Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 46

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:3 Percentile:80.29(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

The $$f$$-electron state of the heavy fermion superconductor NpPd$$_5$$Al$$_2$$ and the isostructural family

Metoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagihara, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03

Rare earths (4$$f$$) and actinides (5$$f$$) provide variety of interesting states realized with competing interactions between the increasing number of $$f$$ electrons. Since crystal field splitting of many-body $$f$$ electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the $$f$$ electron states of heavy electron compounds NpPd$$_5$$Al$$_2$$ and actinide and rare earth based iso-structural family.

Journal Articles

Present status of personnel protection system at J-PARC

Kikuzawa, Nobuhiro; Niki, Kazuaki*; Yamamoto, Noboru*; Hayashi, Naoki; Adachi, Masatoshi*; Watanabe, Kazuhiko*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.877 - 880, 2019/07

Interlock system of J-PARC is classified into a personnel protection system (PPS) for human safety and a machine protection system (MPS) for protecting equipment. The PPS of the J-PARC accelerator started from the operation at Linac in 2006 and was completed by the MR operation in 2008. In the next 10 years, some improvements have been made, such as updating video monitoring systems and establishing new interlocks. In addition to describing recent operations including these updatings, this paper reports the current status of inspections and maintenance conducted to maintain and improve reliability.

Journal Articles

22A beam production of the uniform negative ions in the JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Hatayama, Akiyoshi*; Shibata, Takanori*; Yamamoto, Takashi*; Akino, Noboru; Endo, Yasuei; et al.

Fusion Engineering and Design, 96-97, p.616 - 619, 2015/10

 Times Cited Count:11 Percentile:67.6(Nuclear Science & Technology)

In JT-60 Super Advanced for the fusion experiment, 22A, 100s negative ions are designed to be extracted from the world largest ion extraction area of 450 mm $$times$$ 1100 mm. One of the key issues for producing such as high current beams is to improve non-uniform production of the negative ions. In order to improve the uniformity of the negative ions, a tent-shaped magnetic filter has newly been developed and tested for JT-60SA negative ion source. The original tent-shaped filter significantly improved the logitudunal uniformity of the extracted H$$^{-}$$ ion beams. The logitudinal uniform areas within a $$pm$$10 deviation of the beam intensity were improved from 45% to 70% of the ion extraction area. However, this improvement degrades a horizontal uniformity. For this, the uniform areas was no more than 55% of the total ion extraction area. In order to improve the horizontal uniformity, the filter strength has been reduced from 660 Gasus$$cdot$$cm to 400 Gasus$$cdot$$cm. This reduction improved the horizontal uniform area from 75% to 90% without degrading the logitudinal uniformity. This resulted in the improvement of the uniform area from 45% of the total ion extraction areas. This improvement of the uniform area leads to the production of a 22A H$$^{-}$$ ion beam from 450 mm $$times$$ 1100 mm with a small amount increase of electron current of 10%. The obtained beam current fulfills the requirement for JT-60SA.

Journal Articles

Development of a compact vertical splitting system for the cold neutron beam at JRR-3

Tamura, Itaru; Maruyama, Ryuji; Yamazaki, Dai; Nakamura, Kiyoshi; Yamamoto, Kazuyoshi; Aizawa, Kazuya; Soyama, Kazuhiko

Journal of Physics; Conference Series, 528, p.012012_1 - 012012_7, 2014/07

 Times Cited Count:1 Percentile:52.39

To achieve efficient implementation of usage of neutron beam instruments, the instruments were rearranged at C2 cold neutron beam line at JRR-3 by using a newly developed compact vertical splitting system. The splitting system has two compact multi channel benders. The bender has been developed using Ni/Ti supermirrors coated on both sides of 0.2 mm thickness silicon substrates. The curvature radius of the bender is 938 mm and the length of the bender is 320 mm yielding deflection angles of 20$$^{circ}$$. Supermirrors with m=3 were deposited on both sides of silicon substrate by an ion beam sputtering apparatus in JAEA. Neutron flux at the end of the neutron guide that installed at the bender exit of which the deflection angle is 20$$^{circ}$$ was measured by the gold foil activation method. It was measured 1.58 $$times$$ 10$$^{7}$$ n/cm$$^{2}$$/s. The present study showed that the supermirrors coated on both sides with high reflectivity are suitable for the compact bender.

