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Journal Articles

Kinetic inductance neutron detector operated at near critical temperature

Vu, TheDang; Nishimura, Kazuma*; Shishido, Hiroaki*; Harada, Masahide; Oikawa, Kenichi; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; Soyama, Kazuhiko; Aizawa, Kazuya; et al.

Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07

Journal Articles

Measurement of prompt neutron decay constant with spallation neutrons at Kyoto University Critical Assembly using linear combination method

Katano, Ryota; Yamanaka, Masao*; Pyeon, C. H.*

Journal of Nuclear Science and Technology, 57(2), p.169 - 176, 2020/02

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

We proposed the linear combination method as a subcriticality measurement method which estimates the prompt neutron decay constant ($$alpha$$) correlated with the subcriticality using measurement results obtained at multiple detector positions. In the previous study, we confirmed applicability of the linear combination method through the pulsed neutron experiment with DT neutron source at Kyoto University Critical Assembly (KUCA). In this study, we conduct the pulsed neutron source experiment with spallation neutrons at KUCA and confirm the robustness of the linear combination to neutron sources.

Journal Articles

Application of linear combination method to pulsed neutron source measurement at Kyoto University Critical Assembly

Katano, Ryota; Yamanaka, Masao*; Pyeon, C. H.*

Nuclear Science and Engineering, 193(12), p.1394 - 1402, 2019/12

 Times Cited Count:2 Percentile:31.52(Nuclear Science & Technology)

The author proposed the linear combination method as a subcriticality measurement method which estimates the prompt neutron decay constant (alpha) correlated with the subcriticality using measurement results obtained at multiple detector positions. In this study, we conduct the pulsed neutron experiment at Kyoto University Critical Assembly (KUCA) and measure alpha by the linear combination method using measured neutron counts. Through experiment, we experimentally show that the linear combination method can reduce the higher-mode effect compared to the conventional method. In addition, experimentally show that the linear combination has capability of the different mode extraction.

JAEA Reports

Improvement of accumulator in cryogenic hydrogen system used for 1-MW pulsed spallation neutron source

Aso, Tomokazu; Tatsumoto, Hideki*; Otsu, Kiichi*; Kawakami, Yoshihiko*; Komori, Shinji*; Muto, Hideki*; Takada, Hiroshi

JAEA-Technology 2019-013, 77 Pages, 2019/09


At Materials and Life Science experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), a 1-MW pulsed spallation neutron source is equipped with a cryogenic hydrogen system which circulates liquid hydrogen (20 K and 1.5 MPa) to convert high energy neutrons generated at a mercury target to cold neutrons at three moderators with removing nuclear heat of 3.8 kW deposited there. The cryogenic system includes an accumulator with a bellows structure in order to absorb pressure fluctuations generated by the nuclear heat deposition in the system. Welded inner bellows of the first accumulator was failured during operation, forcing us to improve the accumulator to have sufficient pressure resistance and longer life-time. We have developed elemental technologies for manufacturing welded bellows of the accumulator by a thick plate with high pressure resistance, succeeding to find optimum welding conditions. We fabricated a prototype bellows block and carried out an endurance test by adding a pressure change of 2 MPa repeatedly. As a result, the prototype bellows was successfully in use exceeding the design life of 10,000 times. Since distortions given during welding and assembling affect functionality and lifetime of the bellows, we set the levelness of each element of the bellows as within 0.1$$^{circ}$$. The improved accumulator has already been in operation for about 25,000 hours as of January 2019, resulting that the number of strokes reached to 16,000. In July 2018, we demonstrated that the accumulator could suppress the pressure fluctuation generated by the 932 kW beam injection as designed. As current operational beam power is 500 kW, the current cryogenic hydrogen system could be applicable for stable operation at higher power in the future.

Journal Articles

Area ratio method via linear combination of the neutron counts in pulsed neutron experiment

Katano, Ryota

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05

no abstracts in English

Journal Articles

Estimation method of prompt neutron decay constant reducing higher order mode effect by linear combination

Katano, Ryota

Nuclear Science and Engineering, 193(4), p.431 - 439, 2019/04

 Times Cited Count:3 Percentile:18.47(Nuclear Science & Technology)

We proposed "linear combination method" to reduce the higher order mode effect on the prompt neutron decay constant measured by the pulsed neutron experiment. When the spatial higher order mode effect is taken into account, the time evolution of the neutron counts after the pulsed neutron injection is given by linear combination of multiple exponential functions. However, the measurement results by the conventional method include the systematic error derived from the higher order mode effect because the conventional method fit the neutron counts with a single exponential function. The proposed method extract the single exponential function of the fundamental mode by linear combination of the neutron counts at multiple detectors, thus the proposed method reduces the higher order mode effect. As the verification, we applied the proposed method to the numerical simulation. The results indicate that the proposed method can reduce the higher order mode effect by linear combination.

