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Journal Articles

Operation status of the J-PARC high-intensity RF-driven negative hydrogen ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Ueno, Akira

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.928 - 931, 2023/11

J-PARC initiated the operation of the high-intensity rf-driven negative hydrogen (H$$^-$$) ion source in 2014 autumn. The ion source produces the H$$^-$$ beam with the beam current of 60 mA and the beam energy of 50 keV in order to inject the H$$^-$$ beam into the 3 GeV RCS with the beam current of 50 mA and the beam energy of 400 MeV from the J-PARC linac. We have achieved the longest continuous operation time of 4001 hours in the previous (2021/2022) campaign. The 2022/2023 campaign was the first time that the continuous operation of the H$$^-$$ ion source without any exchanges of the ion source until the end of the campaign was examined. We present the operation status of the J-PARC H$$^-$$ ion source in this campaign as well as the status of the J-PARC-made internal antenna test.

Journal Articles

Polarized neutrons observed nanometer-thick crystalline ice plates in frozen glucose solution

Kumada, Takayuki; Nakagawa, Hiroshi; Miura, Daisuke; Sekine, Yurina; Motokawa, Ryuhei; Hiroi, Kosuke; Inamura, Yasuhiro; Oku, Takayuki; Oishi, Kazuki*; Morikawa, Toshiaki*; et al.

Journal of Physical Chemistry Letters (Internet), 14(34), p.7638 - 7643, 2023/08

The structure of nano-ice crystals in rapidly frozen glucose solution was elucidated by using spin-contrast-variation small-angle neutron scattering, which distinguishes the nano-ice crystal signal from the frozen amorphous solution signal by the polarization-dependent neutron scattering. The analysis revealed that the nano-ice crystals form a planar structure with a diameter exceeding tens of nanometers and a thickness of 1 nm, which is close to the critical nucleation size. This result suggests that the glucose molecules are preferentially bound to a specific face of nano-ice crystals, and then block the crystal growth perpendicular to that face.

Journal Articles

Effect of water activity on the mechanical glass transition and dynamical transition of bacteria

Sogabe, Tomochika*; Nakagawa, Hiroshi; Yamada, Takeshi*; Koseki, Shigenobu*; Kawai, Kiyoshi*

Biophysical Journal, 121(20), p.3874 - 3882, 2022/10

 Times Cited Count:1 Percentile:21.24(Biophysics)

The purpose of this study was to clarify the glass transition behavior of bacteria ($$Cronobacter sakazakii$$) as a function of water activity ($$a_{rm w}$$). Mechanical relaxation was investigated at 298 K, and the mechanical $$a_{rm wc}$$ ($$a_{rm w}$$ at which mechanical glass transition occurs at 298 K) was determined to be 0.667. Temperature-dependency of mean square displacement was investigated by inelastic neutron scattering. From the linear fitting, two dynamical transition temperatures (low and high-$$T_{rm ds}$$) were determined. There was a minor effect of $$a_{rm w}$$ on the low-$$T_{rm ds}$$ except for the anhydrous sample. The high-$$T_{rm ds}$$ largely increased with the decrease in $$a_{rm w}$$. The dynamical $$a_{rm wc}$$determined by high-$$T_{rm ds}$$ (0.688) was slightly higher than the mechanical $$a_{rm wc}$$ because of the difference in the measurement time-scale. The high-$$T_{rm ds}$$ was converted to the glass transition temperature ($$T_{rm g}$$), and anhydrous $$T_{rm g}$$ was estimated to be 411 K. Bacterial inactive-active transition was discussed according to the glass transition behavior.

Journal Articles

Precise determination of $$^{12}_{Lambda}$$C level structure by $$gamma$$-ray spectroscopy

Hosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

 Times Cited Count:14 Percentile:66.75(Physics, Multidisciplinary)

Level structure of the $$^{12}_{Lambda}$$C hypernucleus was precisely determined by means of $$gamma$$-ray spectroscopy. We identified four $$gamma$$-ray transitions via the $$^{12}$$C$$(pi^{+},K^{+}gamma)$$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $$(2^{-}, 1^{-}_{1})$$ was measured to be $$161.5pm0.3$$(stat)$$pm0.3$$ (syst)keV from the direct $$M1$$ transition. Excitation energies of the $$1^{-}_{2}$$ and $$1^{-}_{3}$$ states were measured to be $$2832pm3pm4$$, keV and $$6050pm8pm7$$, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $$Lambda$$ hypernuclei.