JAEA Reports

Result and considerations on the pre-excavation grouting below four hundreds meter depth of the ventilation shaft

Ishii, Yoji; Watanabe, Kazuhiko; Kamiya, Akira; Hayano, Akira; Mikake, Shinichiro; Takeuchi, Shinji; Ikeda, Koki; Yamamoto, Masaru; Sugihara, Kozo

JAEA-Technology 2010-044, 92 Pages, 2011/02

JAEA-Technology-2010-044.pdf:11.73MB

The "Mizunami Underground Research Laboratory" has been carrying out scientific research in granite to establish the technological basis for high-level radioactive waste disposal. To get reliable information on the rock mass geology and hydrogeology and on the bedrock conditions, a pilot borehole investigation was carried out before sinking the ventilation shaft. During this investigation, a zone with high hydraulic head and low hydraulic conductivity was observed at around GL-400m. To reduce water inflow during excavation, pre-excavation grouting with micro-fine cement was done in this region before sinking the Ventilation Shaft. Despite the high hydraulic head and the low hydraulic conductivity, effective reduction of water-inflow was achieved.

Journal Articles

Reconstruction of the 2-dimensitonal beam profile at longitudinal phase space with tomography method in J-PARC RCS and MR

Yoshimoto, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Hayashi, Naoki; Kawase, Masato; Watanabe, Kazuhiko*; Yoshikawa, Muneyoshi*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.737 - 740, 2010/03

The longitudinal phase space tomography, which was evolved to retrieve the two-dimensional beam distribution in the longitudinal phase space with computer tomography algorithms, is very useful diagnostic tool in the accelerator domain. The simple reconstruction tool was developed for the J-PARC RCS and MR with the convolution back projection method for the beam storage mode. On the assumption that the longitudinal profiles should not be disturbed for one period of the synchrotron oscillation, such two-dimensional profiles can be reconstructed easily from one-dimensional bunch beam profiles, which are measured for every turn by the wall current monitor.

Journal Articles

The Electrochemical impedance spectroscopy of stainless steel exposed to high temperature water containing hydrogen peroxide

Sato, Tomonori; Noda, Kazuhiko*; Kato, Chiaki; Yamamoto, Masahiro; Nakano, Junichi; Tsukada, Takashi

Proceedings of Symposium on Water Chemistry and Corrosion in Nuclear Power Plants in Asia 2009 (CD-ROM), p.232 - 237, 2009/10

In this work, to clarify the electrochemical behaviors at the surfaces of stainless steels (SSs) in high temperature water containing hydrogen peroxide (H$$_{2}$$O$$_{2}$$), the in-situ electrochemical impedance spectroscopy (EIS) of SSs exposed to high temperature water was carried out. The materials of test specimens were type 316L SS and type 304L SS. The range of the applied frequency in EIS was 100 kHz to 1 m or 10 mHz. The charge transfer resistance at the boundary between the oxide film and the base metal (R$$_{rm ct}$$) in oxygen (O$$_{2}$$) condition was larger than R$$_{rm ct}$$ in H$$_{2}$$O$$_{2}$$ condition. This indicates that the corrosion rate of type 316L SS in high temperature water containing H$$_{2}$$O$$_{2}$$ is larger than that in O$$_{2}$$ contained water. The R$$_{rm ct}$$ of type 316L SS was larger than that of type 304L SS in high temperature water containing H$$_{2}$$O$$_{2}$$. This indicates that the corrosion resistance of type 316L SS is higher than that of type 304L SS.

