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Journal Articles

Structure of superconducting Ca-intercalated bilayer Graphene/SiC studied using total-reflection high-energy positron diffraction

Endo, Yukihiro*; Fukaya, Yuki; Mochizuki, Izumi*; Takayama, Akari*; Hyodo, Toshio*; Hasegawa, Shuji*

Carbon, 157, p.857 - 862, 2020/02

 Times Cited Count:0 Percentile:100(Chemistry, Physical)

no abstracts in English

Journal Articles

Total-reflection high-energy positron diffraction (TRHEPD) for structure determination of the topmost and immediate sub-surface atomic layers

Fukaya, Yuki; Kawasuso, Atsuo*; Ichimiya, Ayahiko*; Hyodo, Toshio*

Journal of Physics D; Applied Physics, 52(1), p.013002_1 - 013002_19, 2019/01

 Times Cited Count:2 Percentile:76.08(Physics, Applied)

no abstracts in English

Journal Articles

Research progress at the Slow Positron Facility in the Institute of Materials Structure Science, KEK

Hyodo, Toshio*; Wada, Ken*; Mochizuki, Izumi*; Kimura, Masao*; Toge, Nobukazu*; Shidara, Tetsuo*; Fukaya, Yuki; Maekawa, Masaki*; Kawasuso, Atsuo*; Iida, Shimpei*; et al.

Journal of Physics; Conference Series, 791(1), p.012003_1 - 012003_8, 2017/02

 Times Cited Count:2 Percentile:20.32

no abstracts in English

Journal Articles

Asymmetric structure of germanene on an Al(111) surface studied by total-reflection high-energy positron diffraction

Fukaya, Yuki; Matsuda, Iwao*; Feng, B.*; Mochizuki, Izumi*; Hyodo, Toshio*; Shamoto, Shinichi

2D Materials (Internet), 3(3), p.035019_1 - 035019_7, 2016/09

 Times Cited Count:24 Percentile:20.18(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Structure determination of the rutile-TiO$$_{2}$$(110)(1$$times$$2) surface using total-reflection high-energy positron diffraction (TRHEPD)

Mochizuki, Izumi*; Ariga, Hiroko*; Fukaya, Yuki; Wada, Ken*; Maekawa, Masaki*; Kawasuso, Atsuo*; Shidara, Tetsuo*; Asakura, Kiyotaka*; Hyodo, Toshio*

Hyomen Kagaku, 37(9), p.451 - 456, 2016/09

no abstracts in English

Journal Articles

Spacing between graphene and metal substrates studied with total-reflection high-energy positron diffraction

Fukaya, Yuki; Entani, Shiro; Sakai, Seiji; Mochizuki, Izumi*; Wada, Ken*; Hyodo, Toshio*; Shamoto, Shinichi

Carbon, 103, p.1 - 4, 2016/07

 Times Cited Count:12 Percentile:41.49(Chemistry, Physical)

no abstracts in English

Journal Articles

Structure determination of the rutile-TiO$$_{2}$$(110)-(1$$times$$2) surface using total-reflection high-energy positron diffraction (TRHEPD)

Mochizuki, Izumi*; Ariga, Hiroko*; Fukaya, Yuki; Wada, Ken*; Maekawa, Masaki; Kawasuso, Atsuo; Shidara, Tetsuo*; Asakura, Kiyotaka*; Hyodo, Toshio*

Physical Chemistry Chemical Physics, 18(10), p.7085 - 7092, 2016/03

 Times Cited Count:12 Percentile:31.9(Chemistry, Physical)

no abstracts in English

Journal Articles

Surface study with positron diffraction

Fukaya, Yuki; Hyodo, Toshio*

Hoshasen To Sangyo, (139), p.13 - 17, 2015/12

no abstracts in English

Journal Articles

Total reflection high-energy positron diffraction; An Ideal diffraction technique for surface structure analysis

Fukaya, Yuki; Maekawa, Masaki; Kawasuso, Atsuo; Mochizuki, Izumi*; Wada, Ken*; Shidara, Tetsuo*; Ichimiya, Ayahiko*; Hyodo, Toshio*

Applied Physics Express, 7(5), p.056601_1 - 056601_4, 2014/05

 Times Cited Count:15 Percentile:34.29(Physics, Applied)

no abstracts in English

Journal Articles

Reflection high-energy positron diffraction study on the first surface layer

Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi*; Wada, Ken*; Hyodo, Toshio*; Kawasuso, Atsuo

Journal of Physics; Conference Series, 505, p.012005_1 - 012005_6, 2014/04

 Times Cited Count:1 Percentile:41.7

no abstracts in English

Journal Articles

Total reflection high-energy positron diffraction (TRHEPD)

Hyodo, Toshio*; Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi*; Wada, Ken*; Shidara, Tetsuo*; Ichimiya, Ayahiko*; Kawasuso, Atsuo

Journal of Physics; Conference Series, 505(1), p.012001_1 - 012001_5, 2014/04

 Times Cited Count:5 Percentile:8.61

no abstracts in English

Journal Articles

Structure of silicene on a Ag(111) surface studied by reflection high-energy positron diffraction

Fukaya, Yuki; Mochizuki, Izumi*; Maekawa, Masaki; Wada, Ken*; Hyodo, Toshio*; Matsuda, Iwao*; Kawasuso, Atsuo