Journal Articles

Proton irradiation effects on tensile and bend-fatigue properties of welded F82H specimens

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Endo, Shinya; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 398(1-3), p.49 - 58, 2010/03

 Times Cited Count:6 Percentile:40.42(Materials Science, Multidisciplinary)

In several institutes, R&D for an ADS have been progressed. Ferritic / martensitic (F/M) steels are the candidate material for the beam window. To obtain the irradiation data, the PIE work of the SINQ target irradiation program (STIP) specimens was carried out at JAEA. In this study, the results of PIE on F/M steel F82H and its welded joint will be reported. The results of tensile tests indicate that the irradiation hardening occurred with increasing dpa up to 10.1 dpa below 320$$^{circ}$$C irradiation. At higher dose (- 11.8 dpa) and higher temperature (- 380$$^{circ}$$C), irradiation hardening and degradation of ductility relaxed. In this study, all specimens kept its ductility after irradiation and fractured in ductile manner. The fatigue life of F82H base metal is almost the same as that of unirradiated specimens. Though the number of specimen is limited, the fatigue life of F82H EB welded joints seems to increase after irradiation. The fracture surfaces of the specimens showed transgranular morphology. While F82H TIG welded specimens were not fractured by 10$$^{7}$$ cycles.

Journal Articles

Tensile properties of austenitic stainless steels irradiated at SINQ target 3

Saito, Shigeru; Kikuchi, Kenji; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 343(1-3), p.253 - 261, 2005/08

 Times Cited Count:9 Percentile:53.26(Materials Science, Multidisciplinary)

A beam window of a spallation target will be subjected to proton/neutron irradiation, pressure wave and thermal stresses accompanied by high-energy proton beam injection. To obtain the irradiation data, the SINQ target irradiation program (STIP) was initiated in 1996 at Paul Scherrer Institute (PSI) and has been progressing. JAERI takes part in STIP and shares the PIE work. In this study, the results of tensile tests on austenitic stainless steels, JPCA and 316F SS, will be reported. The results indicate that the irradiation causes considerable hardening and degradation of ductility. The YS increases in this study are slightly large in comparison with those irradiated at fission reactor. Strain-to-necking (STN) values show sufficient large ductility of the irradiated JPCA-SA and 316F-SA. The trends of the STN decrease in this study are slightly abrupt in comparison with those irradiated at fission reactor. All specimens, including irradiated at embrittlement temperature for austenitic steels, fractured in ductile manner.

Journal Articles

Bend-fatigue properties of 590 MeV proton irradiated JPCA and 316F SS

Saito, Shigeru; Kikuchi, Kenji; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 329-333(Part1), p.1093 - 1097, 2004/08

 Times Cited Count:6 Percentile:40.81(Materials Science, Multidisciplinary)

In several institutes, research and development for an accelerator-driven spallation neutron source have been progressed. A beam window of a target will be subjected to proton/neutron irradiation, pressure wave and thermal stresses accompanied by high-energy proton beam injection. To obtain the irradiation data, the SINQ target irradiation program (STIP) at Paul Scherrer Institute (PSI) has been progressing. JAERI takes part in STIP and shares the PIE work. The STIP specimens are very small so that we developed a new fatigue-testing machine with ceramic piezoelectric actuator. The results showed that the numbers of cycles to failure (Nf) on the irradiated specimens were less than that of unirradiated specimens. Dpa dependence of Nf was not clearly seen in the irradiation conditions. On the other hand, fracture surface varied with irradiation conditions. Specimens irradiated at low temperature fractured in ductile manner. However, interglanular fractured surface was observed for 316F SS irradiated up to 12.5 dpa at 360$$^{circ}$$C.

JAEA Reports

Shielding benchmark tests of JENDL-3

Kawai, Masayoshi*; ; *; Yamano, Naoki*; *; *; *; *; Sakurai, Kiyoshi

JAERI 1330, 129 Pages, 1994/03

JAERI-1330.pdf:5.52MB

no abstracts in English

JAEA Reports

Fusion neutron shielding benchmark problems

*; Sasamoto, Nobuo; Mori, Seiji*; *; Kawai, Masayoshi*; *; Sakurai, Kiyoshi; Shin, Kazuo*; Sekimoto, Hiroshi*; Oyama, Yukio; et al.

JAERI-M 87-203, 230 Pages, 1987/12

JAERI-M-87-203.pdf:4.46MB

no abstracts in English

JAEA Reports

The Design research and development of JT-60 neutral beam injector

Kuriyama, Masaaki; Akiba, Masato; ; Araki, Masanori; Dairaku, Masayuki; ; Horiike, Hiroshi; Ito, Takao; Inoue, Takashi; Kawai, Mikito; et al.

JAERI-M 87-169, 182 Pages, 1987/10

JAERI-M-87-169.pdf:5.53MB

no abstracts in English

Journal Articles

The JT-60 neutral beam injection system

Matsuda, Shinzaburo; Akiba, Masato; Araki, Masanori; Dairaku, Masayuki; ; Horiike, Hiroshi; Ito, Takao; *; Kawai, Mikito; Komata, Masao; et al.

