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Journal Articles

Thick target neutron yields from 100- and 230-MeV/nucleon helium ions bombarding water, PMMA, and iron

Tsai, P.-E.; Heilbronn, L. H.*; Lai, B.-L.*; Iwata, Yoshiyuki*; Murakami, Takeshi*; Sheu, R.-J.*

Nuclear Instruments and Methods in Physics Research B, 449, p.62 - 70, 2019/06

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

The secondary neutrons produced from 100- and 230-MeV/nucleon He ions, respectively, stopping in the thick iron, PMMA and water targets are measured by the time of flight method combined with the pulse shape discrimination of liquid scintillators. The experimental data show that the secondary neutrons were contributed from breakup of projectiles, emission from overlap regions of projectile nuclei and target nuclei, and evaporation of projectiles and target nuclei. The measured double-differential thick target neutron yields, angular distributions, and total neutron yields per ion, were benchmarked by the PHITS, FLUKA, and MCNP model calculations. The default models in these codes agree the experimental data well at intermediate-to-large angles in the low-to-intermediate energy range. However, the physics models implemented in PHITS need further improvement for some particular nuclear interaction mechanisms, and this work can be an importance reference for future model development.

JAEA Reports

Confirmation tests for Warm Pre-stress (WPS) effect in reactor pressure vessel steel (Contract research)

Chimi, Yasuhiro; Iwata, Keiko; Tobita, Toru; Otsu, Takuyo; Takamizawa, Hisashi; Yoshimoto, Kentaro*; Murakami, Takeshi*; Hanawa, Satoshi; Nishiyama, Yutaka

JAEA-Research 2017-018, 122 Pages, 2018/03


Warm pre-stress (WPS) effect is a phenomenon that after applying a load at a high temperature fracture does not occur in unloading during cooling, and then the fracture toughness in reloading at a lower temperature increases effectively. Engineering evaluation models to predict an apparent fracture toughness in reloading are established using experimental data with linear elasticity. However, there is a lack of data on the WPS effect for the effects of specimen size and surface crack in elastic-plastic regime. In this study, fracture toughness tests were performed after applying load-temperature histories which simulate pressurized thermal shock transients to confirm the WPS effect. The experimental results of an apparent fracture toughness tend to be lower than the predictive results using the engineering evaluation models in the case of a high degree of plastic deformation in preloading. Considering the plastic component of preloading can refine the engineering evaluation models.

Journal Articles

Genetic changes in progeny of bystander human fibroblasts after microbeam irradiation with X-rays, protons or carbon ions; The Relevance to cancer risk

Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*

International Journal of Radiation Biology, 91(1), p.62 - 70, 2015/01

 Times Cited Count:19 Percentile:6.49(Biology)

Radiation-induced bystander effects have important implications in radiotherapy. Their persistence in normal cells may contribute to risk of health hazards, including cancer. This study investigates the role of radiation quality and gap junction intercellular communication (GJIC) in the propagation of harmful effects in progeny of bystander cells. Confluent human skin fibroblasts were exposed to microbeam radiations with different linear energy transfer (LET) by which 0.036$$sim$$0.4% of the cells were directly targeted by radiation. Following 20 population doublings, the cells were harvested and assayed for micronucleus formation, gene mutation and protein oxidation. The results showed that expression of stressful effects in the progeny of bystander cells is dependent on LET.

Journal Articles

Electrically insulated MLI and thermal anchor

Kamiya, Koji; Furukawa, Masato; Hatakenaka, Ryuta*; Miyakita, Takeshi*; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Koide, Yoshihiko; Yoshida, Kiyoshi

AIP Conference Proceedings 1573, p.455 - 462, 2014/01

 Times Cited Count:4 Percentile:11.03

The thermal shield of JT-60SA is kept at 80 K and will use the Multi Layered Insulator (MLI) to reduce radiation heat load to the superconducting coils at 4.4 K from the cryostat at 300 K. Due to plasma pulse operation, the MLI is affected by eddy current in toroidal direction. The MLI is designed to suppress the current by electrically insulating every 20 degree in the toroidal direction by covering the MLI with polyimide films. In this paper, two kinds of designs for insulated MLI are proposed focusing on a way to overlap MLI. A boil-off calorimeter method and temperature measurement has been performed to determine the thermal performance of MLI. The design of electrical insulated thermal anchor between the toroidal field (TF) coil and the thermal shield is also explained.

