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Journal Articles

Negative muonium ion production with a C12A7 electride film

Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Matoba, Shiro*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Hasegawa, Kazuo; et al.

Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12

 Times Cited Count:0 Percentile:0.07

Negative muonium atom ($$mu^+$$e$$^-$$e$$^-$$, Mu$$^-$$) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented. Measured production rate of the Mu$$^-$$ were 10$$^{-3}$$/s for all the Al, electride, and SUS target. Significant enhancement on electride target was not observed, thus it is presumed that the surface condition should be more carefully treated. There was no material dependence of the Mu$$^-$$ averaged energy: it was 0.2$$pm$$0.1keV.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:140 Percentile:99.81(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

First muon acceleration using a radio-frequency accelerator

Bae, S.*; Choi, H.*; Choi, S.*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Hasegawa, Kazuo; Iijima, Toru*; Iinuma, Hiromi*; Ishida, Katsuhiko*; Kawamura, Naritoshi*; et al.

Physical Review Accelerators and Beams (Internet), 21(5), p.050101_1 - 050101_6, 2018/05

 Times Cited Count:11 Percentile:81.67(Physics, Nuclear)

Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu$$^{-}$$), which are bound states of positive muons and two electrons, are generated from through the electron capture process in an aluminum degrader. The generated Mu$$^{-}$$'s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu$$^{-}$$'s are accelerated to 89 keV. The accelerated Mu$$^{-}$$'s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Journal Articles

High-resolution Compton cameras based on Si/CdTe double-sided strip detectors

Odaka, Hirokazu*; Ichinohe, Yuto*; Takeda, Shinichiro*; Fukuyama, Taro*; Hagino, Koichi*; Saito, Shinya*; Sato, Tamotsu*; Sato, Goro*; Watanabe, Shin*; Kokubun, Motohide*; et al.

Nuclear Instruments and Methods in Physics Research A, 695, p.179 - 183, 2012/12

 Times Cited Count:19 Percentile:84.11(Instruments & Instrumentation)

We have developed a new Si/CdTe semiconductor double-sided strip detector (DSD) Compton camera. The camera consists of a 500-$$mu$$m-thick Si-DSD and four layers of 750-$$mu$$m-thick CdTe-DSDs all of which have common electrode configuration segmented into 128 strips on each side with pitches of 250$$mu$$m. In order to realize high angular resolution and to reduce size of the detector system, a stack of DSDs with short stack pitches of 4 mm is utilized to make the camera. Taking advantage of the excellent energy and position resolutions of the semiconductor devices, the camera achieves high angular resolutions of 4.5 degrees at 356 keV and 3.5 degrees at 662 keV. To obtain such high resolutions together with an acceptable detection efficiency, we demonstrate data reduction methods including energy calibration using Compton scattering continuum and depth sensing in the CdTe-DSD. We also discuss imaging capability of the camera and show simultaneous multi-energy imaging.

Journal Articles

Applications and imaging techniques of a Si/CdTe Compton $$gamma$$-ray camera

Takeda, Shinichiro*; Ichinohe, Yuto*; Hagino, Koichi*; Odaka, Hirokazu*; Yuasa, Takayuki*; Ishikawa, Shinnosuke*; Fukuyama, Taro*; Saito, Shinya*; Sato, Tamotsu*; Sato, Goro*; et al.

Physics Procedia, 37, p.859 - 866, 2012/10

 Times Cited Count:16 Percentile:98.04

By using new Compton camera consisting of silicon double-sided strip detector (Si-DSD) and CdTe-DSD developed for the ASTRO-H mission, an experiment was conducted to study its feasibility for advanced hotspot monitoring. In addition to hotspot imaging already provided by commercial imaging systems, the identification of the variety of radioisotopes is realized thanks to the good energy resolution given by the semiconductor detectors. Three radioisotopes of $$^{133}$$Ba (356 keV), $$^{22}$$Na (511 keV) and $$^{137}$$Cs (662 keV) were individually imaged by applying event selection in the energy window and the $$gamma$$-ray images was correctly overlapped by an optical picture. The detection efficiency of 1.68$$times$$10$$^{-4}$$ (effective area: 1.7$$times$$10$$^{-4}$$ cm$$^2$$) and angular resolution of 3.8$$^{circ}$$ were obtained by stacking five detector modules for 662 keV $$gamma$$-ray. The higher detection efficiency required in a specific use can be achieved by stacking more detector modules.

