Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 180

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Impedance reduction by a SiC-loaded flange and its application to the J-PARC main ring septum magnet

Kobayashi, Aine*; Toyama, Takeshi*; Nakamura, Takeshi*; Shobuda, Yoshihiro; Ishi, Koji*

Nuclear Instruments and Methods in Physics Research A, 1031, p.166515_1 - 166515_12, 2022/05

 Times Cited Count:0 Percentile:0.06(Instruments & Instrumentation)

The beam power of the main ring of the Japan Proton Accelerator Research Complex (J-PARC) is currently being increased. For high-power beam realization, it is essential to suppress the beam instability that limits the beam power and to estimate and enact countermeasures against the beam coupling impedance of individual devices. The fast-extraction (FX) septum magnet will be replaced with another magnet that copes with higher numbers of repetition cycles. Despite their different structures, both septa demonstrated a large impedance in estimates performed by the CST studio suite wake-field solver. The widely used taper impedance-reduction method would be effective but receives spatial constraints. By attaching a copper plate and SiC to the flange of the septum magnet, we could effectively reduce the impedance. The copper plate on the flange reduces the impedance below the cut-off frequency. Moreover, when SiC was loaded, the remaining impedance was three times lower than when using the copper plate alone. After applying this method to the new septum magnet, the maximum longitudinal impedance was reduced to 1% of the value without countermeasures, largely improving the beam stability condition. We also estimated the required thickness of SiC and the calorific value. This method saves space and is installed by simple attachment to the flange, regardless of the shape of the beam pipe. Therefore, it is also applicable to other devices.

Journal Articles

The Chemistry of thorium, plutonium and MA

Sato, Nobuaki*; Kirishima, Akira*; Watanabe, Masayuki; Sasaki, Takayuki*; Uehara, Akihiro*; Takeda, Shino*; Kitatsuji, Yoshihiro; Otobe, Haruyoshi; Kobayashi, Taishi*

The Chemistry of Thorium, Plutonium and MA, 254 Pages, 2022/03

The chemistry of nuclear materials such as Thorium (Part 1) and Plutonium (Part 2) was described in relation from the fundamentals on solid chemistry and solution chemistry to the practicals on the experiment and evaluation method in detail. Minor actinides such as Neptunium, Americium, Curium and Protoactinium, was introduced the basics on the solid and solution chemistry.

Journal Articles

Nanoscopic structure of borosilicate glass with additives for nuclear waste vitrification

Motokawa, Ryuhei; Kaneko, Koji; Oba, Yojiro; Nagai, Takayuki; Okamoto, Yoshihiro; Kobayashi, Taishi*; Kumada, Takayuki; Heller, W. T.*

Journal of Non-Crystalline Solids, 578, p.121352_1 - 121352_7, 2022/02

 Times Cited Count:0 Percentile:0.01(Materials Science, Ceramics)

Journal Articles

Evaluation and countermeasures for impedance of fast extraction septa and fast extraction kickers at the J-PARC main ring

Kobayashi, Aine*; Toyama, Takeshi*; Nakamura, Takeshi*; Shobuda, Yoshihiro; Ishii, Koji*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.287 - 291, 2021/10

no abstracts in English

Journal Articles

Evaluation by causality for measurement data of longitudinal coupling impedances with stretched-wire method

Toyama, Takeshi*; Kobayashi, Aine*; Shobuda, Yoshihiro

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.666 - 669, 2021/10

no abstracts in English

Journal Articles

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

 Times Cited Count:19 Percentile:98.17(Physics, Multidisciplinary)

A quasifree ($$p$$,$$pn$$) experiment was performed to study the structure of the Borromean nucleus $$^{17}$$B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for $$1s_{1/2}$$ and $$0d_{5/2}$$ orbitals, and a surprisingly small percentage of 9(2)% was determined for $$1s_{1/2}$$. Our finding of such a small $$1s_{1/2}$$ component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in $$^{17}$$B. The present work gives the smallest $$s$$- or $$p$$-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of $$s$$ or $$p$$ orbitals is not a prerequisite for the occurrence of a neutron halo.

Journal Articles

XAFS analysis of ruthenium in simulated iron phosphate radioactive waste glass

Okamoto, Yoshihiro; Kobayashi, Hidekazu; Shiwaku, Hideaki; Sasage, Kenichi; Hatakeyama, Kiyoshi*; Nagai, Takayuki

Journal of Non-Crystalline Solids, 551, p.120393_1 - 120393_8, 2021/01

 Times Cited Count:1 Percentile:31.58(Materials Science, Ceramics)

The chemical state of ruthenium in simulated iron phosphate radioactive waste glass was investigated by conventional X-ray absorption fine structure (XAFS) and imaging XAFS analyses. The EXAFS analysis suggested that ruthenium was contained as glass phase when content of the waste components was less than 10wt.% in 30 mol%Fe$$_{2}$$O$$_{3}$$-P$$_{2}$$O$$_{5}$$ base glass. In other samples, crystalline RuO$$_{2}$$ was predominant. According to the imaging XAFS analysis, RuO$$_{2}$$ particles in all samples had length smaller than 50$$mu$$m. Aggregations of RuO$$_{2}$$, which are found in nuclear waste borosilicate glass, were not seen in any of the iron phosphate glass samples.

