Activity enhancement of platinum oxygen-reduction electrocatalysts using ion-beam induced defects

Kimata, Tetsuya*; Kakitani, Kenta*; Yamamoto, Shunya*; Shimoyama, Iwao; Matsumura, Daiju; Iwase, Akihiro*; Mao, W.*; Kobayashi, Tomohiro*; Yamaki, Tetsuya*; Terai, Takayuki*

Physical Review Materials (Internet), 6(3), p.035801_1 - 035801_7, 2022/03

https://doi.org/10.1103/PhysRevMaterials.6.035801

Changes in electronic structure of carbon supports for Pt catalysts induced by vacancy formation due to Ar irradiation

Okazaki, Hiroyuki*; Kakitani, Kenta*; Kimata, Tetsuya*; Idesaki, Akira*; Koshikawa, Hiroshi*; Matsumura, Daiju; Yamamoto, Shunya*; Yamaki, Tetsuya*

Journal of Chemical Physics, 152(12), p.124708_1 - 124708_5, 2020/03

https://doi.org/10.1063/1.5144568

Platinum nanoparticles on the glassy carbon surface irradiated with argon ions

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Kobayashi, Tomohiro*; Terai, Takayuki*

Surface & Coatings Technology, 306(Part A), p.123 - 126, 2016/11

https://doi.org/10.1016/j.surfcoat.2016.05.042

Platinum (Pt) nanoparticle catalysts with oxygen reduction reaction (ORR) activity are required for practical applications of polymer electrolyte fuel cells. We prepared Pt nanoparticles on an Ar-irradiated glassy carbon (GC) surface by a radio-frequency magnetron sputtering method to investigate the influence of the ion-induced lattice defects in GC on the ORR activity of the deposited Pt nanoparticles. Interestingly, the Pt nanoparticles on the irradiated surface exhibited ca. 2.5 times higher specific activity than those on the non-irradiated one. X-ray photoelectron spectroscopy suggested the interfacial Pt-C interaction occurring between the irradiated GC and Pt nanoparticles, which should be a reason for improvement of the ORR activity.

Sagittal focusing of synchrotron radiation X-rays using a winged crystal

Nisawa, Atsushi*; Yoneda, Yasuhiro; Ueno, Go*; Murakami, Hironori*; Okajima, Yuka*; Yamamoto, Kenichiro*; Semba, Yasunori*; Uesugi, Kentaro*; Tanaka, Yoshihito*; Yamamoto, Masaki*; et al.

Journal of Synchrotron Radiation, 20(2), p.219 - 225, 2013/03

https://doi.org/10.1107/S0909049512049813

A Si(111) winged crystal has been designed to minimize anticlastic bending and improve sagittal focusing efficiency. The crystal was thin with wide stiffening wings. The length-to-width ratio of the crystal was optimized by finite element analysis, and the optimal value was larger than the "golden value". The analysis showed that the slope error owing to anticlastic bending is less than the Darwin width. The X-rays were focused two-dimensionally using the crystal and a tangentially bent mirror. The observed profiles of the focal spot agreed well with the results of a ray-tracing calculation in the energy range from 8 to 17.5 keV. X-ray diffraction measurements with a high signal-to-noise ratio using this focusing system were demonstrated for a small protein crystal.

Precise and accurate determination of plutonium by controlled-potential coulometry and its uncertainty evaluation

Yamamoto, Masahiko; Ishibashi, Atsushi; Nagayama, Tetsuya; Surugaya, Naoki; Kurosawa, Akira; Hiyama, Toshiaki

JAEA-Technology 2010-040, 28 Pages, 2010/12

JAEA-Technology-2010-040.pdf:0.97MB

Precise analysis of plutonium is necessary for material control and safeguards in nuclear facility. Thus, controlled-potential coulometry, which yields absolute results and high precision, was applied for the determination of plutonium. The coulometry system and sample pretreatment procedures were optimized following ISO12183:2005. Plutonium sample prepared from NBL CRM-126 Pu metal was measured and agreed well with certified value. For spike preparation of isotope dilution mass spectrometry (IDMS), plutonium solution was prepared from MOX powder. Plutonium content was 15.5995 mgPu/g. The uncertainty was calculated by ISO/BIPM Guide to the Expression of Uncertainties in Measurements. The relative expanded uncertainty was 0.023% with confidence interval of 95%. The results were in good agreement with those obtained by IDMS. Thus the proposed coulometry method was successfully applied for the determination of plutonium at the highest level of precision and accuracy.

