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Journal Articles

Free-surface flow simulations with floating objects using lattice Boltzmann method

Watanabe, Seiya*; Kawahara, Jun*; Aoki, Takayuki*; Sugihara, Kenta; Takase, Shinsuke*; Moriguchi, Shuji*; Hashimoto, Hirotada*

Engineering Applications of Computational Fluid Mechanics, 17(1), p.2211143_1 - 2211143_23, 2023/00

https://doi.org/10.1080/19942060.2023.2211143
 Times Cited Count：1 Percentile：56.82(Engineering, Multidisciplinary)

In tsunami inundations or slope disasters of heavy rain, a lot of floating debris or driftwood logs are included in the flows. The damage to structures from solid body impacts is more severe than the damage from the water pressure. In order to study free-surface flows that include floating debris, developing a high-accurate simulation code of free-surface flows with high performance for large-scale computations is desired. We propose the single-phase free-surface flow model based on the cumulant lattice Boltzmann method coupled with a particle-based rigid body simulation. The discrete element method calculates the contact interaction between solids. An octree-based AMR (Adaptive Mesh Refinement) method is introduced to improve computational accuracy and time-to-solution. High-resolution grids are assigned near the free surfaces and solid boundaries. We conducted two kinds of tsunami flow experiments in the 15 and 70 m water tanks at Hachinohe Institute of Technology and Kobe University to validate the accuracy of the proposed model. The simulation results have shown good agreement with the experiments for the drifting speed, the number of trapped wood pieces, and the stacked angles.

Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

https://doi.org/10.1103/PhysRevLett.124.212502
 Times Cited Count：14 Percentile：73.46(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

JAEA Reports

Proceedings of the 21st Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-XXI); Sep. 29 - Oct.3, 2014, Ibaraki Prefectural Center, Mito, Japan

Oku, Takayuki; Nakamura, Mitsutaka; Sakai, Kenji; Teshigawara, Makoto; Tatsumoto, Hideki*; Yonemura, Masao*; Suzuki, Junichi*; Arai, Masatoshi*

JAEA-Conf 2015-002, 660 Pages, 2016/02

JAEA-Conf-2015-002.pdf:168.34MB

The twenty first meeting of the International Collaboration on Advanced Neutron Source (ICANS-XXI) was held at Ibaraki Prefectural Culture Center in Mito from 29 September to 3 October 2014. It was hosted by Japan Atomic Energy Agency (JAEA), High Energy Accelerator Research Organization (KEK) and Comprehensive Research Organization for Science and Society (CROSS). In the meeting, new science and technology in the new era with the high power neuron sources were discussed in mostly "workshop style" sessions. In each session, various kinds of issues related to not only the hardware, but also the software and even radiation safety were discussed with the keyword of "INTERFACE". More than 200 Papers were presented in the meeting and 72 contributed papers are compiled in the proceedings.

Journal Articles

Development status of the NMR system for the polarized $$^{3}$$He Neutron Spin Filter (NSF) in the MLF at J-PARC

Sakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi*; Kira, Hiroshi*; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Shinohara, Takenao; et al.

JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09

https://doi.org/10.7566/JPSCP.8.036015

The polarized $$^{3}$$He filter, which polarizes neutrons due to a large neutron absorption cross section of $$^{3}$$He with strong spin selectivity, becomes a convenient neutron spin filter (NSF) because it is operated immediately after its installation in beam lines without any neutron beam adjustments. For realizing such the NSF, a nuclear magnetic resonance (NMR) system is indispensable for monitoring $$^{3}$$He nuclear spin polarization ${it P}$ of the NSF. We have developed the flexible NMR system based on adiabatic fast passage (AFP) and pulse NMR methods by using their complementary features. In comparing with the values of ${it P}$ obtained by neutron transmission measurement at the beam line 10 of the J-PARC, we measured the correlations between the AFP and pulse NMR signals as changing condition of temperature, amplitude and applying period of the radio frequency field for the pulse NMR, and so on. As the results, we confirmed that our system would function enough as the ${it P}$ monitor.

Journal Articles

Negative-U system of carbon vacancy in 4H-SiC

Son, N. T.*; Trinh, X. T.*; L${o}$vile, L. S.*; Svensson, B. G.*; Kawahara, Kotaro*; Suda, Jun*; Kimoto, Tsunenobu*; Umeda, Takahide*; Isoya, Junichi*; Makino, Takahiro; et al.

