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Journal Articles

Study on formation mechanism of {332}$$<$$113$$>$$ deformation twinning in metastable $$beta$$-type Ti alloy focusing on stress-induced $$alpha"$$ martensite phase

Cho, K.*; Morioka, Ryota*; Harjo, S.; Kawasaki, Takuro; Yasuda, Hiroyuki*

Scripta Materialia, 177, p.106 - 111, 2020/03

 Times Cited Count:3 Percentile:8.3(Nanoscience & Nanotechnology)

Journal Articles

Development of inter-digital H-mode drift-tube linac prototype with alternative phase focusing for a muon linac in the J-PARC muon g-2/EDM experiment

Nakazawa, Yuga*; Iinuma, Hiromi*; Iwata, Yoshiyuki*; Iwashita, Yoshihisa*; Otani, Masashi*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Yamazaki, Takayuki*; Yoshida, Mitsuhiro*; Kitamura, Ryo; et al.

Journal of Physics; Conference Series, 1350, p.012054_1 - 012054_7, 2019/12

 Times Cited Count:0 Percentile:100

An inter-digital H-mode drift-tube linac (IH-DTL) is developed in a muon linac at the J-PARC E34 experiment. IH-DTL will accelerate muons from 0.34 MeV to 4.5 MeV at a drive frequency of 324 MHz. Since IH-DTL adopts an APF method, with which the beam is focused in the transverse direction using the rf field only, the proper beam matching of the phase-space distribution is required before the injection into the IH-DTL. Thus, an IH-DTL prototype was fabricated to evaluate the performance of the cavity and beam transmission. As a preparation of the high-power test, tuners and coupler are designed and fabricated. In this paper, the development of the tuner and the coupler and the result of the low-power measurement will be presented.

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:100

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

Beam commissioning of muon beamline using negative hydrogen ions generated by ultraviolet light

Nakazawa, Yuga*; Bae, S.*; Choi, H.*; Choi, S.*; Iijima, Toru*; Iinuma, Hiromi*; Kawamura, Naritoshi*; Kitamura, Ryo; Kim, B.*; Ko, H. S.*; et al.

Nuclear Instruments and Methods in Physics Research A, 937, p.164 - 167, 2019/09

 Times Cited Count:1 Percentile:58.8(Instruments & Instrumentation)

A muon linac is under development for the precise measurement of the muon anomalous magnetic moment ($$g$$-2) and electric dipole moment (EDM) with a reaccelerated thermal muon beam. An H$$^-$$ source driven by an ultraviolet light has been developed for the muon acceleration experiment. Prior to the acceleration experiment, a beamline commissioning was performed using this H$$^-$$ beam, since the accelerated muon intensity is very low. We successfully measured the magnetic rigidity, which is essential for identifying the accelerated muons. This H$$^-$$ source is capable of utilizing as a general-purpose beam source for other beamline.

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

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:4 Percentile:25.43(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 $$^{107}$$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.

Journal Articles

Prototype of an Inter-digital H-mode Drift-Tube Linac for muon linac

Nakazawa, Yuga*; Iinuma, Hiromi*; Iwata, Yoshiyuki*; Iwashita, Yoshihisa*; Otani, Masashi*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Yamazaki, Takayuki*; Yoshida, Mitsuhiro*; Kitamura, Ryo*; et al.

Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.180 - 183, 2019/01

We have developed an Interdigital H-mode (IH) Drift-Tube Linac (DTL) design with an alternative phase focusing (APF) scheme for a muon linac, in order to measure the anomalous magnetic moment and electric dipole moment (EDM) of muons at the Japan Proton Accelerator Research Complex (J-PARC). The IH-DTL accelerates muons from beta 0.08 to 0.28 at an operational frequency of 324 MHz. The output beam emittances are calculated as 0.315 $$pi$$ and 0.195 $$pi$$ mm mrad in the horizontal and vertical directions, respectively, which satisfies the experimental requirement.

Journal Articles

Out-of-plane strain induced in a Moir$'e$ superstructure of monolayer MoS$$_{2}$$ and MoSe$$_{2}$$ on Au(111)

Yasuda, Satoshi; Takahashi, Ryosuke*; Osaka, Ryo*; Kumagai, Ryota*; Miyata, Yasumitsu*; Okada, Susumu*; Hayamizu, Yuhei*; Murakoshi, kei*

Small, 13(31), p.1700748_1 - 1700748_8, 2017/08

 Times Cited Count:7 Percentile:45.88(Chemistry, Multidisciplinary)

MoS$$_{2}$$ and MoSe$$_{2}$$ monolayers are grown on Au surface by chemical vapor deposition and it is demonstrated that the contact with a crystalline Au(111) surface gives rise to only out-of-plane strain in both MoS$$_{2}$$ and MoSe$$_{2}$$ layers, whereas no strain generation is observed on polycrystalline Au or SiO$$_{2}$$/Si surfaces. Scanning tunneling microscopy analysis provides information regarding consequent specific adsorption sites between lower S (Se) atoms in the S-Mo-S (Se-Mo-Se) structure and Au atoms via unique moir$'e$ superstructure formation for MoS$$_{2}$$ and MoSe$$_{2}$$ layers on Au(111). This observation indicates that the specific adsorption sites give rise to out-of-plane strain in the TMDC layers. Furthermore, it also leads to effective modulation of the electronic structure of the MoS$$_{2}$$ or MoSe$$_{2}$$ layer.