Acceleration of high current fully stripped carbon ion beam by direct injection scheme

Kashiwagi, Hirotsugu; Fukuda, Mitsuhiro; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; et al.

Review of Scientific Instruments, 77(3), p.03B305_1 - 03B305_4, 2006/03

https://doi.org/10.1063/1.2172358

Acceleration of a 17mA 100keV/u C ion beam has been successfully achieved with an RFQ linac by means of "Direct injection scheme". The Direct injection scheme is a new scheme for injecting an ion beam from a laser ion source to the RFQ linac without a low energy beam transport line to avoid a beam loss due to the space charge effect. The high current C beam is required for single turn injection to a synchrotron to reduce the size of synchrotron magnets. The high current C beam produced by an ion source with a Nd-YAG laser was injected to the RFQ linac by the Direct injection scheme. It has been proved experimentally that the fully-stripped carbon ion beam with a current more than 10mA can be accelerated by the RFQ linac.

Acceleration of high current and highly charged carbon beam using direct injection scheme

Kashiwagi, Hirotsugu; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; Fujimoto, Tetsuya*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.182 - 184, 2005/07

The carbon beam from a Nd-YAG laser ion source was accelerated successfully by an RFQ linac using Direct injection scheme. The "Direct injection scheme" is the way to inject an ion beam to the RFQ linac without a low energy beam transport line to avoid space charge effect due to a high intensity beam from the laser ion source. About 30mA of a carbon beam was detected by a faraday cup just behind the RFQ linac.

Current clinical results of the Tsukuba BNCT trial

Yamamoto, Tetsuya*; Matsumura, Akira*; Nakai, Kei*; Shibata, Yasushi*; Endo, Kiyoshi*; Sakurai, Fumio; Kishi, Toshiaki; Kumada, Hiroaki; Yamamoto, Kazuyoshi; Torii, Yoshiya

Applied Radiation and Isotopes, 61(5), p.1089 - 1093, 2004/11

https://doi.org/10.1016/j.apradiso.2004.05.010

no abstracts in English

Development of computational dosimetry system and measurement of dose distribution in water head phantom for BNCT in JAERI

Kumada, Hiroaki; Yamamoto, Kazuyoshi; Torii, Yoshiya; Matsumura, Akira*; Yamamoto, Tetsuya*; Nakagawa, Yoshinobu*; Horiguchi, Yoji

JAERI-Conf 2001-017, p.357 - 362, 2001/11

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-2001-017.pdf

no abstracts in English

Study on evaluation of uncertainty due to geological environment

Ijiri, Yuji*; Hattori, Hiromichi*; Suzuki, Shunichi*; Oishi, Masaya*; Kubota, Shigeru*; Adachi, Tetsuya*; Yamamoto, Takuya*

JNC TJ8400 2001-010, 143 Pages, 2001/03

JNC-TJ8400-2001-010.pdf:17.19MB

The evaluation of uncertainty of geological environment is a key issue in assessing a performance of a deep geological disposal system for high-level nuclear waste. The geological environment uncertainty is arose from data obtained from surveys and model used for a performance assessment.The objectives of this study is to develop a rational planning methodology of site characterization using the Horonobe site as a model case, and to establish a modeling methodology using the Tono site as a model case. At the Horonobe site, first, a conceptual model is constructed based on the information at every stage of site characterization procedure. A sensitivity analysis is performed using various conceptual models and data. If conceptual models uncertainty have a great impact on the result of performance assessment analysis, surveys that detect the most appropriate conceptual model are conducted in the next stage of site characterization. If data uncertainty have a great impact on the result of performance assessment analysis, surveys that decrease the data uncertainty are conducted. Thus, a rational site characterization methodology in which the most sensitive items are preferentially detected in the next stage of site characterization is developed. This concept of a rational site characterization methodology is described in this report. In addition, preliminary conceptual model is developed based on geological information around Horonobe site, and data uncertainty for the sensitivity analysis which will be conducted in next year is investigated. At the Tono site, literature on model uncertainty is surveyed, and data obtained at the Tono site is reviewed from modeling point of view.