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Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.

Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08

 Times Cited Count:6 Percentile:30.34(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Development of evaluation method for variability of groundwater flow conditions associated with long-term topographic change and climate perturbations

Onoe, Hironori; Kosaka, Hiroshi*; Matsuoka, Toshiyuki; Komatsu, Tetsuya; Takeuchi, Ryuji; Iwatsuki, Teruki; Yasue, Kenichi

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.3 - 14, 2019/06

In this study, it is focused on topographic changes due to uplift and denudation, also climate perturbations, a method which is able to assess the long-term variability of groundwater flow conditions using the coefficient variation based on some steady-state groundwater flow simulation results was developed. Spatial distribution of long residence time area which is not much influenced due to long-term topographic change and recharge rate change during the past one million years was able to estimate through the case study of the Tono area, Central Japan. By applying this evaluation method, it is possible to identify the local area that has low variability of groundwater flow conditions due to topographic changes and climate perturbations from the regional area quantitatively and spatially.

Journal Articles

Production and decay of charmed baryons

Hosaka, Atsushi; Hiyama, Emiko; Kim, S.-H.*; Kim, H.-C.*; Nagahiro, Hideko*; Noumi, Hiroyuki*; Oka, Makoto; Shirotori, Kotaro*; Yoshida, Tetsuya*; Yasui, Shigehiro*

Nuclear Physics A, 954, p.341 - 351, 2016/10

 Times Cited Count:3 Percentile:24.93(Physics, Nuclear)

In this paper, we discuss reactions involving charmed baryons to explore their unique features. A well known phenomenon, the separation of the two internal motions of the $$rho$$ and $$lambda$$ types of a three-quark system is revisited. First we discuss the mass spectrum of low-lying excitations as functions of the heavy quark mass, smoothly connecting the $$SU(3)$$ and heavy quark limits. The properties of these modes can be tested in the production and decay reactions of the baryons. For the productions, we consider a one step process which excites dominantly $$lambda$$ mode excitations. We find abundant production rates for some of excited states. For decays, we study pion emission process, which provides a clean tool to test the structure of heavy quark systems due to well controlled low energy dynamics of the pion and quark. Both productions and decays of the charmed baryons are the issues of the future experiments at J-PARC.

Journal Articles

Spectrum of heavy baryons in the quark model

Yoshida, Tetsuya*; Hiyama, Emiko*; Hosaka, Atsushi*; Oka, Makoto; Sadato, Katsunori*

Physical Review D, 92(11), p.114029_1 - 114029_19, 2015/12

 Times Cited Count:209 Percentile:99.19(Astronomy & Astrophysics)

Single- and double-heavy baryons are studied in the constituent quark model. The model Hamiltonian is chosen as a standard one with two exceptions: (1) the color-Coulomb term depends on quark masses and (2) an antisymmetric $$LS$$ (spin-orbit) force is introduced. Model parameters are fixed by the strange baryon spectra, $$Lambda$$ and $$Sigma$$ baryons. The masses of the observed charmed and bottomed baryons are, then, fairly well reproduced. Our focus is on the low-lying negative-parity states, in which the heavy baryons show specific excitation modes reflecting the mass differences of heavy and light quarks. By changing quark masses from the SU(3) limit to the strange quark mass, and, further, to the charm and bottom quark masses, we demonstrate that the spectra change from the SU(3) symmetry patterns to the heavy-quark-symmetry ones.

Journal Articles

Compact XFEL and AMO sciences; SACLA and SCSS

Yabashi, Makina*; Tanaka, Hitoshi*; Tanaka, Takashi*; Tomizawa, Hiromitsu*; Togashi, Tadashi*; Nagasono, Mitsuru*; Ishikawa, Tetsuya*; Harries, J.; Hikosaka, Yasumasa*; Hishikawa, Akiyoshi*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164001_1 - 164001_19, 2013/08

 Times Cited Count:73 Percentile:94.70(Optics)

Journal Articles

An Attempt to evaluate horizontal crustal movement by geodetic and geological approach in the Horonobe area, northern Hokkaido, Japan

Tokiwa, Tetsuya; Asamori, Koichi; Niizato, Tadafumi; Nohara, Tsuyoshi; Matsuura, Yuki*; Kosaka, Hideki*

Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.407 - 413, 2010/10

In this study, we present the preliminary results for the estimation of a horizontal crustal movement by using geodetic and geological approach in the Horonobe area, northern Hokkaido, Japan. The estimations have been carried out by using a GPS data and a geological cross section obtained by applying balanced-section method. As results of this study, both of the shortening rates estimated by GPS data and balanced-section method indicate several millimeters per year. Namely, there is no contradiction between geodetic and geological data, and it is considered that Horonobe area is still situated similar tendency and magnitude of a crustal movement. Geodetic data is not usually used to evaluate the long-term crustal movement. However, the results of this study indicate that geodetic data provide valuable information for estimating the long-term crustal movement in the area.