Journal Articles

Development of micro-structured fluorescent plates for high-resolution imaging

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Matsubayashi, Masahito

JPS Conference Proceedings (Internet), 11, p.020005_1 - 020005_6, 2016/11

Journal Articles

Using LiF crystals for high-performance neutron imaging with micron-scale resolution

Faenov, A.*; Matsubayashi, Masahito; Pikuz, T.*; Fukuda, Yuji; Kando, Masaki; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Sakai, Takuro; Shiozawa, Masahiro*; et al.

High Power Laser Science and Engineering, 3, p.e27_1 - e27_9, 2015/10

 Times Cited Count:7 Percentile:50.14(Optics)

Journal Articles

Effect of deflected inflow on flows in a strongly-curved 90 degree elbow

Iwamoto, Yukiharu*; Kusuzaki, Ryo*; Sogo, Motosuke*; Yasuda, Kazunori*; Yamano, Hidemasa; Tanaka, Masaaki

Proceedings of ASME-JSME-KSME Joint Fluids Engineering Conference 2015 (AJK 2015-FED) (USB Flash Drive), p.1767 - 1773, 2015/07

Wall pressure measurements and flow visualization were conducted for a 90 degree elbow of which the axis curvature radius became the same as its inner diameter (125 mm). A deflected inflow, having an almost constant velocity slope, was introduced. Ensemble averaged pressure distributions showed no normalized pressure difference in cases of Reynolds numbers of 320,000 and 500,000. Comparisons with uniform inlet flow case proved; low-pressure region at the intrados of the elbow was weakened whereas a high pressure region outside strengthened in the deflected inflow case. Pressure distribution downstream of the elbow increased at the inside until two diameters downstream from the elbow exit. Flow visualization showed the pressure increase from collision of a strengthened secondary flow of extrados convection. The unsteady pressure distribution showed a circumferential extent of a strongly fluctuating region in and downstream the elbow decreased, comparing with the uniform inlet flow case.

Journal Articles

Fabrication of fine imaging devices using an external proton microbeam

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Koka, Masashi; Sato, Takahiro; Ishii, Yasuyuki; Oshima, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 332, p.238 - 241, 2014/08

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

We have successfully fabricated novel microscopic imaging devices made from UV/EB curable resin using an external scanning proton microbeams. The devices are micro-structured fluorescent plates that consist of an array of micro-pillars that align periodically. The base material used in the pillars is UV/EB curable resin and each pillar contains phosphor grains. The pattern exposures were performed using a proton beam writing technique. The height of the pillars depends on the range of the proton beam. Optical microscopy and scanning electron microscopy have been used to characterize the samples. The results show that the fabricated fluorescent plates are expected to be high-spatial-resolution imaging devices.

Journal Articles

Observation of fallout deposition in an outdoor swimming pool 50 km away from the Fukushima Daiichi Nuclear Power Plant

Saegusa, Jun; Yasuda, Ryo; Kurikami, Hiroshi

Radiation Measurements, 60, p.53 - 58, 2014/01

 Times Cited Count:5 Percentile:51.92(Nuclear Science & Technology)

After the Fukushima Daiichi Nuclear Power Plant (NPP) accident, the fallout deposited in an outdoor swimming pool was observed. At a pool situated 50 km away from the NPP, the average concentrations of radiocesium for the water and sediment were quantified as 170 Bq L$$^{-1}$$ and 3.6$$times$$10$$^{5}$$ Bq kg$$^{-1}$$, respectively. Taking account of these concentrations and of the water balance in and around the pool, the deposition density of radiocesium, as of August 2011, was precisely estimated to be 0.32$$pm$$0.03 MBq m$$^{-2}$$ ($$k$$ = 1). The density corroborated the previous results obtained by the other methods, i.e., airborne surveys, in-situ Ge surveys and soil samplings at neighboring locations. The radioactivity concentrations of $$^{89}$$Sr, $$^{90}$$Sr, $$^{238}$$Pu and $$^{239+240}$$Pu in the water were all less than the minimum detectable activities - 2, 0.1, 0.002 and 0.002 Bq L$$^{-1}$$, respectively.