JAEA Reports

Maintenance of used components in spallation neutron source; Moderator $$cdot$$ reflector and proton beam window

Teshigawara, Makoto; Kinoshita, Hidetaka; Wakui, Takashi; Meigo, Shinichiro; Seki, Masakazu; Harada, Masahide; Ito, Manabu; Suzuki, Toru; Ikezaki, Kiyomi; Maekawa, Fujio; et al.

JAEA-Technology 2012-024, 303 Pages, 2012/07

JAEA-Technology-2012-024.pdf:46.04MB

3 GeV Protons with 1 MW beam power are irradiated to mercury target of spallation neutron source in Materials and Life science Facility (MLF), which is one of facilities of J-PARC. Irradiated components, such as target container, moderator, reflector and proton beam window, are needed to replace periodically due to irradiation damage of high energy protons and neutrons. These used components are replaced remotely because of highly activated. Maintenance scenario was settled so as to handle these components. Required remote handling machines were designed and installed in hot cell and other room of the MLF. We performed remote handling tests by using actual components to confirm the design. We report results, such as replacement procedure, trouble and its solution, etc., for moderator, reflector and proton beam window in order to provide the handling of actual used components.

Journal Articles

Experimental results of the $$gamma$$-ray imaging capability with a Si/CdTe semiconductor Compton camera

Takeda, Shinichiro*; Aono, Hiroyuki*; Okuyama, Sho*; Ishikawa, Shinnosuke*; Odaka, Hirokazu*; Watanabe, Shin*; Kokubun, Motohide*; Takahashi, Tadayuki*; Nakazawa, Kazuhiro*; Tajima, Hiroyasu*; et al.

IEEE Transactions on Nuclear Science, 56(3), p.783 - 790, 2009/06

 Times Cited Count:47 Percentile:95.74(Engineering, Electrical & Electronic)

JAEA Reports

Design study on a demonstration core for a practical LMFBR in Monju, 2

Saito, Kosuke; Maeda, Seiichiro; Higuchi, Masashi*; Takano, Mitsuhiro*; Nakazawa, Hiroaki

JAEA-Technology 2006-035, 76 Pages, 2006/06

JAEA-Technology-2006-035.pdf:5.25MB

Because of the revision on the standardized strength of the ODS steel, the previous design study of MONJU demonstrative core has been obliged to be reconsidered. For economical advantages, only a 127 pins-bundle core was selected to be redesigned. For the sake of cladding endurance, the ratio of cladding thickness to outer diameter was reset incrementally followed by the determination of the basic specification of a pin. Notwithstanding some deterioration thanks to the reduction of a fuel volume fraction, the prospect in neutronics was obtained. Coolant flow distribution design which was based on power distribution was successfully carried out without overheating cladding. Average burn-up of 150 GWd/t and 380 days-long operational period per cycle are to be attained, and the designed core can thermally afford to receive test fuels. The study has necessity to be advanced extensively for the purpose of materialization according to the circumstances of MONJU in future.

Journal Articles

Development and demonstration of ATR-MOX fuel

Abe, Tomoyuki; Maeda, Seiichiro; Nakazawa, Hiroaki

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13), 0 Pages, 2005/05

Japan Nuclear Cycle Development Institute (JNC) developed plutonium and uranium mixed oxide (MOX) fuels for an advanced thermal reactor (ATR) for a flexible utilization of plutonium. JNC made endeavors to obtain well-homogenized MOX pellets by a ball mill mixing method with a variety of raw powders, including MOX powder by a microwave-heating denitration process. A total of 772 MOX fuel assemblies were utilized in the ATR prototype reactor

Journal Articles

Admixture of excited states and ground states of a Eu$$^{3+}$$ ion in Eu$$_{3}$$Fe$$_{5}$$O$$_{12}$$ by means of magnetic circular dichroism

Mizumaki, Masaichiro*; Uozumi, Takayuki*; Agui, Akane; Kawamura, Naomi*; Nakazawa, Makoto*

Physical Review B, 71(13), p.134416_1 - 134416_8, 2005/04

 Times Cited Count:13 Percentile:51.5(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Development of advanced blanket materials for a solid breeder blanket of a fusion reactor

Kawamura, Hiroshi; Ishitsuka, Etsuo; Tsuchiya, Kunihiko; Nakamichi, Masaru; Uchida, Munenori*; Yamada, Hirokazu*; Nakamura, Kazuyuki; Ito, Haruhiko; Nakazawa, Tetsuya; Takahashi, Heishichiro*; et al.