Journal Articles

Study of the transverse beam instability caused by the resistive-wall impedance at the J-PARC main ring

Kobayashi, Aine*; Toyama, Takeshi*; Shobuda, Yoshihiro; Nakamura, Takeshi*; Sato, Yoichi*

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.684 - 688, 2020/09

no abstracts in English

Journal Articles

Analysis of collective instabilities of uneven filled beams including long range wake fields using an IIR filter

Toyama, Takeshi*; Kobayashi, Aine*; Nakamura, Takeshi*; Shobuda, Yoshihiro

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.689 - 692, 2020/09

no abstracts in English

Journal Articles

Structural change of borosilicate glass by neutron irradiation

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Akiyama, Daisuke*; Sato, Nobuaki*; Uehara, Akihiro*; Fujii, Toshiyuki*; Sekimoto, Shun*

KURNS Progress Report 2018, P. 105, 2019/08

To understand this structural change of a borosilicate glass by a neutron irradiation in detail, the irradiation test was carried out in KUR in 2017FY. The glass structure was estimated by using Raman spectrometry in 2018FY. Comparing with the Raman spectra of glass samples before and after irradiation, it could be observed the change of peak height of Si-O bridging structure by the irradiation.

JAEA Reports

Synchrotron radiation based XAFS analysis of the simulated nuclear waste glass samples prepared by bottom drain test in the full-scale mock-up melter (KMOC) (Contract research)

Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki; Kano, Shigeru; Himeno, Haruyuki*; Kobayashi, Hiroshi*; Nakatani, Mikio*

JAEA-Research 2018-013, 18 Pages, 2019/03

JAEA-Research-2018-013.pdf:1.98MB

The chemical state and local structure of some elements in the simulated nuclear waste glass samples (20 batches) prepared by bottom drain test in the full scale mock-up tests using KMOC melter were investigated by synchrotron radiation based X-ray absorption fine structure (XAFS) analysis. As a result of the analysis of cerium element, it was confirmed that the oxidation proceeds gently as the batch advanced. For manganese, iron, and zinc, there was almost no difference between batches, which seemed to be stabilized by getting into the frame structure of the borosilicate glass. There were no elements that seemed to be clearly crystalline except for platinum group elements. Remarkable precipitation was hardly observed in zirconium and molybdenum with the imaging analysis.

JAEA Reports

Investigation of simulated waste glass samples prepared from borosilicate glass frit including vanadium

Nagai, Takayuki; Okamoto, Yoshihiro; Shiwaku, Hideaki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Hirono, Kazuya*; Homma, Masanobu*; Kobayashi, Hiromi*; Takahashi, Tomoe*; et al.

JAEA-Research 2018-007, 87 Pages, 2018/11

JAEA-Research-2018-007.pdf:61.21MB

To select the chemical composition of a glass frit which can increase the waste content, the simulated waste glass samples prepared from a borosilicate glass frit including vanadium (V) were investigated by using Laser Ablation (LA) ICP-AES analysis, Raman spectrometry, and synchrotron XAFS measurement in this study on foundation business of the Agency for Natural Resources and Energy.

JAEA Reports

XAFS measurement of simulated waste glass samples prepared from borosilicate glass frit including phosphorus pentaoxide (Joint research)

Nagai, Takayuki; Kobayashi, Hidekazu; Shimamura, Keisuke; Oyama, Koichi; Sasage, Kenichi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamanaka, Keisuke*; Ota, Toshiaki*

JAEA-Research 2018-005, 72 Pages, 2018/09

JAEA-Research-2018-005.pdf:28.2MB

Addition of radioactive waste to a borosilicate glass frit affects the local structures of glass-forming elements and waste elements in a waste glass produced in a vitrification process. In this study, simulated waste glass samples were prepared from borosilicate glass frit including phosphorus pentaoxide, and we investigated local structures of sodium (Na), boron (B), and waste elements in these glass samples by using synchrotron XAFS measurements in soft and hard X ray region.

Journal Articles

Introduction to radiation physics; Third revised edition

Tada, Junichiro*; Nakashima, Hiroshi; Hayano, Ryugo*; Kobayashi, Hitoshi*; Asano, Yoshihiro*

Wakariyasui Hoshasen Butsurigaku; Kaitei 3-Han, 305 Pages, 2018/03

This book is an introduction to radiation physics. Under the concept of "linking physics of high school and radiation physics" for readers with high school graduation degree, we are doing simple commentary on the basis of qualitative explanation as much as possible. This book begins with "What is Radiation Physics", and consists of 12 chapters, including introductory special relativity, introductory quantum theory, structures of atoms and nuclei, radiations, radioactivity, interactions between radiation and matter, accelerators, radiation dose and so on.