Journal Articles

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures; The Impact of radiation quality

Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.

Radiation Research, 180(4), p.367 - 375, 2013/10

 Times Cited Count:46 Percentile:8.61(Biology)

We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.

Journal Articles

Visualization of $$gamma$$H2AX foci caused by heavy ion particle traversal; Distribution between core track versus non-track damage

Nakajima, Nakako*; Brunton, H.*; Watanabe, Ritsuko; Shrikhande, A.*; Hirayama, Ryoichi*; Matsufuji, Naruhiro*; Fujimori, Akira*; Murakami, Takeshi*; Okayasu, Ryuichi*; Jeggo, P.*; et al.

PLOS ONE (Internet), 8(8), p.e70107_1 - e70107_14, 2013/08

 Times Cited Count:42 Percentile:10.66(Multidisciplinary Sciences)

Heavy particle irradiation can produce complex DNA double strand breaks (DSBs) within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, can create low linear energy transfer (LET) damage distant from the track. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe ions, $$gamma$$H2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered $$gamma$$H2AX foci. We also identified simple $$gamma$$H2AX foci distant from the track. They are rapidly repaired. Clustered $$gamma$$H2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple $$gamma$$H2AX foci. However, mitotic entry was observed when $$sim$$10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle.

JAEA Reports

The International Atomic Energy Agency Nuclear Energy Management School 2012

Ohgama, Kazuya; Ando, Yoko; Yamaguchi, Mika; Ikuta, Yuko; Shinohara, Nobuo; Murakami, Hiroyuki; Yamashita, Kiyonobu; Uesaka, Mitsuru*; Demachi, Kazuyuki*; Komiyama, Ryoichi*; et al.

JAEA-Review 2013-004, 76 Pages, 2013/05


JAEA together with the Japan Nuclear Human Resource Development Network (JN-HRD Net), the University of Tokyo (UT) and the Japan Atomic Industrial Forum (JAIF) cohosted the IAEA-Nuclear Energy Management School in Tokai Village, aiming that Japan will be the center of nuclear HRD in the Asian region. In the school, not only lectures by IAEA experts, but also lectures by Japanese experts and technical visits were included for foreign participants. The school contributed to the internationalization of Japanese young professionals, development of nuclear human resource of other countries, and enhancement of cooperation between IAEA and Japan. Additionally, collaborative relationship within JN-HRD Net was strengthened by the school. In this report, findings obtained during the preparatory work and the school period are reported for future international nuclear HRD activities in Japan.

Journal Articles

Effects of irradiation-particle energy on critical current density in Co-doped BaFe$$_{2}$$As$$_{2}$$

Taen, Toshihiro*; Yagyuda, Hidenori*; Nakajima, Yasuyuki*; Tamegai, Tsuyoshi*; Okayasu, Satoru; Kitamura, Hisashi*; Murakami, Takeshi*; Laviano, F.*; Ghigo, G.*

Physica C, 484, p.62 - 65, 2013/01

 Times Cited Count:8 Percentile:55.83(Physics, Applied)

We report effects of particle energy on physical properties of Co-doped BaFe$$_{2}$$As$$_{2}$$ in the case of Xe and Au irradiations. The irradiation-induced suppression of $$T$$$$_{rm c}$$ is found to be related with several factors, such as defect structures and the thickness of the crystal. Heavy-ion irradiation induces enhancement of critical current density $$J$$$$_{rm c}$$, and a weak dip in the hysteresis loop. The fish-tail effect is completely suppressed by a modest density of defects. The enhancement of $$J$$$$_{rm c}$$ is closely related to the defect structure. Namely, splayed structure in columnar defects, inevitably introduced at lower energies, results in a strong enhancement of $$J$$$$_{rm c}$$ by forced entanglement of vortices.

Journal Articles

Effects of particle irradiations on vortex states in iron-based superconductors

Tamegai, Tsuyoshi*; Taen, Toshihiro*; Yagyuda, Hidenori*; Tsuchiya, Yuji*; Mohan, S.*; Taniguchi, Tomotaka*; Nakajima, Yasuyuki*; Okayasu, Satoru; Sasase, Masato*; Kitamura, Hisashi*; et al.

