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Journal Articles

Dissolution behavior of U$$_{3}$$O$$_{8}$$, FeUO$$_{4}$$, and UO$$_{2}$$-Zr-stainless steel system samples generated in an oxidative atmosphere in the presence of malonic acid

Tonna, Ryutaro*; Sasaki, Takayuki*; Okamoto, Yoshihiro; Kobayashi, Taishi*

Journal of Nuclear Materials, 605, p.155561_1 - 155561_9, 2025/02

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

Journal Articles

$$^{149}$$Sm synchrotron-radiation-based M$"{o}$ssbauer spectroscopy of Sm-based heavy fermion compounds

Tsutsui, Satoshi; Higashinaka, Ryuji*; Mizumaki, Masaichiro*; Kobayashi, Yoshio*; Nakamura, Jin*; Ito, Takashi; Yoda, Yoshitaka*; Matsuda, Tatsuma*; Aoki, Yuji*; Sato, Hideyuki*

Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12

Journal Articles

Pulsed muon facility of J-PARC MUSE

Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Sunagawa, Hikaru*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Fujihara, Masayoshi; Tampo, Motonobu*; Kawamura, Naritoshi*; et al.

Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12

Journal Articles

Dissolution behavior of calcium uranate under oxidizing and reducing conditions

Kato, Yuto*; Sasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Okamoto, Yoshihiro

Applied Geochemistry, 175, p.106196_1 - 106196_9, 2024/11

 Times Cited Count:1 Percentile:0.00(Geochemistry & Geophysics)

Journal Articles

Self-learning path integral hybrid Monte Carlo with mixed ${it ab initio}$ and machine learning potentials for modeling nuclear quantum effects in water

Thomsen, B.; Nagai, Yuki*; Kobayashi, Keita; Hamada, Ikutaro*; Shiga, Motoyuki

Journal of Chemical Physics, 161(20), p.204109_1 - 204109_18, 2024/11

 Times Cited Count:1 Percentile:42.16(Chemistry, Physical)

We introduce the self-learning path integral hybrid Monte Carlo with mixed ${it ab initio}$ and machine learning potentials (SL-PIHMC-MIX) method which allows the application of hybrid Monte Carlo for both path integrals and for larger system sizes. The method shows savings of an order of magnitude with respect to the number of ${it ab initio}$ DFT calculations needed to calculate and converge the structure of room temperature water when using SL-PIHMC-MIX over ab initio path integral molecular dynamics (PIMD).

JAEA Reports

Neutron optics design of a neutron magnetic microscope using Wolter type I supermirror

Soyama, Kazuhiko; Hayashida, Hirotoshi*; Maruyama, Ryuji; Yamazaki, Dai; Goto, Yoshiki*; Kobayashi, Yuki*; Arakawa, Shohei*; Yamamoto, Yugo*; Suba, Kenta*; Yamamura, Kazuya*

JAEA-Research 2024-006, 15 Pages, 2024/10

JAEA-Research-2024-006.pdf:1.51MB

A neutron optics design has been conducted for a neutron magnetic microscope that utilize a Wolter type I multilayer supermirror for the purpose of magnetic fields imaging in magnetic materials. Ray trace simulation was performed for a magnifying imaging optical system with a magnification rate of 12.5 times. Based on classical model of Lamor precession, depolarization due to magnetic domains was simulated, and the effect of slope errors on the Wolter mirror created by the replica method on the spatial resolution of the microscope was investigated. As a result, reference data about the shape error required to obtain spatial resolution on the order of micrometers was obtained.

