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Journal Articles

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

 Times Cited Count:10 Percentile:98.7(Physics, Multidisciplinary)

A quasifree ($$p$$,$$pn$$) experiment was performed to study the structure of the Borromean nucleus $$^{17}$$B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for $$1s_{1/2}$$ and $$0d_{5/2}$$ orbitals, and a surprisingly small percentage of 9(2)% was determined for $$1s_{1/2}$$. Our finding of such a small $$1s_{1/2}$$ component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in $$^{17}$$B. The present work gives the smallest $$s$$- or $$p$$-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of $$s$$ or $$p$$ orbitals is not a prerequisite for the occurrence of a neutron halo.

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

 Times Cited Count:9 Percentile:88.96(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.

Journal Articles

Thermal fatigue test on dissimilar welded joint between Gr.91 and 304SS

Wakai, Takashi; Kobayashi, Sumio; Kato, Shoichi; Ando, Masanori; Takasho, Hideki*

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 7 Pages, 2017/07

This paper describes a thermal fatigue test on a structural model with a dissimilar welded joint. In the present design of JSFR, there may be dissimilar welded joints between ferritic and austenitic steels especially in IHX and SG. Creep-fatigue is one of the most important failure modes in JSFR components. However, the creep-fatigue damage evaluation method has not been established for dissimilar welded joint. To investigate the evaluation method, structural test will be needed for verification. Therefore, a thermal fatigue test on a thick-wall cylinder with a circumferential dissimilar welded joint between Mod.9Cr-1Mo steel and 304SS was performed. Since the coefficients of thermal expansion of these steels were significantly different, buttering layer of Ni base alloy was installed between them. After the completion of the test, deep cracks were observed at the HAZ in 304SS, as well as at HAZ in Mod.9Cr-1Mo steel. There were many tiny surface cracks in BM of 304SS. According to the fatigue damage evaluation based on the finite element analysis results, the largest fatigue damage was calculated at HAZ in 304SS. Large fatigue damage was also estimated at BM of 304SS. Fatigue cracks were observed at HAZ and BM of 304SS in the test, so that analytical results are in a good agreement with the observations. However, though relatively small fatigue damage was estimated at HAZ in Mod.9Cr-1Mo steel, deep fatigue cracks were observed in the test. To identify the cause of such a discrepancy between the test and calculations, we performed a series of finite element analyses. Some metallurgical investigations were also performed.

Journal Articles

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03

The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.

Journal Articles

Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation

Tomita, Masanori*; Matsumoto, Hideki*; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke*; Maeda, Munetoshi*; Kobayashi, Yasuhiko

Life Sciences in Space Research, 6, p.36 - 43, 2015/07

A radiation-induced bystander response is generally known as a cellular response induced in unirradiated cell by receiving bystander signaling factors released from directly irradiated cells of a cell population. Bystander responses induced by high-LET heavy ions at low fluence are an important problem concerning the health of astronauts in the space environment. Here we set out NO-mediated bystander signal transductions induced by high-LET heavy-ion microbeam irradiation in normal human fibroblasts. Our findings suggest that Akt- and NF-$$kappa$$B-dependent signaling pathway involving COX-2 plays an important role in the NO-mediated high-LET heavy-ion-induced bystander responses. Additionally, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells, which are distinguish form directly irradiated cells.

Journal Articles

Mechanisms for the induction of radioadaptive response by radiation-induced bystander response

Matsumoto, Hideki*; Tomita, Masanori*; Otsuka, Kensuke*; Hatashita, Masanori*; Maeda, Munetoshi*; Funayama, Tomoo; Yokota, Yuichiro; Suzuki, Michiyo; Sakashita, Tetsuya; Ikeda, Hiroko; et al.

