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Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 32 Pages, 2022/02

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Investigation on the DC Stark shifts of strontium autoionization states for isotope-selective resonance ionization

Iwata, Yoshihiro; Miyabe, Masabumi; Hasegawa, Shuichi*

Journal of Quantitative Spectroscopy & Radiative Transfer, 265, p.107549_1 - 107549_7, 2021/05

 Times Cited Count:1 Percentile:0.02(Optics)

Following the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, an isotope-selective analysis method using laser resonance ionization has been developed for strontium-90. In this study, we focused on ionization via autoionization states in terms of high isotopic selectivity and ionization efficiency, and the DC Stark shifts caused by the external electric field were measured for these states. It was found that the external electric field in the ionization region has to be of the order of 0.1 V/cm or less to suppress its effect on the observed spectra.

Journal Articles

Generation of particles and fragments by quasicontinuous wave fiber laser irradiation of stainless steel, alumina, and concrete materials

Daido, Hiroyuki*; Yamada, Tomonori; Furukawa, Hiroyuki*; Ito, Chikara; Miyabe, Masabumi; Shibata, Takuya; Hasegawa, Shuichi*

Journal of Laser Applications, 33(1), p.012001_1 -  012001_16, 2021/02

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Development of laser ablation absorption spectroscopy for nuclear fuel materials; Plume expansion behavior for refractory metals observed by laser-induced fluorescence imaging spectroscopy

Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Kato, Masaaki*; Hasegawa, Shuichi*; Wakaida, Ikuo

Applied Physics A, 126(3), p.213_1 - 213_10, 2020/03

The dynamic behavior of an ablation plume in low pressure rare gas ambient was investigated with laser-induced fluorescence imaging spectroscopy for three refractory metals, i.e. titanium, zirconium and hafnium. A comparison of the plume expansion behaviors for the species of these elements revealed an atomic weight effect on the plume structure formation. A hemispherical thin layer and cavity structure reported previously for gadolinium were observed also for these elements. It was found that the plume size increases as well as the layer thickness decreases with increasing atomic weight. For ground state atoms of Ti, substantial amount of atoms were observed even at the center of the plume. Also, the persistence of the Ti atomic plume was as long as 300 $$mu$$s, which was significantly longer than the other species studied. Furthermore, the mass-dependent elemental separation was observed in the ablation plume produced from a multielement sample. These results suggest that the observed plume structure arises from the ion-electron recombination process and the recoil of the ablated species during the multiple collisions with gas atoms.

Journal Articles

Radiation measurement and analysis

Wakaida, Ikuo; Hasegawa, Shuichi*; Tadokoro, Takahiro*

Nihon Kikai Gakkai-Shi, 122(1211), p.18 - 20, 2019/10

no abstracts in English

Journal Articles

Symposium on "Science of nuclear fuel cycle and backend; Research and education" with a memory of Professor Joonhong Ahn, the University of California, Berkeley

Nakayama, Shinichi; Okumura, Masahiko*; Nagasaki, Shinya*; Enokida, Yoichi*; Umeki, Hiroyuki*; Takase, Hiroyasu*; Kawasaki, Daisuke*; Hasegawa, Shuichi*; Furuta, Kazuo*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(2), p.131 - 148, 2016/12

A symposium "Science of nuclear fuel cycle and backend - Research and education -" was held at the Univer-sity of Tokyo in June 25, 2016. This aimed at developing the research on nuclear fuel cycle and backend. The time and the number of participants of the symposium were limited, but the active discussion was conducted, and the common perception for the future was shared among the experienced participants in those fields. This paper provides the discussions made in the symposium, and also, as a memory to Professor Ahn, the University of California, Berkeley, his prominent achievements in academic research and education.