Journal Articles

Dissolution of zirconium-cerium oxide solid solution in an aqueous system

Kobayashi, Taishi*; Sato, Yutaro*; Tonna, Ryutaro*; Matsumura, Daiju; Sasaki, Takayuki*; Ikeda, Atsushi

Dalton Transactions (Internet), 53(46), p.18616 - 18628, 2024/10

 Times Cited Count:0 Percentile:0.00(Chemistry, Inorganic & Nuclear)

Journal Articles

Circular polarization measurement for individual gamma rays in capture reactions with intense pulsed neutrons

Endo, Shunsuke; Abe, Ryota*; Fujioka, Hiroyuki*; Ino, Takashi*; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kawamura, Shiori*; Kimura, Atsushi; Kitaguchi, Masaaki*; Kobayashi, Ryuju*; et al.

European Physical Journal A, 60(8), p.166_1 - 166_10, 2024/08

 Times Cited Count:2 Percentile:78.45(Physics, Nuclear)

Journal Articles

Multi-modal 3D image-based simulation of hydrogen embrittlement crack initiation in Al-Zn-Mg alloy

Higa, Ryota*; Fujihara, Hiro*; Toda, Hiroyuki*; Kobayashi, Masakazu*; Ebihara, Kenichi; Takeuchi, Akihisa*

Materials Transactions, 65(8), p.899 - 906, 2024/08

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

It is indispensable to suppress hydrogen embrittlement (HE) to develop the strength of the Al-Zn-Mg alloy. Because intergranular fracture (IGF) is mainly observed when HE occurs in the alloy, we need to understand the IGF initiation to suppress HE. In the present study, we investigated the stress, strain, and H concentration, which influence the IGF initiation, in actual fractured regions by simulation of a crystal plasticity finite element method and H diffusion analysis in a 3D image-based model, which was created based on 3D polycrystalline microstructure data obtained from X-ray imaging technique. Combining the simulation and in-situ observation of the tensile test sample by X-ray CT, we examined the stress, strain, and H concentration, and discussed the IG crack initiation condition. As a result, it is revealed that stress normal to grain boundary induced by crystal plasticity dominates IG crack initiation while the accumulation of H due to stress has little impact on it.

Journal Articles

Hydrogen bond symmetrisation in D$$_2$$O ice observed by neutron diffraction

Komatsu, Kazuki*; Hattori, Takanori; Klotz, S.*; Machida, Shinichi*; Yamashita, Keishiro*; Ito, Hayate*; Kobayashi, Hiroki*; Irifune, Tetsuo*; Shimmei, Toru*; Sano, Asami; et al.

Nature Communications (Internet), 15, p.5100_1 - 5100_7, 2024/06

 Times Cited Count:4 Percentile:72.77(Multidisciplinary Sciences)

Hydrogen bond symmetrisation is the phenomenon where a hydrogen atom is located at the centre of a hydrogen bond. Theoretical studies predict that hydrogen bonds in ice VII eventually undergo symmetrisation upon increasing pressure, involving nuclear quantum effect with significant isotope effect and drastic changes in the elastic properties through several intermediate states with varying hydrogen distribution. Despite numerous experimental studies conducted, the location of hydrogen and hence the transition pressures reported up to date remain inconsistent. Here we report the atomic distribution of deuterium in D$$_2$$O ice using neutron diffraction above 100 GPa and observe for the first time the transition from a bimodal to a unimodal distribution of deuterium at around 80 GPa. At the transition pressure, a significant narrowing of the peak widths of 110 was also observed, attributed to the structural relaxation by the change of elastic properties.

Journal Articles

Molecular geochemistry of radium; A key to understanding cation adsorption reaction on clay minerals

Yamaguchi, Akiko; Kurihara, Yuichi*; Nagata, Kojiro*; Tanaka, Kazuya; Higaki, Shogo*; Kobayashi, Toru; Tanida, Hajime; Ohara, Yoshiyuki*; Yokoyama, Keiichi; Yaita, Tsuyoshi; et al.

Journal of Colloid and Interface Science, 661, p.317 - 332, 2024/05

 Times Cited Count:6 Percentile:72.77(Chemistry, Physical)

no abstracts in English

Journal Articles

Spin dependence in the $$p$$-wave resonance of $$^{139}$$$overrightarrow{textrm{La}}$+$overrightarrow{n}$

Okudaira, Takuya*; Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.

Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04

 Times Cited Count:2 Percentile:78.45(Physics, Nuclear)

Journal Articles

High sensitivity of a future search for effects of $$P$$-odd/$$T$$-odd interactions on the 0.75 eV $$p$$-wave resonance in $$overrightarrow{n}$$+$$^{139}overrightarrow{textrm{La}}$$ forward transmission determined using a pulsed neutron beam

Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Hirota, Katsuya*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.

Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04

 Times Cited Count:1 Percentile:23.17(Physics, Nuclear)

Journal Articles

Atomic position and the chemical state of an active Sn dopant for Sn-doped $$beta$$-Ga$$_{2}$$O$$_{3}$$(001)

Tsai, Y. H.*; Kobata, Masaaki; Fukuda, Tatsuo; Tanida, Hajime; Kobayashi, Toru; Yamashita, Yoshiyuki*

Applied Physics Letters, 124(11), p.112105_1 - 112105_5, 2024/03

 Times Cited Count:2 Percentile:62.71(Physics, Applied)

Journal Articles

Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloy through multi-modal 3D image-based simulation

Fujihara, Hiro*; Toda, Hiroyuki*; Ebihara, Kenichi; Kobayashi, Masakazu*; Mayama, Tsuyoshi*; Hirayama, Kyosuke*; Shimizu, Kazuyuki*; Takeuchi, Akihisa*; Uesugi, Masayuki*

International Journal of Plasticity, 174, p.103897_1 - 103897_22, 2024/03

 Times Cited Count:8 Percentile:94.71(Engineering, Mechanical)

Hydrogen(H) embrittlement in high-strength aluminum(Al) alloys is a crucial problem. H accumulation at the interface of precipitates in Al alloy is considered to cause embrittlement. However, there is no quantitative knowledge regarding the interaction between H distribution and stress field near cracks. In this study, using a multi-modal three-dimensional image-based simulation combining the crystal plasticity finite element method and H diffusion analysis, we tried to capture the stress distribution near the crack, its influence on the H distribution, and the probability of crack initiation in the experimental condition. As a result, it was found that grain boundary cracks transition to quasi-cleavage cracks in the region where the cohesive energy of the semi-coherent interface of MgZn$$_2$$ precipitates decreases due to H accumulation near the tip. We believe the present simulation method successfully bridges nanoscale delamination and macroscale brittle fracture.

Journal Articles

Onset of collectivity for argon isotopes close to $$N=32$$

Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Duguet, T.*; G$'o$mez-Ramos, M.*; Holt, J. D.*; Hu, B. S.*; et al.

Physical Review C, 109(3), p.034312_1 - 034312_15, 2024/03

 Times Cited Count:2 Percentile:58.81(Physics, Nuclear)

no abstracts in English

Journal Articles

Dissolution behavior and aging of iron-uranium oxide

Tonna, Ryutaro*; Sasaki, Takayuki*; Okamoto, Yoshihiro; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*

Journal of Nuclear Materials, 589, p.154862_1 - 154862_10, 2024/02

 Times Cited Count:2 Percentile:46.61(Materials Science, Multidisciplinary)

The dissolution behavior of FeUO$$_{4}$$ compounds formed by a high-temperature reaction of UO$$_{2}$$ with iron, a stainless-steel component of reactor structural materials, was investigated under atmospheric conditions. The compounds were prepared in an electric furnace using U$$_{3}$$O$$_{8}$$ and Fe$$_{3}$$O$$_{4}$$ as starting materials, and their solid states were analyzed using X-ray diffraction, scanning electron microscopy energy dispersive X-ray spectroscopy, and X-ray absorption fine structure spectroscopy. The concentration of nuclides dissolved in water was examined by performing static leaching tests of FeUO$$_{4}$$ compounds for up to three months. A redox reaction was proposed to occur between trivalent Fe and pentavalent U ions in the early stage of FeUO$$_{4}$$ dissolution. It was thermodynamically deduced that the reduced divalent Fe ion was finally oxidized into a trivalent ion in the presence of dissolved oxygen, and iron hydroxide limited the solubility of Fe. Meanwhile, the concentration of hexavalent U (i.e., uranyl ion) was limited owing to the presence of secondary minerals such as metaschoepite and sodium uranate and subsequently decreased, possibly owing to sorption on Fe oxides, for example. The concentrations of multivalent ions of fission products, such as Ru and Ce, also decreased, likely for the reason above. By contrast, the concentration of soluble Cs ions did not decrease. The validity of this interpretation was supported by comparing the results with the dissolution behavior of a reference sample (Fe-free U$$_{3}$$O$$_{8}$$).