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 76, 2015/03

The objective of this project is to elucidate molecular mechanisms for the induction of radioadaptive response through radiation-induced bystander responses induced by irradiation with heavy ion microbeams in JAEA. We found that the adaptive response was induced by Ar (520 MeV $$^{40}$$Ar$$^{14+}$$) microbeam-irradiation of a limited number of cells, followed by the broad beam-irradiation and that the adaptive response was almost completely suppressed by the addition of carboxy-PTIO, as a nitric oxide (NO) scavenger. In addition, we found several genes induced specifically and preferentially when radioadaptive response could be induced. We confirmed that ${it iNOS}$ expression was specifically induced only when radioadaptive response could be induced. Our findings strongly suggested that radioadaptive response can be induced by NO-mediated bystander responses evoked by irradiation with heavy ion microbeams.

Journal Articles

Analysis of bystander response in 3D cultured tissue induced by heavy-ion microbeam irradiation

Tomita, Masanori*; Matsumoto, Hideki*; Otsuka, Kensuke*; Funayama, Tomoo; Yokota, Yuichiro; Suzuki, Michiyo; Sakashita, Tetsuya; Kobayashi, Yasuhiko

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 77, 2015/03

Radiation-induced bystander responses are defined as responses in cells that have not been directly targeted by radiation but are in the neighborhood of cells that have been directly exposed. In this study, we aim to clarify a role of bystander response to sustain the homeostasis of damaged tissue using heavy-ion microbeams. We established the heavy-ion microbeam irradiation method to a 3D cultured human epidermis. Using this method, a viable cell rate of the 3D cultured human epidermis irradiated with 260 MeV $$^{20}$$Ne-ion microbeams or broadbeams was analyzed by the MTT method.

Journal Articles

Thermal transient test and strength evaluation of a tubesheet structure made of Mod.9Cr-1Mo steel, 1; Test model design and experimental results

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 275, p.408 - 421, 2014/08

AA2013-0395.pdf:2.65MB

 Times Cited Count:2 Percentile:19.81(Nuclear Science & Technology)

To clarify the failure mode of a semispherical tubesheet structure originally designed for SG in the JSFR, a cyclic thermal loading test was performed using a tubesheet model test structure. The tubesheet model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loads using a large-scale sodium loop, in which sodium heated to 600$$^{circ}$$C and 250$$^{circ}$$C was flowed repeatedly with periods for each transient of 2 and 1 h, respectively. After the test, the test model was inspected by PT. Then, observation using a SEM and hardness testing were performed. A thermal-hydraulic analysis was also performed to validate the measured temperature history during the thermal transient. Through these examinations and evaluation with thermal-hydraulic analysis, the manner of failure in the tubesheet under cyclic thermal loading is discussed.

Journal Articles

Thermal transient test and strength evaluation of a tubesheet structure made of Mod.9Cr-1Mo steel, 2; Creep-fatigue strength evaluation

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 275, p.422 - 432, 2014/08

AA2013-0396.pdf:1.44MB

 Times Cited Count:8 Percentile:60.89(Nuclear Science & Technology)

In this study, the strength of a tubesheet test model simulating a semispherical tubesheet structure subjected to cyclic thermal transients was evaluated using the finite element analysis (FEA). A test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loading using a large-scale sodium loop, in which elevated-temperature sodium at 600$$^{circ}$$C and 250$$^{circ}$$C was flowed repeatedly and kept at the final temperature for 2 and 1 h, respectively. Heat transfer analysis and stress analysis were performed using the sodium temperature data measured during the test. Then, the elastic and inelastic stress analysis results were used to investigate the failure mechanism by creep-fatigue damage and evaluate the failure strength. The evaluation based on the results of inelastic analysis estimated the number of cycles to failure within a factor of 3.

