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Journal Articles

Structure of nitride layer formed on titanium alloy surface by N$$_{2}$$-gas exposure at high temperatures

Takeda, Yusuke; Iida, Kiyoshi*; Sato, Shinji*; Matsuo, Tadatoshi*; Nagashima, Yasuyuki*; Okubo, Nariaki; Kondo, Keietsu; Hirade, Tetsuya

JPS Conference Proceedings (Internet), 25, p.011023_1 - 011023_3, 2019/03

In this study, we prepared samples under two different conditions, (1) 810$$^{circ}$$C, for 600 min, and (2) 850$$^{circ}$$C, for 720 min. A depth-profile analysis of the surfaces of the samples is conducted through Doppler broadening (DB) measurements of positron annihilation $$gamma$$ rays using a slow positron beam. It was indicated that many of positrons annihilated in defects near the surface. According to the TEM image, there are nano-crystal grains near the surface and then positrons can diffuse in the grains and annihilate in defects at the grain boundaries. Furthermore, DB measurements indicated that there is a depth dependence on the chemical composition where positrons annihilate. EDS spectroscopy measurements also indicated that there is a depth dependence of impurities such as Vanadium. These results indicated change of the chemical composition at the grain boundaries.

Journal Articles

Structure of nitride layer formed on titanium alloy surface by N$$_{2}$$-gas exposure at high temperatures

Takeda, Yusuke; Iida, Kiyoshi*; Sato, Shinji*; Matsuo, Tadatoshi*; Nagashima, Yasuyuki*; Okubo, Nariaki; Kondo, Keietsu; Hirade, Tetsuya

Journal of Physics; Conference Series, 791(1), p.012022_1 - 012022_4, 2017/02

 Times Cited Count:1 Percentile:49.45

Titanium alloy is widely used for applications such as golf club heads and structural materials for aircrafts. The surface can be exceedingly hardened by nitriding treatment that initiates defects, but there are some difficulties on use of titanium nitride because the layer can be exfoliated by stress. Therefore, we prepared samples in two different treatment conditions, (1) 810$$^{circ}$$C 600 min and (2) 850$$^{circ}$$C 720 min and performed depth profile analysis of Doppler broadening of positron annihilation $$gamma$$-rays (DB) for these samples. According to a calculation of nitrogen diffusion depth, the nitride layer should be only about 0.05-0.1$$mu$$m. However, the depth profile analysis of the DB measurement indicated that the defects introduced by nitriding treatment extended to a depth of 0.5$$mu$$m.

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:3 Percentile:82.4

no abstracts in English

JAEA Reports

Decommissioning activities and R&D of nuclear facilities in the second midterm plan

Terunuma, Akihiro; Mimura, Ryuji; Nagashima, Hisao; Aoyagi, Yoshitaka; Hirokawa, Katsunori*; Uta, Masato; Ishimori, Yuu; Kuwabara, Jun; Okamoto, Hisato; Kimura, Yasuhisa; et al.

JAEA-Review 2016-008, 98 Pages, 2016/07

JAEA-Review-2016-008.pdf:11.73MB

Japan Atomic Energy Agency formulated the plan to achieve the medium-term target in the period of April 2010 to March 2015(hereinafter referred to as "the second medium-term plan"). JAEA determined the plan for the business operations of each year (hereinafter referred to as "the year plan"). This report is that the Sector of Decommissioning and Radioactive Waste Management has summarized the results of the decommissioning technology development and decommissioning of nuclear facilities which were carried out in the second medium-term plan.

Journal Articles

Development of high resistant anti-reflection coating by using Al$$_{2}$$O$$_{3}$$/SiO$$_{2}$$ multilayer

Ochi, Yoshihiro; Nagashima, Keisuke; Okada, Hajime; Tanaka, Momoko; Tateno, Ryo*; Furukawa, Yasuyuki*; Sugiyama, Akira

Proceedings of SPIE, Vol.8885, p.88851Z_1 - 88851Z_6, 2013/11

 Times Cited Count:4 Percentile:89.54

We designed and fabricated high damage-resistant AR coating using Al$$_{2}$$O$$_{3}$$/SiO$$_{2}$$ layers. As a result of irradiation test using 500 ps pulses at 1 kHz, the damage threshold of the AR coating was estimated to be over 36 J/cm$$^{2}$$ (average value). We also fabricated high reflection (HR) mirrors using Al$$_{2}$$O$$_{3}$$/SiO$$_{2}$$ layers added on Ta$$_{2}$$O$$_{5}$$/SiO$$_{2}$$ layers and measured damage threshold of them for 7 ns, 500 ps, and 1 ps pulses.