Journal Articles

Magnetic circular dichroism of [Co/Pd] and [CoB/Pd] multilayered films

Agui, Akane; Asahi, Toru*; Sayama, Junichi*; Mizumaki, Masaichiro*; Tanaka, Masahito*; Osaka, Tetsuya*

Journal of Magnetism and Magnetic Materials, 320(22), p.3015 - 3018, 2008/11

 Times Cited Count:1 Percentile:5.70(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Existence and origin of compensation layer thickness in Tb$$_{20}$$Co$$_{80}$$/Pd multilayered films

Tanaka, Masahito*; Asahi, Toru*; Agui, Akane; Mizumaki, Masaichiro*; Sayama, Junichi*; Osaka, Tetsuya*

Journal of Physics D; Applied Physics, 41(5), p.055003_1 - 055003_4, 2008/03

 Times Cited Count:5 Percentile:22.12(Physics, Applied)

no abstracts in English

Journal Articles

Microscopic magnetic property of perpendicular magnetic films of Dy$$_{x}$$Co$$_{100-x}$$ measured using soft X-ray magnetic circular dichroism

Agui, Akane; Mizumaki, Masaichiro*; Asahi, Toru*; Matsumoto, Koji*; Morikawa, Tsuyoshi*; Sayama, Junichi*; Osaka, Tetsuya*

Journal of Physics and Chemistry of Solids, 68(11), p.2148 - 2152, 2007/11

 Times Cited Count:9 Percentile:40.74(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Soft X-ray absorption spectroscopy and magnetic circular dichroism study of electroless-deposited CoNiFe ternary alloy soft magnetic films

Tanaka, Masahito*; Nakamura, Naomichi*; Asahi, Toru*; Tsumori, Toshihiro*; Agui, Akane; Mizumaki, Masaichiro*; Osaka, Tetsuya*

Physica Status Solidi (C), 3(8), p.2783 - 2786, 2006/09

 Times Cited Count:1 Percentile:44.79(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Study on N$$_{2}$$-added and B-doped effect in Co/Pd multilayered films using soft X-ray absorption and magnetic circular dichroism

Agui, Akane; Asahi, Toru*; Sayama, Junichi*; Kawaji, Jun*; Mizumaki, Masaichiro*; Tanaka, Masahito*; Osaka, Tetsuya*

Journal of Physics D; Applied Physics, 39(14), p.2881 - 2885, 2006/07

 Times Cited Count:1 Percentile:4.30(Physics, Applied)

no abstracts in English

Journal Articles

Incident angle dependence of MCD at the Dy $$M$$$$_{5}$$-edge of perpendicular magnetic Dy$$_{x}$$Co$$_{100-x}$$ films

Agui, Akane; Mizumaki, Masaichiro*; Asahi, Toru*; Sayama, Junichi*; Matsumoto, Koji*; Morikawa, Tsuyoshi*; Matsushita, Tomohiro*; Osaka, Tetsuya*; Miura, Yoshimasa*

Journal of Alloys and Compounds, 408-412, p.741 - 745, 2006/02

 Times Cited Count:7 Percentile:45.42(Chemistry, Physical)

no abstracts in English

Journal Articles

MCD measurement at the Tb $$M$$$$_{4,5}$$-edges of Tb$$_{17}$$Fe$$_{x}$$Co$$_{(83-x)}$$ perpendicular magnetization films

Agui, Akane; Mizumaki, Masaichiro*; Asahi, Toru*; Sayama, Junichi*; Matsumoto, Koji*; Morikawa, Tsuyoshi*; Nakatani, Takeshi; Matsushita, Tomohiro*; Osaka, Tetsuya*; Miura, Yoshimasa*

Transactions of the Magnetics Society of Japan, 4(4-2), p.326 - 329, 2004/11

The electronic and spin state of the perpendicular magnetization film Tb$$_{17}$$Fe$$_{x}$$Co$$_{(83-x)}$$ was investigated by means of magnetic circular dichroism spectroscopy for each element. The samples are Tb$$_{17}$$Fe$$_{x}$$Co$$_{(83-x)}$$ while the ratio of a rare-earth metal Tb to transition metals Fe and Co is constant, the composition ratio of Fe and Co is changed. Changing the ratio, we estimated the expected orbital moments $$<$$$$L$$$$_{z}$$$$>$$ of Tb 4f electrons. The macroscopic magnetic property is studied from the microscopic point of view.