Physical Review Letters, 109(18), p.187603_1 - 187603_5, 2012/11

https://doi.org/10.1103/PhysRevLett.109.187603
 Times Cited Count：201 Percentile：97.98(Physics, Multidisciplinary)

JAEA Reports

A Target-moderator-reflector concept of the JAERI 5MW pulsed spallation neutron source

Watanabe, Noboru*; Teshigawara, Makoto*; Aizawa, Kazuya; Suzuki, Junichi; Oyama, Yukio

JAERI-Tech 98-011, 15 Pages, 1998/03

JAERI-Tech-98-011.pdf:1.02MB

no abstracts in English

Journal Articles

Next generation neutron source project in Japan Atomic Energy Reserch Institute(JAERI)

Yamada, Yasusada*; Watanabe, Noboru*; Niimura, Nobuo; Morii, Yukio; Katano, Susumu; Aizawa, Kazuya; Suzuki, Junichi; Koizumi, Satoshi; Osakabe, Toyotaka; Teshigawara, Makoto*; et al.

Physica B; Condensed Matter, 241-243, p.42 - 45, 1998/00

https://doi.org/10.1016/S0921-4526(97)00508-5
 Times Cited Count：4 Percentile：33.02(Physics, Condensed Matter)

no abstracts in English

Oral presentation

Development and application of an in-situ SEOP $$^{3}$$He neutron spin filter

Oku, Takayuki; Hayashida, Hirotoshi; Sakai, Kenji; Shinohara, Takenao; Nakamura, Mitsutaka; Aizawa, Kazuya; Arai, Masatoshi; Endo, Yasuo; Kakurai, Kazuhisa; Kira, Hiroshi*; et al.

no journal, , 

We have been developing an in-situ SEOP $$^{3}$$He neutron spin filter to apply it to pulsed neutron experiments at J-PARC/MLF. To introduce the $$^{3}$$He neutron spin filter into the instruments of the pulsed neutron facility such as J-PARC/MLF, it is important to make the system compact and stable, because the system is located inside thick and bulky radiation shields for high energy $$gamma$$ ray and neutrons. In this study, we have developed a compact laser optics with a volume holographic grating (VHG) element, and composed an in-situ SEOP $$^{3}$$He neutron spin filter. We have started to apply the $$^{3}$$He spin filer as an analyzer to polarized neutron small angle scattering and reflection measurements. A magnetic field imaging are also being tested with the two $$^{3}$$He neutron spin filter cells which are polarized by the ex-situ SEOP technique. In this paper, we report the design of our SEOP $$^{3}$$He neutron spin filter system and some results of the related polarized neutron beam experiments.

Oral presentation

Development status of NMR monitor for polarized $$^{3}$$He spin filter at J-PARC/MLF

Sakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi; Kira, Hiroshi*; Okawara, Manabu*; Shinohara, Takenao; Oikawa, Kenichi; Harada, Masahide; Kakurai, Kazuhisa; Aizawa, Kazuya; et al.

no journal, , 

A polarized $$^{3}$$He spin filter, which polarizes neutrons due to a large neutron absorption cross section of $$^{3}$$He with strong spin selectivity, works as a simple and convenient neutron spin polarizer. For realizing this filter, a device which monitors a polarization of $$^{3}$$He spin filter is indispensable. We developed the $$^{3}$$He polarization monitor based on a nuclear magnetic resonance method by an adiabatic fast passage (AFP NMR) at the MLF of J-PARC. The monitor based on the AFP NMR realizes the polarized $$^{3}$$He spin flipper functioning as the neutron spin polarizer and flipper. However it has disadvantages on the size of $$^{3}$$He cell limited by a RF coil and its complicated device structure. So we have developed the monitor based on a pulse NMR which uses only a pick up coil and enables the simple device structure of its own, and realized the more flexible monitor system by utilizing the both of pulse NMR and AFP NMR.