Superconductor Science and Technology, 25(8), p.084008_1 - 084008_14, 2012/08

 Times Cited Count:68 Percentile:6.33(Physics, Applied)

Various kinds of energetic particles are irradiated into iron-based superconductors, and their effects on the critical current density $$J$$$$_{rm c}$$ and vortex dynamics have been systematically studied. It is found that $$J$$$$_{rm c}$$ is enhanced and vortex dynamics is strongly suppressed by energetic particles having a sufficient energy deposition rate, similar to the case of high temperature cuprate superconductors. The enhancement of $$J$$$$_{rm c}$$, in general, persists up to much higher irradiation doses than in cuprates. However, details of the effect of irradiation depend on the kind of ion species and their energies. Even with the same ions and energies, the effect is not universal for different kinds of iron-based superconductors. The correlated nature of defects created by heavy-ion irradiation is confirmed by the angular dependence of irreversible magnetization.

Journal Articles

Mechanism of radiation-induced reactions in aqueous solution of coumarin-3-carboxylic acid; Effects of concentration, gas and additive on fluorescent product yield

Yamashita, Shinichi; Baldacchino, G.*; Maeyama, Takuya*; Taguchi, Mitsumasa; Muroya, Yusa*; Lin, M.*; Kimura, Atsushi; Murakami, Takeshi*; Katsumura, Yosuke

Free Radical Research, 46(7), p.861 - 871, 2012/07

 Times Cited Count:15 Percentile:53.87(Biochemistry & Molecular Biology)

Radiation-induced reactions in aqueous solutions of a water-soluble coumarin derivative, coumarin-3-carboxyl acid (C3CA), have been investigated by pulse radiolysis with 35-MeV electron beam, final product analysis after $$^{60}$$Co $${gamma}$$-irradiations, and deterministic model simulations. It was found that C3CA reacts with the hydroxyl radical ($$^{bullet}$$OH) as well as the hydrated electron at nearly diffusion-controlled rate constants: 6.8$${times}$$10$$^{9}$$ and 2.1$${times}$$10$$^{10}$$ M$$^{-1}$$s$$^{-1}$$, respectively. Reactivity of C3CA toward O$$_{2}$$$$^{-}$$$$^{bullet}$$ was not confirmed. Production of a fluorescent molecule 7-hydroxy-coumarin-3-carboxylic acid (7OH-C3CA) was detected by a fluorescence spectrometer coupled with high performance liquid chromatography. Production yields of 7OH-C3CA were in a range from 0.025 to 0.18 (100 eV)$$^{-1}$$, depending on irradiation conditions. A variety of the yield with saturating gas, additive, and C3CA concentration implied that there are at least two pathways from scavenging reaction of C3CA toward $$^{bullet}$$OH to 7OH-C3CA: peroxidation reaction followed by elimination of perhydroxyl radical and disproportionation reaction. A reaction mechanism involving the two pathways was proposed and incorporated into the simulations, showing good explanation of experimentally measured 7OH-C3CA yields with a constant conversion factor from $$^{bullet}$$OH scavenging to 7OH-C3CA production, 4.7%, unless $${t}$$-BuOH is not added.

Journal Articles

Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution, 2; Effects of nuclear fragmentation and its simulation with PHITS

Maeyama, Takuya*; Yamashita, Shinichi; Taguchi, Mitsumasa; Baldacchino, G.*; Sihver, L.*; Murakami, Takeshi*; Katsumura, Yosuke

Radiation Physics and Chemistry, 80(12), p.1352 - 1357, 2011/12

 Times Cited Count:11 Percentile:31.31(Chemistry, Physical)

Coumari-3-carboxylic acid scavenges OH radical produced in water radiolysis, leading to production of a fluorescence probe at almost constant ratio relative to the amount of the scavenged OH radicals. This was applied in estimation of OH radical yield in water radiolysis especially with therapeutic heavy ions of GeV-class energies, i.e. $$^{12}$$C$$^{6+}$$ beams of 135, 290 and 400 MeV/u. OH yields upstream of the Bragg peaks decreased with increasing penetration depth of the projectile ions while that downstream suddenly jumped up to near the value for low-LET radiations such as $$gamma$$-rays. This is due to low-LET secondary fragmentation ions produced during long trajectory of the primary projectile C ion. Quantitative explanation by nuclear fragmentation simulations with PHITS code was attempted and resulted in 15-45% underestimation in the region behind the Bragg peaks, which would be due to the difference in geometries between irradiations of the sample solutions and dosimetry with a small ionization chamber.