Journal Articles

Fundamental aspects of neutron moderators and neutron beam optics for designing high intensity laser-driven neutron source

Ikeda, Yujiro; Shimizu, Hirohiko*

Reza Kenkyu, 46(11), p.641 - 646, 2018/11

In viewing significant progresses in technical achievement toward a high-intensity neutron source driven by a high-power laser came up with the high power laser development, we have reviewed the currently most advanced moderator system and neutron optics, which are the key elements for the neutron beam applications. Regarding the moderators, concepts adopted in J-PARC pulsed neutron source, which is one of most advanced system, were described to give a baseline design. Also a new direction of moderator concept is shown, which could be a high brightness candidate for the high-intensity laser driven system. On the neutron optics, the most fundamental consideration is primarily reviewed along with recent progress in new devises for enrichment of neutron-beam characteristics.

Journal Articles

Experimental validation of the brightness distribution on the surfaces of coupled and decoupled moderators composed of 99.8% parahydrogen at the J-PARC pulsed spallation neutron source

Harada, Masahide; Teshigawara, Makoto; Oi, Motoki; Klinkby, E.*; Zanini, L.*; Batkov, K.*; Oikawa, Kenichi; Toh, Yosuke; Kimura, Atsushi; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 903, p.38 - 45, 2018/09

 Times Cited Count:4 Percentile:27.98(Instruments & Instrumentation)

Journal Articles

Implementation of a low-activation Au-In-Cd decoupler into the J-PARC 1 MW short pulsed spallation neutron source

Teshigawara, Makoto; Ikeda, Yujiro; Oi, Motoki; Harada, Masahide; Takada, Hiroshi; Kakishiro, Masanori*; Noguchi, Gaku*; Shimada, Tsubasa*; Seita, Kyoichi*; Murashima, Daisuke*; et al.

Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

We developed an Au-In-Cd (AuIC) decoupler material to reduce induced radioactivity instead of Ag-In-Cd one, which has a cut off energy of 1eV. In order to implement it into an actual moderator-reflector assembly, a number of critical engineering issues need to be resolved with regard to large-sized bonding between AuIC and A5083 alloys by the hot isostatic pressing process. We investigated this process in terms of the surface conditions, sizes, and heat capacities of large AuIC alloys. We also show a successful implementation of an AuIC decoupler into a reflector assembly, resulting in a remarkable reduction of radioactivity by AuIC compared to AIC without sacrificing neutronic performance.

Journal Articles

Analysis of energy resolution in the KURRI-LINAC pulsed neutron facility

Sano, Tadafumi*; Hori, Junichi*; Takahashi, Yoshiyuki*; Yashima, Hiroshi*; Lee, J.*; Harada, Hideo

EPJ Web of Conferences, 146, p.03031_1 - 03031_3, 2017/09

 Times Cited Count:1 Percentile:25.31

Journal Articles

Multiple-wavelength neutron holography with pulsed neutrons

Hayashi, Koichi*; Oyama, Kenji*; Happo, Naohisa*; Matsushita, Tomohiro*; Hosokawa, Shinya*; Harada, Masahide; Inamura, Yasuhiro; Nitani, Hiroaki*; Shishido, Toetsu*; Yubuta, Kunio*

Science Advances (Internet), 3(8), p.e1700294_1 - e1700294_7, 2017/08

Journal Articles

Energy-resolved small-angle neutron scattering from steel

Oba, Yojiro*; Morooka, Satoshi; Oishi, Kazuki*; Suzuki, Junichi*; Takata, Shinichi; Sato, Nobuhiro*; Inoue, Rintaro*; Tsuchiyama, Toshihiro*; Gilbert, E. P.*; Sugiyama, Masaaki*

Journal of Applied Crystallography, 50(2), p.334 - 339, 2017/04

 Times Cited Count:2 Percentile:67.49(Chemistry, Multidisciplinary)

Journal Articles

On-line subcriticality measurement using a pulsed spallation neutron source

Iwamoto, Hiroki; Nishihara, Kenji; Yagi, Takahiro*; Pyeon, C.-H.*

Journal of Nuclear Science and Technology, 54(4), p.432 - 443, 2017/04

 Times Cited Count:14 Percentile:4.91(Nuclear Science & Technology)

Journal Articles

Neutron flux spectrum revealed by Nb-based current-biased kinetic inductance detector with a $$^{10}$$B conversion layer

Miyajima, Shigeyuki*; Shishido, Hiroaki*; Narukami, Yoshito*; Yoshioka, Naohito*; Fujimaki, Akira*; Hidaka, Mutsuo*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi*; et al.