Nuclear Fusion, 43(8), p.675 - 680, 2003/08

 Times Cited Count:26 Percentile:63.92(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

ATR-MOX Fuel Design and Development

Maeda, Seiichiro; Abe, Tomoyuki; Nakazawa, Hiroaki

GENES4/ANP2003, CD-ROM, Paper1150, 8p., 8 Pages, 2003/00

None

Journal Articles

MCD studies in 2p and 3d XAS of La$$_{1-x}$$Sr$$_{x}$$CoO$$_{3}$$

Mizumaki, Masaichiro*; Yoshii, Kenji; Kawamura, Naomi*; Nakazawa, Makoto*

Surface Review and Letters, 9(2), p.855 - 859, 2002/04

 Times Cited Count:1 Percentile:8.02(Chemistry, Physical)

no abstracts in English

JAEA Reports

Study on solubility and leaching property of iodine-129 waste-forms for geological disposal

Yanagisawa, Ichiro*; Katsurai, Kiyomichi*; Izumi, Jun*; Saigusa, Moriyuki*; Kitao, Hideo*; Tsuzuki, Yasuo*; Neyama, Atsushi*; Kato, Hiroyasu*; Nakazawa, Toshiyuki*; Okada, Kenichi*

JNC TJ8400 2000-037, 61 Pages, 2000/02

JNC-TJ8400-2000-037.pdf:2.78MB

no abstracts in English

Journal Articles

Impurity behavior during the H-mode in JFT-2M

Ogawa, Hiroaki; Kasai, Satoshi; Tamai, Hiroshi; Kawashima, Hisato; *; Yamauchi, Toshihiko; Mori, Masahiro; Miura, Yukitoshi; Suzuki, Norio; Sengoku, Seio; et al.

Journal of the Physical Society of Japan, 59(11), p.3962 - 3976, 1990/11

 Times Cited Count:4 Percentile:46.79(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Ion Bernstein wave experiment on JFT-2M tokamak

Tamai, Hiroshi; Ogawa, Toshihide; Matsumoto, Hiroshi; Odajima, Kazuo; ; Hoshino, Katsumichi; Kasai, Satoshi; Kawakami, Tomohide; Kawashima, Hisato; Kondoh, Takashi; et al.

Japanese Journal of Applied Physics, 29(10), p.L1911 - L1914, 1990/10

 Times Cited Count:1 Percentile:10.21(Physics, Applied)

no abstracts in English

Journal Articles

H mode observed in the JFT-2M tokamak with edge heating by electron cyclotron waves

Hoshino, Katsumichi; Yamamoto, Takumi; Kawashima, Hisato; Suzuki, Norio; Uesugi, Yoshihiko; Mori, Masahiro; ; Kasai, Satoshi; Kawakami, Tomohide; Matsuda, Toshiaki; et al.

Physical Review Letters, 63(7), p.770 - 773, 1989/08

 Times Cited Count:24 Percentile:80.58(Physics, Multidisciplinary)

no abstracts in English

JAEA Reports

Observation of H-mode by edge heating solely by electron cyclotron heating in a divertor configuration of JFT-2M tokamak

Hoshino, Katsumichi; Yamamoto, Takumi; Kawashima, Hisato; Suzuki, Norio; Uesugi, Yoshihiko; ; Kasai, Satoshi; Kawakami, Tomohide; Matsuda, Toshiaki; Miura, Yukitoshi; et al.

JAERI-M 89-038, 7 Pages, 1989/03

JAERI-M-89-038.pdf:0.29MB

no abstracts in English

JAEA Reports

Characteristics of edge localized mode in JFT-2M H-mode

Matsumoto, Hiroshi; R.J.Goldston*; ; Hoshino, Katsumichi; Kawashima, Hisato; Kawakami, Tomohide; Maeda, Hikosuke; Matoba, Toru; Matsuda, Toshiaki; Miura, Yukitoshi; et al.

JAERI-M 89-020, 26 Pages, 1989/03

JAERI-M-89-020.pdf:1.0MB

no abstracts in English

Journal Articles

Pump limiter experiment on JFT-2M tokamak

Sengoku, Seio; ; Hoshino, Katsumichi; Kasai, Satoshi; Kawakami, Tomohide; Kawashima, Hisato; Kondo, Takashi*; Maeda, Hikosuke; Matsuda, Toshiaki; Matsumoto, Hiroshi; et al.

Journal of Nuclear Materials, 162-164, p.667 - 673, 1989/00

 Times Cited Count:4 Percentile:49.89(Materials Science, Multidisciplinary)

no abstracts in English

36 (Records 1-20 displayed on this page)