Journal Articles

Effect of Mn substitution on the electronic structure for Mn-doped indium-tin oxide films studied by soft and hard X-ray photoemission spectroscopy

Otsuki, Daiki*; Ishida, Tatsuhiro*; Tsutsumi, Naoya*; Kobayashi, Masaki*; Inagaki, Kodai*; Yoshida, Teppei*; Takeda, Yukiharu; Fujimori, Shinichi; Yasui, Akira*; Kitagawa, Saiki*; et al.

Physical Review Materials (Internet), 7(12), p.124601_1 - 124601_6, 2023/12

 Times Cited Count:2 Percentile:21.90(Materials Science, Multidisciplinary)

Journal Articles

Slightly hydrogen-ordered state of ice IV evidenced by ${it in situ}$ neutron diffraction

Kobayashi, Hiroki*; Komatsu, Kazuki*; Ito, Hayate*; Machida, Shinichi*; Hattori, Takanori; Kagi, Hiroyuki*

Journal of Physical Chemistry Letters (Internet), 14(47), p.10664 - 10669, 2023/11

 Times Cited Count:2 Percentile:28.18(Chemistry, Physical)

Ice IV is a metastable high-pressure phase of ice in which the water molecules exhibit orientational disorder. Although orientational ordering is commonly observed for other ice phases, it has not been reported for ice IV. We conducted ${it in situ}$ powder neutron diffraction experiments for DCl-doped D$$_{2}$$O ice IV to investigate hydrogen ordering in ice IV. We found abrupt changes in the temperature derivative of unit cell volume, dV/dT, at about 120 K, and revealed their slightly ordered structure at low temperatures based on the Rietveld method. The occupancy of the D1 site deviates from 0.5; it increased when samples were cooled at higher pressures and reached 0.282(5) at 2.38 GPa, 58 K. Our results evidence the presence of a low-symmetry hydrogen-ordered state corresponding to ice IV. It seems, however, difficult to experimentally access the completely ordered phase corresponding to ice IV by slow cooling at high pressure.

Journal Articles

Multi-modal 3D image-based simulation of hydrogen embrittlement crack initiation in Al-Zn-Mg alloy

Higa, Ryota*; Fujihara, Hiro*; Toda, Hiroyuki*; Kobayashi, Masakazu*; Ebihara, Kenichi; Takeuchi, Akihisa*

Keikinzoku, 73(11), p.530 - 536, 2023/11

In Al-Zn-Mg alloys, suppression of hydrogen embrittlement is necessary to improve their strength. In this study, the distribution of stress, strain, and hydrogen concentration in the actual fracture region was investigated using the crystal plasticity finite element method and hydrogen diffusion analysis based on a model derived from three-dimensional polycrystalline microstructural data obtained by X-ray CT. In addition, the distributions of stress, strain, and hydrogen concentration were compared with the actual crack initiation behavior by combining in-situ observation of tensile tests using X-ray CT and simulation. The results show that stress loading perpendicular to the grain boundary due to crystal plasticity dominates grain boundary crack initiation. It was also found that internal hydrogen accumulation due to crystal plasticity has little effect on crack initiation.

1409 (Records 1-20 displayed on this page)