Journal Articles

Creep-fatigue evaluation of a structural model made of Mod.9Cr-1Mo steel subjected to the cyclic thermal loading

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nihon Kikai Gakkai M&M 2013 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), p.OS1510_1 - OS1510_3, 2013/10

To validate the failure mode and assess creep-fatigue damage evaluation, a thick cylinder test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of accelerated thermal transient loading using a large-scale sodium loop through which liquid sodium at 600$$^{circ}$$C and 250$$^{circ}$$C flowed repeatedly, with the period of each transient being 2 h and 1 h, respectively. After completion of the test, liquid penetrant testing, a surface observation and hardness testing were performed to characterize failure mode. Based on the finite element analysis, creep-fatigue life was evaluated by applying the JSME FRs code. The failure cycles evaluated by rules described in the JSME FRs code was shown to have a safety margin of greater than 300 times for this system.

Journal Articles

$$^{99}$$Mo-$$^{rm 99m}$$Tc production process by (n,$$gamma$$) reaction with irradiated high-density MoO$$_{3}$$ pellets

Tsuchiya, Kunihiko; Nishikata, Kaori; Tanase, Masakazu*; Shiina, Takayuki*; Ota, Akio*; Kobayashi, Masaaki*; Yamamoto, Asaki*; Morikawa, Yasumasa*; Takeuchi, Nobuhiro*; Kaminaga, Masanori; et al.

Proceedings of 6th International Symposium on Material Testing Reactors (ISMTR-6) (Internet), 9 Pages, 2013/10

no abstracts in English

Journal Articles

Thermal fatigue crack growth tests and analyses of thick wall cylinder made of Mod.9Cr-1Mo steel

Wakai, Takashi; Inoue, Osamu*; Ando, Masanori; Kobayashi, Sumio

Transactions of 22nd International Conference on Structural Mechanics in Reactor Technology (SMiRT-22) (CD-ROM), 9 Pages, 2013/08

Journal Articles

Thermal transient test and strength evaluation of a thick cylinder model made of Mod.9Cr-1Mo steel

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 255, p.296 - 309, 2013/02

 Times Cited Count:17 Percentile:83.75(Nuclear Science & Technology)

To verify the failure mode and assess creep-fatigue damage, a thick cylinder test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of accelerated thermal transient loading using a large-scale sodium loop through which liquid sodium at 600 $$^{circ}$$C and 250 $$^{circ}$$C flowed repeatedly, with the period of each transient being 2 h and 1 h, respectively. After completion of the test, the test model was inspected using liquid penetrant testing. Observations using a scanning electron microscope and hardness testing were then performed to characterize creep-fatigue damage in the structural model subjected to cyclic thermal transient loading in a sodium environment. Finite element analysis were performed to evaluate the relationship between creep-fatigue damage and the observed crack conditions.

Journal Articles

Development of $$^{99}$$Mo-$$^{rm 99m}$$Tc domestic production with high-density MoO$$_{3}$$ pellets by (n,$$gamma$$) reaction

Tsuchiya, Kunihiko; Tanase, Masakazu*; Takeuchi, Nobuhiro*; Kobayashi, Masaaki*; Hasegawa, Yoshio*; Yoshinaga, Hideo*; Kaminaga, Masanori; Ishihara, Masahiro; Kawamura, Hiroshi

Proceedings of 5th International Symposium on Material Testing Reactors (ISMTR-5) (Internet), 10 Pages, 2012/10

As one of effective uses of the JMTR, JAEA has a plan to produce $$^{99}$$Mo by (n, $$gamma$$) method, a parent nuclide of $$^{rm 99m}$$Tc. In case of Japan, the supplying of $$^{99}$$Mo depends only on imports from foreign countries. The R&D on production method of $$^{99}$$Mo -$$^{rm 99m}$$Tc has been performed with Japanese industrial users under the cooperation programs. The main R&D items for the production are (1) Fabrication of irradiation target such as the sintered MoO$$_{3}$$ pellets, (2) Separation and concentration of $$^{rm 99m}$$Tc by the solvent extraction from Mo solution, (3) Examination of $$^{rm 99m}$$Tc solution for a medicine, and (4) Mo recycling from Mo generator and solution. In this paper, the status of the R&D is introduced for the production of $$^{99}$$Mo -$$^{rm 99m}$$Tc.