Journal Articles

Development of function-graded proton exchange membrane for PEFC using heavy ion beam irradiation

Shiraki, Fumiya*; Yoshikawa, Taeko*; Oshima, Akihiro*; Oshima, Yuji*; Takasawa, Yuya*; Fukutake, Naoyuki*; Oyama, Tomoko*; Urakawa, Tatsuya*; Fujita, Hajime*; Takahashi, Tomohiro*; et al.

Nuclear Instruments and Methods in Physics Research B, 269(15), p.1777 - 1781, 2011/08

 Times Cited Count:7 Percentile:43.84(Instruments & Instrumentation)

The graded energy deposition of heavy ion beam irradiation to polymeric materials was utilized to synthesize a novel proton exchange membrane (PEM) with the graded density of sulfonic acid groups toward the thickness direction. Stacked Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were irradiated by Xe$$^{54+}$$ ion beam with the energy of 6 MeV/u under a vacuum condition. Irradiated films were grafted with styrene monomer and then sulfonated. The membrane electrode assembly (MEA) fabricated by the function graded PEM showed improved fuel cell performance in terms of voltage stability. It was expected that the function-graded PEM could control the graded concentration of sulfonic acid groups in PEM.

Journal Articles

Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution, 1; Beam quality and concentration dependences

Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*; Katsumura, Yosuke

Radiation Physics and Chemistry, 80(4), p.535 - 539, 2011/04

 Times Cited Count:23 Percentile:10.3(Chemistry, Physical)

Aqueous coumarin-3-carboxylic Acid (3CCA) solutions were irradiated with eight different ion beams covering LET range from 0.5 to above 2000 eV/nm. $$G$$-values of 7OH-3CCA, one of hydroxylated products in radiolysis of the solutions, have been determined by fluorescence-HPLC technique in 3CCA concentration range from 0.1 to 26 mM. The formation yield of 7OH-3CCA increased with increasing concentration of 3CCA while it decreased with increasing LET value of ion beam. Compared with our previous reports on $$G$$($$^{bullet}$$OH) at a scavenging capacity of 10$$^{7}$$ s with absorption spectroscopy, it was found that $$G$$(7OH-3CCA) is about (4.7$$pm$$0.6)% of $$G$$($$^{bullet}$$OH), which is consistent for all of the ion beams used in the present study. However, 7OH-3CCA yields in high CCA concentration region, especially by using extremely high LET ions, were much higher than expected values based on the above conversion factor and $$G$$($$^{bullet}$$OH) value predicted in theoretical work.

Journal Articles

Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)

Gowa, Tomoko*; Shiotsu, Tomoyuki*; Urakawa, Tatsuya*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Hama, Yoshimasa*; Washio, Masakazu*

Radiation Physics and Chemistry, 80(2), p.264 - 267, 2011/02

 Times Cited Count:6 Percentile:48.94(Chemistry, Physical)

High linear energy transfer (LET) heavy ion beams were irradiated to poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth was precisely evaluated by analyzing each one of the films of the irradiation samples which were made of stacked ETFE films. It was indicated that conjugated double bonds would be generated by heavy ion beam irradiation, and their amounts should show the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for irradiation samples in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.

Journal Articles

Changes to the chemical structure of isotactic-polypropylene induced by ion-beam irradiation

Oka, Toshitaka; Oshima, Akihiro*; Motohashi, Ryota*; Seto, Naoto*; Watanabe, Yuji*; Kobayashi, Ryoji*; Saito, Koki*; Kudo, Hisaaki*; Murakami, Takeshi*; Washio, Masakazu*; et al.

Radiation Physics and Chemistry, 80(2), p.278 - 280, 2011/02

 Times Cited Count:6 Percentile:48.94(Chemistry, Physical)

The chemical structures of various ion-beam irradiated isotactic-polypropylene samples were studied. Results of micro-Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy suggest not only the linear energy transfer, but also the fluence is effective in local transformation of the isotactic-polypropylene.