Journal Articles

Soft X-ray magnetic circular dichroism study of [Co/Pd] multilayered perpendicular magnetic films

Agui, Akane; Mizumaki, Masaichiro*; Matsushita, Tomohiro*; Asahi, Toru*; Kawaji, Jun*; Sayama, Junichi*; Osaka, Tetsuya*

Journal of Applied Physics, 95(12), p.7825 - 7831, 2004/06

 Times Cited Count:6 Percentile:27.38(Physics, Applied)

The electronic and spin states of [Co/Pd] multilayered perpendicular magnetization films with various seedlayers have been investigated by means of soft X-ray absorption and magnetic circular dichroism spectroscopy at the Co ${it L}$$$_{2,3}$$-edges. The expectation values of the orbital angular momentum $$<$$${it L}$$$_{z}$$$$>$$ and the spin angular momentum $$<$$${it S}$$$_{z}$$$$>$$ of Co atom in the [Co/Pd] multilayered film were estimated using the sum rule. It was found that the seedlayer changes macroscopic magnetic properties of the [Co/Pd] multilayered film without affecting the electronic and spin states of the upper layers of Co.

Oral presentation

Macroscopic and element selective magnetic properties of TbCo/Pd multilayered and single layered film

Tanaka, Masahito*; Asahi, Toru*; Agui, Akane; Mizumaki, Masaichiro*; Sayama, Junichi*; Osaka, Tetsuya*

no journal, , 

We examined the macroscopic and element selective magnetic properties by Kerr hysteresis loop and X-ray magnetic circular dichroism (MCD) spectroscopy, respectively, of [Tb$$_{20}$$Co$$_{80}$$]$$_{20}$$/Pd multilayered films and Tb$$_{20}$$Co$$_{80}$$ single layered films with several TbCo layer thicknesses. We found that the macroscopic magnetic properties of TbCo/Pd and TbCo films were dependent on the TbCo layer thickness by Kerr effect measurement. We estimated the $$<$$Lz$$>$$, $$<$$Sz$$>$$ and $$<$$Lz$$>$$/$$<$$Sz$$>$$ values from MCD measurements at Co L2,3 edges. The values of $$<$$Lz$$>$$ and $$<$$Sz$$>$$ of both types of films were the almost same each other, while the clear distinction of Kerr effects was observed.

Oral presentation

Study of the methodology for estimation of the influence of long-term topographic and climate change on deep groundwater flow conditions in case of Tono area, 1; Estimatation of paleo-topographic features and paleo-climate for several hundreds of thousand years and geological modeling based on field investigations

Onoe, Hironori*; Shiomi, Tetsuya*; Kusano, Tomohiro; Yasue, Kenichi; Kosaka, Hiroshi; Saegusa, Hiromitsu; Takeuchi, Ryuji; Tajikara, Masayoshi*

no journal, , 

To study the methodology for estimation of the influence of long-term topographic and climate change on deep groundwater flow condition, we estimated of paleo-topography and paleo-climate for past several hundred thousand years based on data from research and field investigations and built geological structured model that considered paleo-topography distribution in case of Gifu Tono area. As a result, we showed technique to restore paleo-topography distribution for three dimensions from fluvial terrace surface data dotted along a river in utilizing DEM data and GIS. In addition, we showed estimate method of climate of glacial epoch and quantity of cultivation of groundwater by near-surface hydrological observation data, pollen fossil analysis and expenditure calculation based on them. Furthermore, we built three-dimensional geological structured model that was base on carrying out groundwater flow analysis by utilizing bygones information.