Physical Review B, 88(20), p.205413_1 - 205413_4, 2013/11

 Times Cited Count:54 Percentile:7.63(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Reflection high-energy positron diffraction; The Past 15 years and the future

Fukaya, Yuki; Maekawa, Masaki; Mochizuki, Izumi; Wada, Ken*; Hyodo, Toshio*; Kawasuso, Atsuo

Journal of Physics; Conference Series, 443(1), p.012068_1 - 012068_6, 2013/06

 Times Cited Count:11 Percentile:2.8

no abstracts in English

Journal Articles

Atomic configuration and phase transition of Pt-induced nanowires on a Ge(001) surface studied using scanning tunneling microscopy, reflection high-energy positron diffraction, and angle-resolved photoemission spectroscopy

Mochizuki, Izumi; Fukaya, Yuki; Kawasuso, Atsuo; Yaji, Koichiro*; Harasawa, Ayumi*; Matsuda, Iwao*; Wada, Ken*; Hyodo, Toshio*

Physical Review B, 85(24), p.245438_1 - 245438_6, 2012/06

 Times Cited Count:16 Percentile:36.7(Materials Science, Multidisciplinary)

The atomic configuration and electronic band structure of Pt-induced nanowires on a Ge(001) surface are investigated using scanning tunneling microscopy, reflection high-energy positron diffraction, and angle-resolved photoemission spectroscopy. A previously proposed theoretical model, composed of Ge dimers on the top layer and buried Pt arrays in the second and fourth layers, is found to be the fundamental structure of the observed nanowires. At low temperatures ($$T$$ $$<$$ 80 K), each Ge dimer is alternately tilted in the surface normal direction (asymmetric), causing a p($$4times4$$) periodicity. At high temperatures ($$T$$ $$>$$ 110 K), each Ge dimer is flat with respect to the horizontal axis (symmetric), giving rise to p ($$4times2$$) periodicity. Upon the above phase transition, the electronic band dispersion related to the Ge dimers in the deeper energy region shifts to the Fermi level.

Journal Articles

Increase in the beam intensity of the linac-based slow positron beam and its application at the Slow Positron Facility, KEK

Wada, Ken*; Hyodo, Toshio*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; Fukaya, Yuki; et al.

European Physical Journal D, 66(2), p.37 - 40, 2012/02

 Times Cited Count:32 Percentile:12.7(Optics)

no abstracts in English

Journal Articles

Reactions of free positrons in low temperature polyethylene; Delayed Ps formation and positron localization

Hirade, Tetsuya; Suzuki, Naoki*; Saito, Fuminori*; Hyodo, Toshio*

Physica Status Solidi (C), 4(10), p.3714 - 3717, 2007/09

 Times Cited Count:6 Percentile:16.05

Positronium (Ps) can be formed by a reaction of trapped electrons and free positrons at low temperatures in molecular solids. While Ps formation by Ore and spur process must be fast, Ps formation by trapped electrons and free positrons is possible even at later positron age. The evidence of this delayed Ps formation was obtained by age-momentum correlation measurement of electron-positron pair annihilation $$gamma$$-rays. In this work the $$S(t)$$ parameter curves measured with trapped electrons and no trapped electrons in polyethylene are interpreted by introducing possible positron reactions. Positrons that escape from Ps formation by the Ore and the spur processes have chance to form Ps with trapped electrons. This Ps formation competes with the positron localization resulting from the trapping between molecules or the weakly binding on molecules, ions, or radicals. Assuming the possibility of both the delayed Ps formation and delayed positron trapping and that S-parameters for ortho-Ps and free positrons are the same, we obtain a good fit to the observed time dependent S-parameter curves $$S(t)$$.

Journal Articles

Positronium formation reaction of trapped electrons and free positrons; Delayed formation studied by AMOC

Suzuki, Naoki*; Hirade, Tetsuya; Saito, Fuminori*; Hyodo, Toshio*

Radiation Physics and Chemistry, 68(3-4), p.647 - 649, 2003/10

 Times Cited Count:23 Percentile:16.49

no abstracts in English

Oral presentation

Positronium formation mechanism of trapped electrons and positrons

Hirade, Tetsuya; Suzuki, Naoki*; Saito, Fuminori*; Hyodo, Toshio*

no journal, , 

The electrons formed by ionization can be localized with 0.5-3eV at low temperatures (below -50$$^{circ}$$C) in some materials for long time. Positrons injected in liquids and molecular solids have a chance to form positronium with one of the excess electrons in the spur. However some of the positrons can escape from the positronium formation and they will annihilates from free positron state, usually. If there are weakly localized electrons in the materials at low temperatures, positrons will have the next chance to form positronium with these electrons. We showed that this positornium formation was slower than the positoronium formation in the spur. We have analyzed the data with considering the positron localization time and obtained several 10 ps as the localization time of positrons in polyethylene at 20K.

Oral presentation

The Status of reflection high-energy positron diffraction (RHEPD) apparatus at KEK

Fukaya, Yuki; Maekawa, Masaki; Wada, Ken*; Hyodo, Toshio*; Kawasuso, Atsuo

no journal, , 

no abstracts in English

Oral presentation

Recent development of the slow positron facility at institute of materials structure science, KEK

Wada, Ken*; Hyodo, Toshio*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Suzuki, Ryohei*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; et al.

no journal, , 

no abstracts in English

95 (Records 1-20 displayed on this page)