Journal Articles

Micromachining of commodity plastics by proton beam writing and fabrication of spatial resolution test-chart for neutron radiography

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Matsubayashi, Masahito; Kada, Wataru; Koka, Masashi; Sato, Takahiro; Okubo, Takeru; Ishii, Yasuyuki; et al.

Nuclear Instruments and Methods in Physics Research B, 306, p.299 - 301, 2013/07

 Times Cited Count:7 Percentile:41.73(Instruments & Instrumentation)

Journal Articles

Decontamination of outdoor school swimming pools in Fukushima after the nuclear accident in March 2011

Saegusa, Jun; Kurikami, Hiroshi; Yasuda, Ryo; Kurihara, Kazuo; Arai, Shigeki; Kuroki, Ryota; Matsuhashi, Shimpei; Ozawa, Takashi; Goto, Hiroaki; Takano, Takao; et al.

Health Physics, 104(3), p.243 - 250, 2013/03

 Times Cited Count:3 Percentile:68.05(Environmental Sciences)

After the Nuclear accident on March 2011, water discharge from many outdoor swimming pools in the Fukushima prefecture was suspended out of concern that radiocesium in the pool water would flow into farmlands. We have reviewed the existing flocculation method for decontaminating pool water and established a practical decontamination method by demonstrating the process at several pools in the Fukushima prefecture.

Journal Articles

A Line pair indicator made of Gd film for evaluating spatial resolution

Yasuda, Ryo; Matsubayashi, Masahito; Sakai, Takuro; Nojima, Takehiro; Iikura, Hiroshi; Katagiri, Masaki*; Takano, Katsuyoshi*; Pikuz, T.; Faenov, A.*

Physics Procedia, 43, p.196 - 204, 2013/00

 Times Cited Count:1 Percentile:41.32

Journal Articles

Investigation of the brightness enhancement using brightness enhancement films on a scintillator

Iikura, Hiroshi; Tsutsui, Noriaki*; Saito, Yasushi*; Nojima, Takehiro; Yasuda, Ryo; Sakai, Takuro; Matsubayashi, Masahito

Physics Procedia, 43, p.161 - 168, 2013/00

 Times Cited Count:2 Percentile:25.19

Journal Articles

Development of an imaging system for the observation of water behavior in a channel in PEFC

Nojima, Takehiro; Yasuda, Ryo; Takenaka, Nobuyuki*; Katagiri, Masaki*; Iikura, Hiroshi; Sakai, Takuro; Matsubayashi, Masahito

Physics Procedia, 43, p.282 - 287, 2013/00

 Times Cited Count:2 Percentile:25.19

We developed a new imaging system for observing the water distribution in Polymer Electrolyte Fuel Cell (PEFC) under operation. This imaging system realizes both low noise and high sensitivity imaging and it enables to obtain an image in relatively short exposure time. This imaging system consists of EM-CCD (Electron Multiplication-Charged Coupled Device) camera, a LiF/ZnS scintillator screen and slit system. The EM-CCD camera has wide dynamic range and high sensitivity. The brightness of the scintillator screen is about three times higher than that of conventional type. The slit system was used for reducing the white dot noise caused by primary and/or secondary prompt $$gamma$$ rays. A characteristic test of this imaging system using JARI (Japan Automobile Research Institute)-standard cell was carried out at TNRF. In the results of the test, qualitative and quantitative observation of water behavior in the channel of PEFC was archived by the new imaging system.

Journal Articles

Development of a high-performance optical system and fluorescent converters for high-resolution neutron imaging

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Matsubayashi, Masahito

Physics Procedia, 43, p.223 - 230, 2013/00

 Times Cited Count:0 Percentile:100

Journal Articles

Neutron radiography; Nondestructive testing by neutrons

Yasuda, Ryo

Elekutoronikusu Jisso Gakkai-Shi, 15(7), p.565 - 570, 2012/11

no abstracts in English

JAEA Reports

Guide for decontaminating swimming pool at schools

Matsuhashi, Shimpei; Kurikami, Hiroshi; Yasuda, Ryo; Takano, Takao; Seko, Noriaki; Naganawa, Hirochika; Kuroki, Ryota; Saegusa, Jun

JAEA-Testing 2011-007, 189 Pages, 2012/07


Because of TEPCO Fukushima Dai-ichi Nuclear Power Plant accident due to the Great East Japan Earthquake, a huge amount of radioactive materials was widely dispersed and precipitated into the environment. Swimming pools in Fukushima prefectures were contaminated with the radioactives. We JAEA carried out several demonstration tests to decontaminate the radioactives and discharge the pool water safely. We concluded the results obtained from the tests as "Guide for decontaminating swimming pool at school" and released it quickly. Following this, we also released the guide in English. This manuscript, as an experimental report of the swimming pool water decontamination, is consisted from the guide in Japanese and English prepared.

121 (Records 1-20 displayed on this page)