (WG) on Evaluation of Nuclide Generation and Depletion under Subcommittee on Nuclear Fuel Cycle of Japanese Nuclear Data Committee. In the WG, analyses of Post Irradiation Examinations have been carried out for UO$$_{2}$$ and MOX fuels irradiated in PWRs, BWRs and FBRs, and for actinide samples irradiated in fast reactors, by using ORIGEN or more detailed calculation codes with their libraries based on JENDL-3.2, JENDL-3.3 and other foreign nuclear data files. From these results, current prediction accuracy and problems for evaluation of nuclide generation and depletion are discussed. Furthermore, this report covers other products of our activity; development of the ORIGEN libraries for PWR, BWR and FBR based on JENDL-3.3, study on introduction of neutron spectrum index to ORIGEN calculations, and results of questionnaire survey on desirable accuracy of ORIGEN calculations.

JAEA Reports

Research and development on reduced-moderation light water reactor with passive safety features (Contract research)

Iwamura, Takamichi; Okubo, Tsutomu; Akie, Hiroshi; Kugo, Teruhiko; Yonomoto, Taisuke; Kureta, Masatoshi; Ishikawa, Nobuyuki; Nagaya, Yasunobu; Araya, Fumimasa; Okajima, Shigeaki; et al.

JAERI-Research 2004-008, 383 Pages, 2004/06

JAERI-Research-2004-008.pdf:21.49MB

The present report contains the achievement of "Research and Development on Reduced-Moderation Light Water Reactor with Passive Safety Features", which was performed by Japan Atomic Energy Research Institute (JAERI), Hitachi Ltd., Japan Atomic Power Company and Tokyo Institute of Technology in FY2000-2002 as the innovative and viable nuclear energy technology (IVNET) development project operated by the Institute of Applied Energy (IAE). In the present project, the reduced-moderation water reactor (RMWR) has been developed to ensure sustainable energy supply and to solve the recent problems of nuclear power and nuclear fuel cycle, such as economical competitiveness, effective use of plutonium and reduction of spent fuel storage. The RMWR can attain the favorable characteristics such as high burnup, long operation cycle, multiple recycling of plutonium (Pu) and effective utilization of uranium resources based on accumulated LWR technologies.

Journal Articles

Optimal control of ultrafast selection

Yokoyama, Keiichi; Teranishi, Yoshiaki; Toya, Yukio; Shirai, Toshizo; Fukuda, Yuji; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki; Yamakawa, Koichi; et al.

Journal of Chemical Physics, 120(20), p.9446 - 9449, 2004/05

 Times Cited Count:6 Percentile:18.8(Chemistry, Physical)

Optimal laser control for ultrafast selection of closely-lying excited states, whose energy separation is smaller than the laser bandwidth, is reported on the two-photon transition of atomic cesium; Cs(6S $$rightarrow$$ 7D$$_{J}$$, J = 5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yield. After fifty generations, a pair of nearly transform-limitted pulses were obtained as an optimal pulse shape, proving the effectiveness of "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by $$sim$$ 30 % from the simple "Ramsey fringes" experiment.

JAEA Reports

JENDL Dosimetry File 99 (JENDL/D-99)

Kobayashi, Katsuhei*; Iguchi, Tetsuo*; Iwasaki, Shin*; Aoyama, Takafumi*; Shimakawa, Satoshi; Ikeda, Yujiro; Odano, Naoteru; Sakurai, Kiyoshi; Shibata, Keiichi; Nakagawa, Tsuneo; et al.

JAERI 1344, 133 Pages, 2002/01

JAERI-1344.pdf:7.59MB

The JENDL Dosimetry File 99 (JENDL/D-99) has been prepared for determinations of neutron flux/fluence and energy spectrum at specific neutron fields. This file contains data for 67 reactions with 47 nuclides. Cross sections for 33 major dosimetry reactions and their covariance data were simultaneously generated and the other 34 reaction data were mainly adopted from the first version, JENDL/D-91. The GMA code was mainly used for most of the evaluation procedures by referring the basic experimental data in EXFOR. The resultant data are given in the neutron energy region below 20 MeV in both of point-wise and group-wise files in the ENDF-6 format. In order to confirm reliability of the data, several integral tests have been carried out: comparison with the data in IRDF-90V2 and average cross sections measured in fission neutron fields, fast/thermal reactor spectra, DT neutron fields and Li(d,n) neutron fields. The contents of JENDL/D-99 and the results of the integral tests are described in this report. All of the dosimetry cross sections are shown in a graphical form in the Appendix.

JAEA Reports

Reactivity measurement in the JUPITER experiment and Its accuracy

; Aoyama, Takafumi; ; Shirakata, Keisho

JNC TN9400 2001-032, 57 Pages, 2001/01

JNC-TN9400-2001-032.pdf:1.53MB

This report describes the reactivity measurement method and its accuracy employed in ZPPR (Zero Power Physics Reactor) test facility at Argonne National Laboratory, USA. In ZPPR, reactivity measurements were conducted by means of MSM (Modified Neutron Source Multiplication) method using the fission reaction rates by 64 $$^{235}$$U fission chambers which were uniformly located in the core region. The MSM method can evaluate the subcritical reactivity considering the spatial distribution of neutron flux, although its basic equation is the one point approximation reactor dynamic theory. As each detector response varies depending on the core configuration, the uncertainty of the detector response affect directly the accuracy of measured reactivity. Therefore, the average value of many detectors had been conventionally used to reduce the statistical error in the measurerment. In this study, this method was modified to use the linear fitting between measured reaction rates and detector responses. Using this modified method, the uncertainty of each detector response affect the measured reactivity less than the simple averaging method. This new method was verified by applying to the ZPPR control rod worth measurements. It was found that the ratios of neutron source intensities and detector responses could be corrected accurately by the linear fitting in case of reactivity change without or with little fuel movement such as a unit control rod worth measurement.

Oral presentation

Development of a neutron H$$_{p}$$(10) reference monitor for field calibration of personal neutron dosemeters

Tsujimura, Norio; Yoshida, Tadayoshi; Nunomiya, Tomoya*; Aoyama, Kei*

no journal, , 

no abstracts in English

47 (Records 1-20 displayed on this page)