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Ishida, Takekazu*; Vu, TheDang*; Shishido, Hiroaki*; Aizawa, Kazuya; Oku, Takayuki; Oikawa, Kenichi; Harada, Masahide; Kojima, Kenji M*; Miyajima, Shigeyuki*; Koyama, Tomio*; et al.
Journal of Low Temperature Physics, 214(3-4), p.152 - 157, 2024/02
Times Cited Count：0 Percentile：0.01(Physics, Applied)
single crystals based on Bragg-dip analysis using a delay-line superconducting sensorShishido, Hiroaki*; Vu, TheDang*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; Miyajima, Shigeyuki*; et al.
Journal of Applied Crystallography, 56(4), p.1108 - 1113, 2023/08
Times Cited Count：0 Percentile：0.02(Chemistry, Multidisciplinary)Shishido, Hiroaki*; Nishimura, Kazuma*; Vu, TheDang*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; et al.
IEEE Transactions on Applied Superconductivity, 31(9), p.2400505_1 - 2400505_5, 2021/12
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method. We obtained the neutron transmission images of a Gd-Al alloy sample, inside which single crystals of GdAl were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the 
Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 
m 
12 m. Gd selective imaging was performed using the resonance dip of Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.
Vu, TheDang; Shishido, Hiroaki*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; Miyajima, Shigeyuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 1006, p.165411_1 - 165411_8, 2021/08
Times Cited Count：1 Percentile：18.12(Instruments & Instrumentation)Vu, TheDang; Shishido, Hiroaki*; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Oku, Takayuki; Soyama, Kazuhiko; Aizawa, Kazuya; et al.
Superconductor Science and Technology, 34(1), p.015010_1 - 015010_10, 2021/01
Times Cited Count：3 Percentile：26.56(Physics, Applied)Shishido, Hiroaki*; Nishimura, Kazuma*; Vu, TheDang*; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; et al.
Journal of Physics; Conference Series, 1590, p.012033_1 - 012033_8, 2020/10
Times Cited Count：0 Percentile：0.01(Engineering, Electrical & Electronic)Vu, TheDang; Nishimura, Kazuma*; Shishido, Hiroaki*; Harada, Masahide; Oikawa, Kenichi; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; Soyama, Kazuhiko; Aizawa, Kazuya; et al.
Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07
Times Cited Count：0 Percentile：0.01(Engineering, Electrical & Electronic)
Xe ions on proton, deuteron, and carbon targetsSun, X. H.*; Wang, H.*; Otsu, Hideaki*; Sakurai, Hiroyoshi*; Ahn, D. S.*; Aikawa, Masayuki*; Fukuda, Naoki*; Isobe, Tadaaki*; Kawakami, Shunsuke*; Koyama, Shumpei*; et al.
Physical Review C, 101(6), p.064623_1 - 064623_12, 2020/06
Times Cited Count：5 Percentile：51.79(Physics, Nuclear)The spallation and fragmentation reactions of Xe induced by proton, deuteron and carbon at 168 MeV/nucleon were studied at RIKEN Radioactive Isotope Beam Factory via the inverse kinematics technique. The cross sections of the lighter products are larger in the carbon-induced reactions due to the higher total kinetic energy of carbon. The energy dependence was investigated by comparing the newly obtained data with previous results obtained at higher reaction energies. The experimental data were compared with the results of SPACS, EPAX, PHITS and DEURACS calculations. These data serve as benchmarks for the model calculations.
Iizawa, Yuki*; Shishido, Hiroaki*; Nishimura, Kazuma*; Vu, TheDang*; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; et al.
Superconductor Science and Technology, 32(12), p.125009_1 - 125009_8, 2019/12
Times Cited Count：13 Percentile：58.41(Physics, Applied)
B converterVu, TheDang; Iizawa, Yuki*; Nishimura, Kazuma*; Shishido, Hiroaki*; Kojima, Kenji*; Oikawa, Kenichi; Harada, Masahide; Miyajima, Shigeyuki*; Hidaka, Mutsuo*; Oku, Takayuki; et al.
Journal of Physics; Conference Series, 1293, p.012051_1 - 012051_9, 2019/10
Times Cited Count：5 Percentile：93.26(Materials Science, Multidisciplinary)Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：8 Percentile：55.71(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
-methyltyrosine (FAMT) uptake on PET in patients with oesophageal cancerSuzuki, Shigemasa*; Kaira, Kyoichi*; Ohshima, Yasuhiro; Ishioka, Noriko; Soda, Makoto*; Yokobori, Takehiko*; Miyazaki, Tatsuya*; Oriuchi, Noboru*; Tominaga, Hideyuki*; Kanai, Yoshikatsu*; et al.