Journal Articles

Electron compound nature in a surface atomic layer of a two-dimensional hexagonal lattice

Matsuda, Iwao*; Nakamura, Fumitaka*; Kubo, Keisuke*; Hirahara, Toru*; Yamazaki, Shiro*; Choi, W. H.*; Yeom, H. W.*; Narita, Hisashi*; Fukaya, Yuki; Hashimoto, Mie*; et al.

Physical Review B, 82(16), p.165330_1 - 165330_6, 2010/10

 Times Cited Count:9 Percentile:43.25(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Beam test of chopped beam loading compensation for the J-PARC linac 400-MeV upgrade

Kobayashi, Tetsuya; Ikegami, Masanori*

Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.256 - 258, 2010/09

The function of the chopped beam loading compensation was implemented into the digital feedback/feed-forward control system of the J-PARC Linac LLRF system to stabilize the ACS cavity fields for the 400-MeV upgrade. The beam test of the chopped beam loading compensation was performed with the present 324-MHz cavity system. Consequently the chopped beam loading was successfully compensated and that this system is valid.

Journal Articles

Beam test of chopped beam loading compensation for the J-PARC Linac 400-MeV upgrade

Kobayashi, Tetsuya; Ikegami, Masanori*

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.696 - 698, 2010/08

The function of the chopped beam loading compensation was implemented into the digital feedback/feed-forward control system of the J-PARC Linac LLRF system to stabilize the ACS cavity fields for the 400-MeV upgrade. The beam test of the chopped beam loading compensation was performed with the present 324-MHz cavity system. As the result, the chopped beam loading was successfully compensated and that this system is valid.

Journal Articles

Development of fast beam-stop system using RF chopper

Kikuzawa, Nobuhiro; Suzuki, Takahiro; Ito, Yuichi; Miura, Akihiko; Fukuta, Shimpei; Ikegami, Masanori*; Sako, Hiroyuki; Kobayashi, Tetsuya; Suzuki, Hiroyuki; Hasegawa, Kazuo

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.677 - 679, 2010/08

To avoid heat damage and radioactivation by beam loss of the J-PARC accelerator, Machine Protection System (MPS) has been developed. Actually, high responsibility and high reliability have been achieved in J-PARC. Beam-stop method in addition to a way of RFQ OFF has been requested in order to avoid damage to the RFQ. Therefore, we have been developing a fast beam-stop system by using a RF chopper. The fast beam-stop system, including beam test, is described in this paper.

Journal Articles

MEBT-chopper tuning procedure and its tolerance

Miura, Akihiko; Kobayashi, Tetsuya; Hasegawa, Kazuo; Sako, Hiroyuki; Ikegami, Masanori*

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.939 - 941, 2010/08

MEBT-Chopper tuning procedure was proposed using a downstream wire scanner monitor and this has been employed for the beam commissioning of the J-PARC Linac. This paper introduces the results obtained by several tuning experiences and its tendencies. Finally, tolerance depending on the tank level of RFQ (Radio-Frequency Quadrupole Linac) is introduced.

Journal Articles

Basic vacuum test of 500-kV photocathode DC gun components at KEK

Yamamoto, Masahiro*; Uchiyama, Takashi*; Miyajima, Tsukasa*; Honda, Yosuke*; Sato, Kotaro*; Matsuba, Shunya*; Saito, Yoshio*; Kobayashi, Masanori*; Kurisu, Hiriki*; Hajima, Ryoichi; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.717 - 720, 2010/08

A 500-kV photocathode DC electron gun which can supply the beam of a low emittance and a high average current has been developed in collaboration with KEK, JAEA, Hiroshima Univ., Nagoya Univ. and Yamaguchi Univ. The vacuum of the gun chamber has to be lower Extreme High Vacuum for maintain cathode-life time. A titanium chamber and new material of ceramic were employed to reduce outgassing rate. The result of outgassing rate of the gun chamber is described in this report.

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