Oral presentation

Examination of an investigation technique for activity on a fault-related fold in the Tenpoku region, northern Hokkaido, Japan

Nohara, Tsuyoshi; Kosaka, Hideki*; Kagohara, Kyoko*; Miwa, Atsushi*; Tokiwa, Tetsuya; Imaizumi, Toshifumi*

no journal, , 

Activity in the fault-related fold zone in the Tenpoku region, where the influence of the interplate coupling is comparatively small, has been investigated to explain the contradiction between geomorphological and geodetic information. Moreover, the actual average shortening rate of the Sarobetsu fault zone was investigated using the balanced cross section analytical method that used 2D Move. The results of this study show that the estimation of the long term crustal shortening rate in a fault-related fold zone, based on information from the geological structure, is important. In this study, it has been confirmed that information on the deformation of the geological structure is consistent to information on the tectonic landform. A multiple lines of evidence approach, including geomorphological, geological and geodetic investigation methods, will reduce uncertainty related to the average shortening rate along the fault of the fault-related fold.

Oral presentation

Estimate of long-term change of groundwater flow characteristic by topography change and climate change; In Tono area

Kusano, Tomohiro; Yasue, Kenichi; Kosaka, Hiroshi; Saegusa, Hiromitsu; Takeuchi, Ryuji; Onoe, Hironori*; Shiomi, Tetsuya*; Tajikara, Masayoshi*

no journal, , 

In this study, we focused on long-term topography change due to uplift, denudation and climate change with ice age and interglacial cycles of natural phenomena, to estimate influence to groundwater flow characteristics, we estimated paleo-topography and paleo-climate and operated groundwater flow simulation in Tono area. Based on terrace area distribution scattered along river, we estimated paleo-topography in three dimensions with DEM data and GIS. we estimated climate of glacial and interglacial age by near-surface hydrological observation data, pollen fossil analysis and expenditure calculation based on them. In hydraulics geological structure model with paleo-topography, we operated groundwater flow simulation on three-dimensional saturation and unsaturation in steady state. It is thought less effect on groundwater flow characteristics change in current terrain from middle terrace area formation. It is important to evaluate influence of groundwater flow characteristics if that form mountains or hills. Change in groundwater flow characteristics with change of recharge rate is limited to high-altitude area compared to ramifications of the mountains.

Oral presentation

Development of gamma-ray induced positron annihilation lifetime spectroscopy at UVSOR

Taira, Yoshitaka*; Fujimoto, Masaki*; Fujimori, Kosuke*; Kitaura, Mamoru*; Zen, H.*; Okano, Yasuaki*; Hosaka, Masahito*; Yamazaki, Junichiro*; Kato, Masahiro*; Hirade, Tetsuya; et al.

no journal, , 

For general positron sources, radioisotopes such as $$^{22}$$Na are often used. However, there is a problem that positrons cannot probe the deep region of metal materials with a thickness of 1 mm or more. Gamma-ray induced positron annihilation lifetime measurement (GiPALS) is a method for generating positrons in bulk samples with a thickness of several centimeters and samples placed in vessels such as high temperature and/or pressure furnaces. The annihilation lifetime of positrons is about 200 ps for metal materials, so it is important to use gamma rays with a shorter pulse width for GiPALS in order to accurately measure the positron lifetime. We have succeeded in the proof-of-principle experiment for GiPALS of ultra-short pulse gamma rays with a pulse width of 2 ps, which was originally developed using 90$$^{circ}$$ collision laser Compton scattering at UVSOR.

Oral presentation

Development of gamma-ray induced positron annihilation lifetime spectroscopy

Taira, Yoshitaka*; Fujimoto, Masaki*; Fujimori, Kosuke*; Kitaura, Mamoru*; Zen, H.*; Okano, Yasuaki*; Hosaka, Masahito*; Yamazaki, Junichiro*; Kato, Masahiro*; Hirade, Tetsuya; et al.

no journal, , 

For general positron sources, radioisotopes such as $$^{22}$$Na are often used. However, there is a problem that positrons cannot probe the deep region of metal materials with a thickness of 1 mm or more. Gamma-ray induced positron annihilation lifetime measurement (GiPALS) is a method for generating positrons in bulk samples with a thickness of several centimeters and samples placed in vessels such as high temperature and/or pressure furnaces. The annihilation lifetime of positrons is about 200 ps for metal materials, so it is important to use gamma rays with a shorter pulse width for GiPALS in order to accurately measure the positron lifetime. We have succeeded in the proof-of-principle experiment for GiPALS of ultra-short pulse gamma rays with a pulse width of 2 ps, which was originally developed using 90$$^{circ}$$ collision laser Compton scattering at UVSOR.

33 (Records 1-20 displayed on this page)