British Journal of Cancer, 110(8), p.1985 - 1991, 2014/04
Times Cited Count：24 Percentile：60.2(Oncology)
Am content on homogenization of denatured Pu with broad range of neutron energy based on U irradiation test in the experimental fast reactor JoyoShiba, Tomooki*; Sagara, Hiroshi*; Onishi, Takashi; Koyama, Shinichi; Maeda, Shigetaka; Han, C. Y.*; Saito, Masaki*
Annals of Nuclear Energy, 51, p.74 - 80, 2013/01
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The design consideration of DU-Am oxide fuel pin was performed for Pu denaturing in the framework of the protected plutonium production based on the irradiation analyses of the depleted U (DU) samples irradiated in the environment of broad range of neutron energy in the experimental fast reactor Joyo. From the results of irradiation analyses of DU, it was confirmed that there is a strong dependence of transmutation behavior of DU on the resonance neutron ratio even in a fast reactor. Also, it was confirmed that there is a strong effect of sample material form and shape on generated Pu nuclide inventory especially near the reflector area (
20% resonance neutron ratio), because of the intensive self-shielding of 
U, though less is expected for Am. Sensitivity study of hypothetical DU-Am oxide fuel pellet irradiation on neutron energy and burn-up was performed to evaluate significant gradient of radial Pu isotopic composition profile (e.g., from 12 to 18% distribution in 3% Am doping, in 30% resonance neutron ratio and in 4.010
[n/cm
] of neutron fluence inside a large pellet with softened neutron spectrum), and vulnerability of the fuel pellet surface in terms of Pu denaturing was revealed. Design consideration of radial zoning of Am content was introduced to flatten the radial distribution of isotopic composition of Pu. The results of radial zoning of Am (4% and 3% of Am in the outer and inner zone of DU-Am oxide fuel pellet) in hypothetical irradiation neutronics analysis showed the radial profile of produced Pu is over 15 at.% of Pu isotopic composition in any zone and meets the criteria of Kimura et al. based on decay heat of Pu to impede utilization to fission explosive devices.
sp
pillar stability experiment, 1; Continuum based approaches using finite element method and comparison with other analysis modelChijimatsu, Masakazu*; Koyama, Tomofumi*; Shimizu, Hiroyuki*; Nakama, Shigeo; Fujita, Tomoo
Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.437 - 442, 2013/01
DECOVALEX-2011 is an international cooperation project for enhancing the numerical models of radioactive waste repositories. In Task B of DECOVALEX-2011 project, the failure mechanism during excavation, heating and destressing processes observed in the sp pillar stability experiment (APSE), which carried out at the sp Hard Rock Laboratory by the Swedish Nuclear Fuel and Waste Management Company (SKB), were simulated using Finite Element Method. When the calibrated parameters were used, simulation results agree qualitatively well with the experimental results. Therefore, it can be said that the spalling phenomenon is expressible even by the application with the continuum model by the use of the suitable parameters.
SP
pillar stability experiment, 2; Discontinuum based approaches using distinct element methodShimizu, Hiroyuki*; Koyama, Tomofumi*; Chijimatsu, Masakazu*; Fujita, Tomoo; Nakama, Shigeo
Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.443 - 448, 2013/01
DECOVALEX-2011 is an international cooperation project for enhancing the numerical models of radioactive waste repositories. In Task B of DECOVALEX-2011 project, the failure mechanism during excavation, heating and destressing processes observed in the sp pillar stability experiment (APSE), which carried out at the sp Hard Rock Laboratory by the Swedish Nuclear Fuel and Waste Management Company (SKB), were simulated using two dimensional Distinct Element Method. As a result, it is found that the simulated crack generation and propagation during the destressing process by 2D-DEM agree qualitatively well with the observation at site.
Shimizu, Hiroyuki*; Koyama, Tomofumi*; Chijimatsu, Masakazu*; Fujita, Tomoo; Nakama, Shigeo
Doboku Gakkai Rombunshu, A2 (Oyo Rikigaku) (Internet), 68(2), p.I_477 - I_486, 2012/00
In this paper, the coupled thermal-mechanical processes in the sp pillar stability experiments (APSE) were simulated using Distinct Element Method (DEM). By considering pre-existing cracks in the rock model, mechanical response of the rock during excavation phase and heating phase were successfully represented by DEM. Simulation results agree qualitatively well with the experimental results. However, the microcracks in the simulation were widely distributed around the heater and exfoliation of rock surfaces observed in the 
experiment was not formed accurately. To simulate more realistically the experimental results by the DEM models, the calibration of the microscopic parameters considering the model scale should be done. Moreover, more detailed discussion on the excavation damaged zone around the borehole and the distribution of pre-existing cracks are required.