Fusion Engineering and Design, 5, p.85 - 100, 1987/00

 Times Cited Count:23 Percentile:87.82(Nuclear Science & Technology)

no abstracts in English

Oral presentation

Effects of the exposure of extreme environments on the life-time and breeding ability of tardigrade ${it Ramazzottius varieornatus}$

Wadachi, Hiroki*; Kunieda, Takekazu*; Sakashita, Tetsuya; Kawai, Kiyoshi*; Iwata, Kenichi*; Nakahara, Yuichi*; Hamada, Nobuyuki*; Koseki, Shigenobu*; Yamamoto, Kazutaka*; Kobayashi, Yasuhiko; et al.

no journal, , 

We studied the effects of the exposure of extreme environments on life-time and breeding ability of tardigrade ${it R. varieornatus}$ to reveal the possibility of multi-cellular organism existences in the outerspace. A life time of animals is the shortest in the heavy-ion exposed animals than any other stressors. There were significant decrease in the number of egg-laying and hatching rate between irradiated and non-irradiated animals. However, we found the next generation in all experimental conditions. Our findings suggest that tardigrades exposed to even any extreme environments could have a descendant.

Oral presentation

The Tardigrade ${it Ramazzottius varieornatus}$; A Model for astrobiological studies

Horikawa, Daiki*; Kunieda, Takekazu*; Abe, Wataru*; Koshikawa, Shigeyuki*; Nakahara, Yuichi*; Watanabe, Masahiko*; Iwata, Kenichi*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Higashi, Seigo*; et al.

no journal, , 

We report the first successful rearing of the herbivorous tardigrade, ${it Ramazzottius varieornatus}$, by supplying a green alga ${it Chlorella vulgaris}$ as a food. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle, from eggs, to juveniles, and to adults. Reared adults, while in an anhydrobiotic state, were tolerant to temperatures -196$$^{circ}$$C and 100$$^{circ}$$C. Furthermore, they were shown to be tolerant to the exposure to 99.8% acetonitrile, 1 GPa of hydrostatic pressure, or 5000 Gy of He ion radiation. We will report the details of these results, along with the description of their life history. Due to the observed tolerance to such extreme environmental conditions, we propose R. varieornatus to be included as a suitable model for astrobiological studies of multicellular organisms.

Oral presentation

Proton irradiation effects on tennsile and bend-fatigue properties of welded F82H specimens

Saito, Shigeru; Kikuchi, Kenji; Hamaguchi, Dai; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Endo, Shinya; Kawai, Masayoshi*; Yong, D.*

no journal, , 

In several institutes, research and development for an accelerator-driven transmutation system have been progressed. Ferritic/martensitic steels are the candidate material for the beam window. To obtain the irradiation data, the PIE work of the SINQ target irradiation program (STIP) specimens was carried out at JAEA. In this study, the results of PIE on F82H and its welded joint will be reported. The tensile tests were performed for F82H EB and TIG welded specimens. The results indicate that all specimens kept its ductility after 10 dpa irradiation and fractured in ductile manner. The fatigue life of F82H base metal is almost the same as that of unirradiated specimens. Though the number of specimen is limited, the fatigue life of F82H EB (15mm and 3.3mm) welded joints seems to increase after irradiation. The fracture surfaces of the specimens showed transgranular morphology. While F82H TIG welded specimens were not fractured by 10$$^{7}$$ cycles.

Oral presentation

Structure analysis of frozen sugar solution using spin-contrast-variation neutron small-angle scattering

Kumada, Takayuki; Nakagawa, Hiroshi; Sekine, Yurina; Motokawa, Ryuhei; Kawai, Kiyoshi*

no journal, , 

We succeeded in observing spin-contrast-variation neutron small-angle scattering (SCV-SANS) signal from planar nano-ice crystals generated in rapidly frozen sugar solutions.

Oral presentation

Nano-ice crystals in rapidly cooled sugar solutions observed by spin-contrast-variation small-angle neutron scattering

Kumada, Takayuki; Nakagawa, Hiroshi; Miura, Daisuke*; Sekine, Yurina; Motokawa, Ryuhei; Hiroi, Kosuke; Inamura, Yasuhiro; Oku, Takayuki; Oishi, Kazuki*; Morikawa, Toshiaki*; et al.

no journal, , 

The structure of nano-ice crystals in rapidly frozen sugar solution was elucidated by using spin-contrast-variation small-angle neutron scattering, which distinguishes the nano-ice crystal signal from the frozen amorphous solution signal by the polarization-dependent neutron scattering. The analysis revealed that the nano-ice crystals form a planar structure with a diameter exceeding tens of nanometers and a thickness of 1 nm, which is close to the critical nucleation size. This result suggests that the sugar molecules are preferentially bound to a specific face of nano-ice crystals, and then block the crystal growth perpendicular to that face.

16 (Records 1-16 displayed on this page)
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