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:34 Percentile:86.14(Optics)

no abstracts in English

JAEA Reports

Conceptual design of Fusion Experimental Reactor(FER/ITER); Electron cyclotron wave system

Yamamoto, Takumi; Tsuneoka, Masaki; Sakamoto, Keishi; Kimura, Haruyuki; Nagashima, Takashi; *; Saito, Yasushi*; *; Ito, Yasuyuki*

JAERI-M 91-194, 41 Pages, 1991/11

JAERI-M-91-194.pdf:1.03MB

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

Oral presentation

The New experiment stations at KEK Slow Positron Facility

Wada, Ken*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Increase in the intensity and brightness enhancement of the slow positron beam and its application at the Slow Positron Facility, KEK

Wada, Ken*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Suwada, Tsuyoshi*; Furukawa, Kazuro*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Beam-line improvement and new experiment stations of KEK-IMSS slow-positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Beam-line improvement and recent results of KEK-IMSS slow-positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Present status of the KEK-IMSS Slow Positron Facility; A New beam-line branch and a rearrangement of the experiment stations

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Recent developments and results of the KEK slow positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Materials science at the KEK slow positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Introduction to the slow positron facility at KEK

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Michishio, Koji*; Terabe, Hiroki*; Iida, Shimpei*; Nagashima, Yasuyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Application of a linac-based intense slow-positron beam to diffraction experiments

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Shidara, Tetsuo*; Fukaya, Yuki; Maekawa, Masaki; Kawasuso, Atsuo; Michishio, Koji*; Terabe, Hiroki*; Iida, Shimpei*; et al.

no journal, , 

no abstracts in English

Oral presentation

High resistant multilayer coatings for thin-disk laser amplifier

Ochi, Yoshihiro; Nagashima, Keisuke; Maruyama, Momoko; Okada, Hajime; Sugiyama, Akira; Tateno, Ryo*; Furukawa, Yasuyuki*

no journal, , 

We designed and fabricated high resistant AR and HR coatings using Al$$_{2}$$O$$_{3}$$ layer for Yb:YAG tin-disk amplifier. The damage threshold fluences for 520 ps pulse (AR, HR) and 1.2 ps pulse (HR only) were measured by uncompressed and compressed pulses, respectively, from the regenerative amplifier in QUADRA-T. As results, the damage threshold fluence of the AR coating of Al$$_{2}$$O$$_{3}$$/SiO$$_{2}$$ multilayer was 75 J/cm$$^{2}$$ for 520 ps pulse. This is satisfied out target value 40 J/cm$$^{2}$$ to use in the amplifiers. For the HR coating, the highest damage threshold fluences, 2.4 J/cm$$^{2}$$ for 1.2 ps pulse and 123.6 J/cm$$^{2}$$ for 520 ps pulse, respectively, were obtained by manipulating Al$$_{2}$$O$$_{3}$$/SiO$$_{2}$$ layer thickness to set a point of the maximum electric field in the SiO$$_{2}$$ layer.

Oral presentation

Measurement of trace elements in an erythrocyte of myelodysplastic syndrome (MDS) using in-air micro-PIXE

Kasamatsu, Tetsuhiro*; Nagashima, Tomomi*; Nagai, Kiyoe*; Nagamine, Takeaki*; Murakami, Hirokazu*; Koka, Masashi; Yamada, Naoto; Kitamura, Akane; Sato, Takahiro; Yokoyama, Akihito; et al.

no journal, , 

no abstracts in English

Oral presentation

Analysis of surface structure of titanium alloy nitride by slow positron beam

Takeda, Yusuke; Iida, Kiyoshi*; Sato, Shinji*; Matsuo, Tadatoshi*; Nagashima, Yasuyuki*; Okubo, Nariaki; Kondo, Keietsu; Hirade, Tetsuya

no journal, , 

The impact stress exfoliates a Nitride surface layer on Titanium alloy prepared in some conditions. So we prepared specimens in two different conditions, (1) 810$$^{circ}$$C, 600min and (2) 850$$^{circ}$$C, 720min, and performed depth profile analysis of their surfaces with Doppler broadening measurements of positron annihilation $$gamma$$-rays (DB) that is sensitive for defects by Slow Positron beams. Although the specimens (2) is harder than (1) according to the Vickers Hardness test, DB results indicated that defect layer of specimen (1) is thicker than (2). It means that the defect layer thickness was not the cause of surface hardening. Furthermore, chemical elements at the positron annihilation sites could be analyzed qualitatively by DB and the change of the composition appeared in deeper region than the defect layer. The defect layer depth does not match the depth where chemical composition changes by DB appeared. TEM and EDS observation showed different tendency from the results by DB. It is because positrons probe specific sites, and the combination of these methods will be a strong tool to investigate surface structures.

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