O
Matsumoto, Keisuke*; Koyama, Tsukasa*; Mori, Shigeo*; Yoshii, Kenji; Kambe, Takashi*; Ikeda, Naoshi*
IOP Conference Series; Materials Science and Engineering, 18(9), p.092047_1 - 092047_4, 2011/09
Times Cited Count：1 Percentile：52.59(Materials Science, Ceramics)Changes of charge ordered (CO) structure by partial substitution of Mn for Fe in YbFeO were investigated by a transmission electron microscope (TEM), incombination with conventional dielectric measurement. It is revealed that partial substitution of Mn
for Fe in YbFeO destroyed drastically the CO structure with the wave vector of q=
1/3 1/3 1/2. Consequently polar clustering structure giving rise to honeycomb-shaped diffuse streaks was found in YbFeMnO. The random distribution of polar clustering structure gives rise to characteristic broad dielectric dispersion.
Shimizu, Hiroyuki*; Koyama, Tomofumi*; Murata, Sumihiko*; Ishida, Tsuyoshi*; Chijimatsu, Masakazu*; Fujita, Tomoo; Nakama, Shigeo
International Journal of the JCRM (Internet), 7(1), p.33 - 36, 2011/09
In this research, newly developed numerical approaches using the Distinct Element Method (DEM) were presented, and a series of DEM simulations were performed for better understanding the physical phenomena and mechanism for the following two fundamental issues in rock engineering field. The first issue is the Class II behavior of the brittle rocks under uniaxial compression. The radial strain control method for uniaxial compression tests was introduced in the DEM codes and the Class II behavior of rocks was simulated. The simulation results suggest that the DEM can reproduce the Class II behavior of the rock successfully and revealed that the loading condition of rocks will play an important role for the Class II behavior. The second issue is the hydraulic fracturing behavior in rocks. A series of simulations for hydraulic fracturing in rock was performed by using the flow-coupled DEM code. Simulation results clearly show that the fluid infiltration behavior depends on the fluid viscosity. The fluid infiltrates into the fracture immediately, when a low viscosity fluid is used and the fluid infiltrates slowly into the cracks after the fracture generation and propagation, when a high viscosity fluid is used. Moreover, the tensile cracks are dominantly generated in the DEM simulations as expected in the conventional theory. However, the energy released from tensile cracks becomes smaller due to the fact that the tensile strength of rock is usually smaller than the compressive one. Such a small AE events is not distinguishable from noise and hard to recognize during laboratory experiments. Therefore, in AE measurements, shear type AE events with large energy are dominantly observed.
OMatsumoto, Keisuke*; Koyama, Tsukasa*; Mori, Shigeo*; Yoshii, Kenji; Ikeda, Naoshi*
Journal of Physics; Conference Series, 320, p.012085_1 - 012085_5, 2011/09
Times Cited Count：0 Percentile：0.03(Physics, Condensed Matter)In order to clarify the stability of charge ordered structure (CO) in charge- and spinfrustrated ferrite YbFeO, we have investigated changes of the CO structure by partial substitution of Mn for Fe in YbFeO by a transmission electron microscope (TEM), incombination with conventional dielectric measurement. It is revealed that subtle substitution of Mn for Fe in YbFeO destroyed drastically the CO structure with the wave vector of q=1/3 1/3 1/2 and, instead, induced polar clustering structure characterized by honeycomb shaped diffuse scatterings in the reciprocal space. The formation of polar clustering structure should be responsible for the characteristic dielectric dispersion.
Koyama, Tomofumi*; Shimizu, Hiroyuki*; Chijimatsu, Masakazu*; Nakama, Shigeo; Fujita, Tomoo
Proceedings of 2011 World Congress on Advances in Structural Engineering and Mechanics (ASEM '11plus) (USB Flash Drive), p.3759 - 3782, 2011/09
In this paper, the coupled thermal-mechanical processes in the sp pillar stability experiments (APSE) carried out by the Swedish Nuclear Fuel and Waste Management Company (SKB) were simulated using 2 dimensional Distinct Element Method (2-D DEM) with particles. The main objective for large scale in-situ experiment is to investigate the yielding strength of crystalline rock and the formation of the excavation disturbed/damaged zone (EDZ) during excavation of two boreholes, pressurizing in one of the borehole and heating processes. For the simulations, the heat flow algorism was newly introduced into original DEM code to consider heating processes in the APSE. For the DEM simulations, one of the borehole cross sections (in 2-D) was selected and modeled as an assemblage of many particles bonded each other to investigate the failure mechanism during excavation and heating processes in detail including crack propagation at the borehole surface. The microscopic parameters used in the DEM simulations were determined by the calibration using the laboratory uniaxial/triaxial compression testing results. The calculated stress distribution, displacements and temperature distribution were compared with the ones obtained from in-situ measurements and 2-D, 3-D FEM simulations. The simulated crack propagation during the excavation, pressurizing and heating processes by DEM with particles agrees qualitatively well with the observation. The parametric study for initial microcracks was performed to reproduce the spalling phenomena observed in the APSE.