Journal Articles

Longitudinal phase space tomography at J-PARC RCS

Yoshimoto, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Hayashi, Naoki; Kawase, Masato; Watanabe, Kazuhiko*; Yoshikawa, Hirokazu*

Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.3358 - 3360, 2009/05

The longitudinal phase space tomography, which was evolved to retrieve the two-dimensional beam distribution in the longitudinal phase space with computer tomography algorithms, is very useful diagnostic tool in the accelerator domain. The simple reconstruction tool was developed for the J-PARC RCS with the convolution back projection method for the beam storage mode. On the assumption that the longitudinal profiles should not be disturbed for one period of the synchrotron oscillation, such two-dimensional profiles can be reconstructed easily from one-dimensional bunch beam profiles, which are measured for every turn by the wall current monitor.

Journal Articles

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

 Times Cited Count:51 Percentile:71.37(Biochemistry & Molecular Biology)

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

JAEA Reports

Research for the life-extension of the wide-range monitoring neutron detectors of HTTR (Joint research)

Saito, Kenji; Sekita, Kenji; Kawasaki, Kozo; Yamamoto, Kazuhiko*; Matsuura, Makoto*

JAEA-Technology 2007-059, 36 Pages, 2007/11

JAEA-Technology-2007-059.pdf:26.24MB

The Wide-Range Monitoring neutron detectors of HTTR are used under 450 $$^{circ}$$C in normal operation and 550 $$^{circ}$$C in the accidents. When the WRM detectors are used under the high temperature for a long time, characteristics of the detector might be degraded, because of the decrease of the nitrogen concentration in the ionization gas caused by adsorbtion of nitrogen into the electrode material. Consequently, the nitrogen gas adsorption test was carried out to clarify the quantity of absorbed nitrogen gas in electrode material under the high temperature. Then, the performance evaluation test of the prototype detector was carried out, and it was confirmed that degradation of the prototype detector characteristics didn't arise under the high temperature anvironment. This report describes the results of consideration about the life-extension of WRM detectors. As a result, it was confirmed that the WRM detectors are usable for 5 years under 450 $$^{circ}$$C in normal operation and 550 $$^{circ}$$C in the accidents.

Journal Articles

Current status of the control system for J-PARC accelerator complex

Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.

Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10

J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.

Journal Articles

Present status of the negative ion based NBI system for long pulse operation on JT-60U

Ikeda, Yoshitaka; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kawai, Mikito; Kazawa, Minoru; et al.

Nuclear Fusion, 46(6), p.S211 - S219, 2006/06

 Times Cited Count:58 Percentile:87.29(Physics, Fluids & Plasmas)

Recently, the extension of the pulse duration up to 30 sec has been intended to study quasi-steady state plasma on JT-60U N-NBI system. The most serious issue is to reduce the heat load on the grids for long pulse operation. Two modifications have been proposed to reduce the heat load. One is to suppress the beam spread which may be caused by beamlet-beamlet interaction in the multi-aperture grid due to the space charge force. Thin plates were attached on the extraction grid to modify the local electric field. The plate thickness was optimized to steer the beamlet deflection. The other is to reduce the stripping loss, where the electron of the negative ion beam is stripped and accelerated in the ion source and then collides with the grids. The ion source was modified to reduce the pressure in the accelerator column to suppress the beam-ion stripping loss. Up to now, long pulse injection of 17 sec for 1.6 MW and 25 sec for $$sim$$1 MW has been obtained by one ion source with these modifications.

Journal Articles

Acceleration of high current fully stripped carbon ion beam by direct injection scheme

Kashiwagi, Hirotsugu; Fukuda, Mitsuhiro; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; et al.

Review of Scientific Instruments, 77(3), p.03B305_1 - 03B305_4, 2006/03

 Times Cited Count:12 Percentile:52.35(Instruments & Instrumentation)

Acceleration of a 17mA 100keV/u C$$^{6+}$$ ion beam has been successfully achieved with an RFQ linac by means of "Direct injection scheme". The Direct injection scheme is a new scheme for injecting an ion beam from a laser ion source to the RFQ linac without a low energy beam transport line to avoid a beam loss due to the space charge effect. The high current C$$^{6+}$$ beam is required for single turn injection to a synchrotron to reduce the size of synchrotron magnets. The high current C$$^{6+}$$ beam produced by an ion source with a Nd-YAG laser was injected to the RFQ linac by the Direct injection scheme. It has been proved experimentally that the fully-stripped carbon ion beam with a current more than 10mA can be accelerated by the RFQ linac.