Oral presentation

Magnetic shield design of in-situ SEOP polarized $$^{3}$$He neutron spin filter for high magnetic field sample environment accessories at J-PARC

Kira, Hiroshi*; Hayashida, Hirotoshi*; Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Suzuki, Junichi*; et al.

no journal, , 

Oral presentation

Development of a $$^{3}$$He nuclear spin flip system for the in-situ SEOP $$^{3}$$He filter

Hayashida, Hirotoshi*; Kira, Hiroshi*; Suzuki, Junichi*; Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Shinohara, Takenao; Kakurai, Kazuhisa; Aizawa, Kazuya; Arai, Masatoshi; et al.

no journal, , 

no abstracts in English

Oral presentation

Development status and future plan of a $$^3$$He neutron spin filter

Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Shinohara, Takenao; Aizawa, Kazuya; Arai, Masatoshi; Kakurai, Kazuhisa; Hayashida, Hirotoshi*; Kira, Hiroshi*; Suzuki, Junichi*; et al.

no journal, , 

no abstracts in English

Oral presentation

Development status and future plan of a $$^{3}$$He neutron spin filter

Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Shinohara, Takenao; Aizawa, Kazuya; Kakurai, Kazuhisa; Kira, Hiroshi*; Hayashida, Hirotoshi*; Kiriyama, Koji*; Suzuki, Junichi*; et al.

no journal, , 

We have been developing a $$^{3}$$He neutron spin filter for application at J-PARC MLF. The $$^{3}$$ neutron spin filter is available for neutrons in a wide energy range, and is also effective for a divergent neutron beam. Therefore, it is very useful in the neutron scattering experiment. So far, we have developed a compact laser optics with a volume holographic grating (VHG) elements, and have constructed an on-beam SEOP based $$^{3}$$He neutron spin filter. The polarization analysis tests were performed with the $$^{3}$$He neutron spin filter at several neutron beamlines for the sans, reflectivity and neutron imaging experiments. To extend the application range of the $$^{3}$$He neutron spin filter at J-PARC MLF, we plan to develop larger size cells, higher power laser for the SEOP, and prepare working area for the filter inside the MLF experimental hall.

Oral presentation

Current status and future plan of a $$^{3}$$He spin filter development

Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Watanabe, Masao; Shinohara, Takenao; Aizawa, Kazuya; Kakurai, Kazuhisa; Kira, Hiroshi*; Hayashida, Hirotoshi*; Kiriyama, Koji*; et al.

no journal, , 

We have been developing a $$^{3}$$He neutron spin filter for applicaion at J-PARC MLF. The $$^{3}$$He neutron spin filter is avairable for neutrons in a wide energy range, and is also effective for a divergent neutron beam. Therefore, it is very useful in the neutron scattering experiment. So far, we have devleoped a compact laser optics with a volume holographic grating (VHG) elements, and have constructed an on-beam SEOP based $$^{3}$$He neutron spin filter. The olarization analysis tests were performed with the $$^{3}$$He neutron spin filter at several neutron beamlines for the sans, reflectivity and neutron imaging experiments. To extend the application range of the $$^{3}$$He neutron spin filter at J-PARC MLF, we plan to develop larger saize cells, higher power laser for the SEOP, and prepare working area for the filter inside the MLF experimental hall.

Oral presentation

Current status of a $$^{3}$$He spin filter development

Oku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Watanabe, Masao; Shinohara, Takenao; Aizawa, Kazuya; Kakurai, Kazuhisa*; Kira, Hiroshi*; Hayashida, Hirotoshi*; Kiriyama, Koji*; et al.

no journal, , 

We have been developing a $$^{3}$$He neutron spin filter for application at J-PARC MLF. The $$^{3}$$He neutron spin filter is available for neutrons in a wide energy range, and is also effective for a divergent neutron beam. Therefore, it is very useful in the neutron scattering experiment. So far, we have developed a compact laser optics with a volume holographic grating (VHG) elements, and have constructed an on-beam SEOP based $$^{3}$$He neutron spin filter. The polarization analysis tests were performed with the $$^{3}$$He neutron spin filter at several neutron beamlines for the sans, reflectivity and neutron imaging experiments. To extend the application range of the $$^{3}$$He neutron spin filter at J-PARC MLF, we plan to develop larger size cells, higher power laser for the SEOP, and prepare working area for the filter inside the MLF experimental hall.

15 (Records 1-15 displayed on this page)
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