Journal Articles

Evaluation of uranium chemical state in borosilicate glasses by using XAFS measurement

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Akiyama, Daisuke*; Sato, Nobuaki*

Photon Factory Activity Report 2017, 2 Pages, 2018/00

no abstracts in English

JAEA Reports

XAFS measurement of simulated waste borosilicate glass samples (Joint research)

Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamanaka, Keisuke*; Ota, Toshiaki*

JAEA-Research 2017-005, 54 Pages, 2017/06

JAEA-Research-2017-005.pdf:16.17MB

Addition of radioactive waste to a borosilicate frit affects the local structures of boron (B) and waste elements in a waste glass. Synchrotron XAFS measurement was applied to investigate the local structural changes by using simulated waste borosilicate glass samples. Following results were obtained by the B K-edge XAFS analysis. It was confirmed that B K-edge XAFS analysis enables us to discriminate sp$$^{2}$$ type boron (BO$$_{3}$$) from sp$$^{3}$$ type boron (BO$$_{4}$$). Addition of waste elements to a glass frit increases the percentage of BO$$_{3}$$ and decreases that of BO$$_{4}$$. By decreasing the SiO$$_{2}$$/Al$$_{2}$$O$$_{3}$$ ratio or increasing the (SiO$$_{2}$$+B$$_{2}$$O$$_{3}$$)/Al$$_{2}$$O$$_{3}$$ ratio in the glass composition, the BO$$_{3}$$ percentage increases and the BO$$_{4}$$ percentage decreases. Addition of P$$_{2}$$O$$_{5}$$ decreases the BO$$_{3}$$ percentage and increases the BO$$_{4}$$ percentage. Following results were obtained from XAFS measurement of the waste elements. Cerium (Ce) valence is more reduced with the increase of the B$$_{2}$$O$$_{3}$$ content. Addition of P$$_{2}$$O$$_{5}$$ has a tendency to reduce the Ce valence and to enhance deposition of Zr oxide. Deposition of ruthenium compounds separated from glass phase can not be improved by changing the B$$_{2}$$O$$_{3}$$ content. This study was performed as a part of the project, "Improvement of vitrification process of high-level radioactive liquid wastes" on the foundation business of the Agency for Natural Resources and Energy.

Journal Articles

Chemical state analysis of high-temperature molten slag components by using high-energy XAFS

Okamoto, Yoshihiro; Osugi, Takeshi; Akabori, Mitsuo; Kobayashi, Toru; Shiwaku, Hideaki

Journal of Molecular Liquids, 232, p.285 - 289, 2017/04

 Times Cited Count:3 Percentile:15.53(Chemistry, Physical)

High energy XAFS measurement using cerium K-edge was performed to study the chemical state of cerium in high-temperature molten slag (SiO$$_{2}$$-CaO-Fe$$_{2}$$O$$_{3}$$-CeO$$_{2}$$). It was found from the change in the nearest Ce-O distance obtained from EXAFS analysis and the energetic shift of the white line peak observed in XANES analysis that oxidation state of cerium was tetravalent in the molten state and trivalent in solid state. The Debye-Waller factor of the nearest Ce-O pair in solid slag was very large even at room temperature, and the change in its value upon heating and melting was very small. This result suggests that cerium is highly disordered and stable in solid slag.

Journal Articles

High temperature Fe-K edge XANES spectrum measurement in preparing iron phosphate glass frit by using hot thermo-couple heating system

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro

Photon Factory Activity Report 2016, 2 Pages, 2017/00

To estimate the valence state of iron in the preparation process of iron phosphate glass frit, mixtures of ferric oxide and phosphoric acid was heated and XANES spectra of Fe-K edge was measured in this study. This report described the situation of high temperature XAFS measurement and results of this study.

JAEA Reports

XAFS measurement of simulated waste glass samples (Borosilicate glass including vanadium)

Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Matsuura, Haruaki*; Uchiyama, Takafumi*; Okada, Yukiko*; Nezu, Atsushi*; et al.

JAEA-Research 2016-015, 52 Pages, 2016/11

JAEA-Research-2016-015.pdf:37.48MB

The local structure of waste elements in simulated waste glasses including V was estimated by using synchrotron XAFS measurement in this study. The results are as follows. (1) V has a high possibility which exists in the glass phase in the case of frit, and V can regard both samples as stable 4 coordination structure. (2) Zn, Ce, Nd, Zr, and Mo exist in the glass phase, and the difference is admitted by the percentage of Ce(III) and Ce(IV) by the composition. (3) Ru is separated from the glass phase as RuO$$_{2}$$ crystalline, both of metal and oxide exist in Rh, and Pd is separated out as metal. (4) It was confirmed that the regularity of the local structure of Zr and Mo in the molten glasses retreats as a result of the XAFS measurement at high temperature. (5) The XAFS measurement of molten glasses were performed at 1200$$^{circ}$$C, so it would be possible to acquire excellent data by improving the shapes of the sample cell.

Journal Articles

Beam commissioning of the linac for iBNCT

Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11

The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.

180 (Records 1-20 displayed on this page)