Journal Articles

Low-field anomaly of vortex dynamics in iron-pnictide superconductors

Tamegai, Tsuyoshi*; Taen, Toshihiro*; Yagyuda, Hidenori*; Nakajima, Yasuyuki*; Okayasu, Satoru; Sasase, Masato*; Kitamura, Hisashi*; Murakami, Takeshi*; Kambara, Tadashi*; Kanai, Yasuyuki*

Physica C, 471, p.777 - 780, 2011/00

 Times Cited Count:6 Percentile:66.74(Physics, Applied)

Magnetic relaxations in Ba(Fe$$_{1-x}$$Co$$_{x}$$)$$_{2}$$As$$_{2}$$ before and after swift particle irradiations are measured. The normalized relaxation rate S shows a clear suppression in a pristine sample at low fields below the self-field. Heavy-ion irradiations suppress these anomalies considerably, although there still remain weak features depending on ion species and/or energies. In a proton irradiated sample, the low-field anomaly of S survives although it is smeared compared with that in a pristine sample. All these results indicate that the low-field anomaly of S is suppressed by defects, and correlated defects have stronger effects.

Journal Articles

Critical current densities and flux creep rate in Co-doped BaFe$$_{2}$$As$$_{2}$$ with columnar defects introduced by heavy-Ion irradiation

Nakajima, Yasuyuki*; Tsuchiya, Yuji*; Taen, Toshihiro*; Yagyuda, Hidenori*; Tamegai, Tsuyoshi*; Okayasu, Satoru; Sasase, Masato*; Kitamura, Hisashi*; Murakami, Takeshi*

Physica C, 470(20), p.1103 - 1105, 2010/11

 Times Cited Count:3 Percentile:80.42(Physics, Applied)

We report the formation of columnar defects in Co-doped BaFe$$_{2}$$As$$_{2}$$ single crystals with different heavy ion irradiations. The formation of columnar defects by 200 MeV Au ion irradiation is confirmed by transmission electron microscopy and their density is about 40% of the irradiation dose. Magneto-optical imaging and bulk magnetization measurements reveal that the critical current density $$J$$$$_{rm c}$$ is enhanced in the 200 MeV Au and 800 MeV Xe ion irradiated samples while $$J$$$$_{rm c}$$ is unchanged in the 200 MeV Ni ion irradiated sample. We also find that vortex creep rates are strongly suppressed by the columnar defects. We compare the effect of heavy-ion irradiation into Co-doped BaFe$$_{2}$$As$$_{2}$$ and cuprate superconductors.

Journal Articles

Ion beam irradiation effects on resist materials

Gowa, Tomoko*; Takahashi, Tomohiro*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*

Journal of Photopolymer Science and Technology, 23(3), p.399 - 404, 2010/08

Journal Articles

Degradation of hydroxymaleimide in 2-propanol by irradiation of energetic heavy ions, 2; N$$_{2}$$-saturated system

Nakagawa, Seiko*; Taguchi, Mitsumasa; Hirota, Koichi; Murakami, Takeshi*

Radiation Physics and Chemistry, 79(8), p.890 - 893, 2010/08

 Times Cited Count:3 Percentile:72.22(Chemistry, Physical)

Hydroxymaleimide was irradiated in N$$_{2}$$-saturated 2-propanol solutions by high-energy heavy ions over a wide range of LET values. The differential G-values of the degradation of hydroxymaleimide by irradiation with the heavier ions were lower than those of the lighter ions for the same LET value. It was opposite result obtained in the air-saturated system. The degradation efficiency was 1.5 times higher, when the dose rate was 1/10 times lower. When irradiated at an LET value lower than 8 eV/nm, the G-values converged to a value less than that obtained by $$gamma$$-irradiation.

Journal Articles

Resonant magnetic X-ray diffraction study on the successive metamagnetic transitions of TbB$$_4$$ up to 30T

Inami, Toshiya; Owada, Kenji; Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Matsumura, Takeshi*; Okuyama, Daisuke*; Murakami, Yoichi*

Journal of Physics; Conference Series, 211, p.012010_1 - 012010_6, 2010/02

 Times Cited Count:3 Percentile:20.52

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