Y
Yuichi Oki
Researcher at KEK
Publications - 23
Citations - 267
Yuichi Oki is an academic researcher from KEK. The author has contributed to research in topics: Irradiation & Positronium. The author has an hindex of 10, co-authored 22 publications receiving 260 citations.
Papers
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Journal ArticleDOI
Positron irradiation effects on polypropylene and polyethylene studied by positron annihilation
TL;DR: In this article, the effects of positron irradiation on polypropylene (PP) and polyethylene (PE) have been studied using the positron source for positron annihilation (PA) experiments.
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Radiation hardness of cerium-doped gadolinium silicate Gd2SiO5:Ce against high energy protons, fast and thermal neutrons
Masaaki Kobayashi,Masaharu Ieiri,Kenjiro Kondo,Taichi Miura,Hiroyuki Noumi,Masaharu Numajiri,Yuichi Oki,Takenori Suzuki,Minoru Takasaki,Kazuhiro Tanaka,Yutaka Yamanoi,Mitsuru Ishii +11 more
TL;DR: In this article, the degradation of Gd 2 SiO 5 :Ce in optical transmittance due to proton irradiation was negligibly small below 10 6 rad, smaller than 2%/cm at 10 7 rad and large at 10 8 rad.
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Radiation effect on polypropylene studied by the relaxational behaviour at low temperature using positron annihilation
Takenori Suzuki,Yuichi Oki,Masaharu Numajiri,Taichi Miura,Kenjiro Kondo,Nagayasu Oshima,Yasuo Ito +6 more
TL;DR: In this paper, the irradiation effect of γ-rays on polypropylene (PP) has been studied through relaxational behaviour, using the positron annihilation lifetime (PAL) method.
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Free-volume characteristics and water absorption of novolac epoxy resins investigated by positron annihilation
Takenori Suzuki,Yuichi Oki,Masaharu Numajiri,Taichi Miura,Kondo Kondo,Yutaka Shiomi,Yasuo Ito +6 more
TL;DR: A positron-annihilation lifetime technique was applied to four kinds of epoxy resin (cresol novolac, trishydroxy-phenyl-methane (THPM), tetra-methyl-biphenol and bis-phenol A) in order to study the relation between the intermolecular-space holes and water absorption as mentioned in this paper.
Journal ArticleDOI
Effects of aging and oxidation on positronium formation in polyethylenes
Takenori Suzuki,Yuichi Oki,Masaharu Numajiri,Taichi Miura,Kenjiro Kondo,Yasuo Ito,Yutaka Shiomi +6 more
TL;DR: In this paper, it was shown that the intensity, I 3, of the long-lived component of positronium (Ps) shows hystereses between the heating and cooling processes due to aging effect.