Journal Articles

High current carbon beam production with direct plasma injection scheme

Okamura, Masahiro*; Kashiwagi, Hirotsugu; Sakakibara, Kazuhiko*; Takano, Jumpei*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Jameson, R. A.*; Yamamoto, Kazuo*

Review of Scientific Instruments, 77(3), p.03B303_1 - 03B303_3, 2006/03

 Times Cited Count:10 Percentile:47.17(Instruments & Instrumentation)

We have been studying a new heavy-ion production technique called "direct plasma injection scheme", DPIS, since 2000. A new radio frequency quadrupole "RFQ" designed especially for the DPIS was commissioned in 2004 and very intense carbon beam was successfully obtained, reaching more than 60 mA accelerated current from the RFQ. Most of the contents of the accelerated beam was carbon 4+ as verified by beam analysis.

Journal Articles

Recent progress of negative ion based neutral beam injector for JT-60U

Umeda, Naotaka; Yamamoto, Takumi; Hanada, Masaya; Grisham, L. R.*; Kawai, Mikito; Oga, Tokumichi; Akino, Noboru; Inoue, Takashi; Kazawa, Minoru; Kikuchi, Katsumi*; et al.

Fusion Engineering and Design, 74(1-4), p.385 - 390, 2005/11

 Times Cited Count:9 Percentile:53.26(Nuclear Science & Technology)

In negative ion based neutral beam injector (N-NBI) for JT-60U, some modifications for extent pulse duration from 10 second, which is design value, to 30 second was conducted. Main limit to prevent pulse extension was heat loads onto grounded grid in an ion source and onto beam limiter placed at 22 m from the ion source. To reduce these heat loads, beam extraction area was optimized and the limiter was changed to one which had about twice thermal capacity. As a result of these modifications, the temperature rise of the water which was cooling grounded grid could be suppressed under 40 degree, which can operate in steady state condition. The temperature rise of the limiter could be restricted to 60%. Untill now the beam pulse extended to 17 second of 1.6MW power at 366keV energy, and injection of 30 seconds will be achieved in next experiment.

Journal Articles

Acceleration of high current and highly charged carbon beam using direct injection scheme

Kashiwagi, Hirotsugu; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; Fujimoto, Tetsuya*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.182 - 184, 2005/07

The carbon beam from a Nd-YAG laser ion source was accelerated successfully by an RFQ linac using Direct injection scheme. The "Direct injection scheme" is the way to inject an ion beam to the RFQ linac without a low energy beam transport line to avoid space charge effect due to a high intensity beam from the laser ion source. About 30mA of a carbon beam was detected by a faraday cup just behind the RFQ linac.

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.

JAEA Reports

Summary of the data which is used for radionuclide transport analysis in the groundwater

Koga, Osamu; Nagara, Shuichi; Matsumura, Toshihiro; Takeuchi, Akira*; Takeda, Shinji; Yamamoto, Masahiro*; Sato, Kazuhiko

JNC TN6440 2004-003, 66 Pages, 2004/03

JNC-TN6440-2004-003.pdf:1.95MB

To analyze high precision in groundwater flow and radionuclide transport around Yotsugi open-pit mining place site and around Yotsugi mill tailing yard, besides the topic in past analysis is extracted, following it did examination of the corresponding method and arrangement of physical properties value.

JAEA Reports

Measurement of radon concentration in groundwater around Yotsugi open pit site

Nagara, Shuichi; Yamamoto, Masahiro*; Koga, Osamu; Takeuchi, Akira; Matsumura, Toshihiro; Takeda, Shinji; Sato, Kazuhiko

JNC TN6420 2004-001, 75 Pages, 2004/03

JNC-TN6420-2004-001.pdf:2.93MB

The radon concentration in groundwater summarized around the Yotsugi open-pit site has been measured from 2002 to 2003 and examined radon observation system built in 2001. Moreover, the maintenance actual result of the radon observation system was summarized.

46 (Records 1-20 displayed on this page)