Nuclear Instruments and Methods in Physics Research A, 842, p.71 - 75, 2017/01

 Times Cited Count:9 Percentile:12.6(Instruments & Instrumentation)

Journal Articles

Novel neutron scattering techniques using neutron transmission spectra

Oba, Yojiro*; Morooka, Satoshi; Sato, Hirotaka*; Sato, Nobuhiro*; Inoue, Rintaro*; Sugiyama, Masaaki*

Hamon, 26(4), p.170 - 173, 2016/11

Journal Articles

A Report on the 5th ANNRI Conference

Nakamura, Shoji; Toh, Yosuke; Kimura, Atsushi; Katabuchi, Tatsuya*

Kaku Deta Nyusu (Internet), (115), p.49 - 60, 2016/10

This is a report on the 5th ANNRI conference held at Tokyo Institute of Technology in Ookayama in August 4th, 2016.

Journal Articles

Progress of target system operation at the pulsed spallation neutron source in J-PARC

Takada, Hiroshi; Naoe, Takashi; Kai, Tetsuya; Kogawa, Hiroyuki; Haga, Katsuhiro

Proceedings of 12th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '15), p.297 - 304, 2016/00

In J-PARC, we have continuously been making efforts to operate a mercury target of a pulsed spallation neutron source with rated power of 1-MW. One of technical progresses is to mitigate cavitation damages at the target vessel front induced by the 3-GeV proton beam injection at 25 Hz. We have improved the performance of a gas micro-bubbles injection into the mercury target, resulting that no significant cavitation damages was observed on the inner surface of target vessel after operation for 2050 MWh with the 300-kW proton beam. Another progress is to suppress the release of gaseous radioactive isotopes, especially tritium, during the target vessel replacement. We have introduced a procedure to evacuate the target system by an off-gas processing apparatus when it is opened during the replacement operation, achieving to suppress the tritium release through the stack. For example, the amount of released tritium was 12.5 GBq, only 5.4% of the estimated amount, after the 2050 MWh operation. After these progresses, the operating beam power for the pulsed spallation neutron source was ramped up to 500-kW in April, 2015.

Journal Articles

Minor actinide neutron capture cross-section measurements with a 4$$pi$$ Ge spectrometer

Koizumi, Mitsuo; Osa, Akihiko; Toh, Yosuke; Kimura, Atsushi; Mizumoto, Motoharu; Oshima, Masumi; Igashira, Masayuki*; Osaki, Toshiro*; Harada, Hideo*; Furutaka, Kazuyoshi*; et al.

Nuclear Instruments and Methods in Physics Research A, 562(2), p.767 - 770, 2006/06

 Times Cited Count:6 Percentile:53.98(Instruments & Instrumentation)

In order to measure the neutron capture cross section of minor actinides, we have proposed the use of a 4$$pi$$ Ge spectrometer. A Time-of-Flight neutron beam line for the experiment has been constructed at the KURRI electron LINAC. The assembling of the 4$$pi$$ Ge spectrometer is in progress. We are also developing a new data acquisition system based on a digital processing technique.

Journal Articles

Improved cavitation resistance of structural materials in pulsed liquid metal targets by surface hardening

Koppitz, T.*; Jung, P.*; M$"u$ller, G.*; Weisenburger, A.*; Futakawa, Masatoshi; Ikeda, Yujiro

Journal of Nuclear Materials, 343(1-3), p.92 - 100, 2005/08

 Times Cited Count:7 Percentile:51.34(Materials Science, Multidisciplinary)

Cavitation damage of structural materials due to pressure waves is expected to be one of the majior life-time limiting factors in high power liquid metal spallation targets under pulsed operation. Two methods are developed for the European Spallation Source (ESS) to mitigate this damage: Introduction of gas bubbles to surpress the pressure pulse and surface-hardening of structural materials. Surface-hardening of four 8-13%Cr martenstic steels was examined by thermal treatment with pulsed or scanned electron- and laser-beams as well as by nitriding in plasma. A specimens of the 12%Cr steel were tested in liquid mercury under pulsed proton irradiation, and under mechanical pulsed-loading. Surface damage was analysed by optical, confocal-laser, or scanning-electron microscopy, showing in both tests much better resistance of the hardened material compared to standard condition.

Journal Articles

The Design of the neutron total scattering spectrometer for hydrogenous materials at J-PARC-JSNS

Suzuya, Kentaro; Kameda, Yasuo*; Otomo, Toshiya*; Yoshida, Koji*; Ito, Keiji*; Fukunaga, Toshiharu*; Misawa, Masakatsu*

Journal of Neutron Research, 13(1-3), p.123 - 128, 2005/03

The design, performance, philosophy, lessons learned and advantages of the neutron total scattering spectrometer for hydrogenous materials, FAST, under consideration for the J-PARC-JSNS, are described. In particular, novel instrumentation concept such as the small fractional scattered neutron flight path, $$gamma$$= L$$_{2}$$/(L$$_{1}$$+L$$_{2}$$), where L$$_{1}$$ is the incident flight path, moderator to sample, L$$_{2}$$ is the scattered neutron flight path from sample to detector, is presented and their expected performance at the JSNS is considered.

52 (Records 1-20 displayed on this page)