Journal Articles

Fabrication process qualification of TF Insert Coil using real ITER TF conductor

Ozeki, Hidemasa; Isono, Takaaki; Kawano, Katsumi; Saito, Toru; Kawasaki, Tsutomu; Nishino, Katsumi; Okuno, Kiyoshi; Kido, Shuichi*; Semba, Tomoyuki*; Suzuki, Yozo*; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200804_1 - 4200804_4, 2015/06

 Times Cited Count:0 Percentile:0(Engineering, Electrical & Electronic)

Journal Articles

Graphene growth and carbon diffusion process during vacuum heating on Cu(111)/Al$$_{2}$$O$$_{3}$$ substrates

Ogawa, Shuichi*; Yamada, Takatoshi*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Hasegawa, Masataka*; Teraoka, Yuden; Takakuwa, Yuji*

Japanese Journal of Applied Physics, 52(11), p.110122_1 - 110122_8, 2013/11

 Times Cited Count:17 Percentile:63.5(Physics, Applied)

Journal Articles

Crystal morphology-dependent graft polymerization in poly(ether ether ketone) films

Hasegawa, Shin; Takahashi, Shuichi*; Iwase, Hiroki*; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari

Polymer, 54(12), p.2895 - 2900, 2013/05

 Times Cited Count:9 Percentile:30.77(Polymer Science)

Radiation-induced graft polymerization of sulfo-containing styrene derivatives into crystalline poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer, so-called "super-engineering plastics". Graft polymerization of the sulfo-containing styrene, ethyl 4-styrenesulfonate (E4S) into PEEK substrates with degrees of crystallinity (DC) of 11 - 26% gradually progressed, achieving a grafting degree of more than 50% after 72 hours, whereas graft polymerization of the substrates with DC above 26% did not proceed. When morphological change in these films were measured by SAXS, PEEK films with DC larger than 26% showed a new peak at d=14 nm, corresponding to lamella structure. Thus, the suppression of graft polymerization of PEEK films with DC above 26% was due to obstruct of monomer diffusion by the formation of the oriented lamella structure.

Journal Articles

Vacuum annealing formation of graphene on diamond C(111) surfaces studied by real-time photoelectron spectroscopy

Ogawa, Shuichi*; Yamada, Takatoshi*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Hasegawa, Masataka*; Teraoka, Yuden; Takakuwa, Yuji*

Japanese Journal of Applied Physics, 51(11), p.11PF02_1 - 11PF02_7, 2012/11

 Times Cited Count:23 Percentile:70.04(Physics, Applied)

Journal Articles

Observation of graphene-on-diamond formation studied by real-time photoelectron spectroscopy

Ogawa, Shuichi*; Yamada, Takatoshi*; Ishizuka, Shinji*; Watanabe, Daiki*; Yoshigoe, Akitaka; Hasegawa, Masataka*; Teraoka, Yuden; Takakuwa, Yuji*

Hyomen Kagaku, 33(8), p.449 - 454, 2012/08

Graphene-on-insulator structures are required for fabrication of the graphene transistor. Diamond has been attracted as the substrate for graphene growth because it has a larger band gap and break down voltage compared with SiC. The detail of graphitization on a diamond surface has not been clarified yet because the nondestructive evaluation for graphene-on-diamond (GOD) structure was hard. In this study, we have developed an evaluation method of GOD based on the photoemission spectroscopy using synchrotron radiation focusing the shift of photoelectron spectra due to band bending. We can clearly determine the graphitization temperature on the diamond C(111) surface as approximately 1120 K, which is lower than that on an SiC substrate. It is also confirmed from C 1s photoelectron spectra, there is the buffer layer at the interface between the grapheme layer and the diamond substrate.

Journal Articles

Radiation-induced graft polymerization of functional monomer into poly(ether ether ketone) film and structure-property analysis of the grafted membrane

Hasegawa, Shin; Takahashi, Shuichi*; Iwase, Hiroki*; Koizumi, Satoshi; Morishita, Norio; Sato, Ken*; Narita, Tadashi*; Onuma, Masato*; Maekawa, Yasunari

Polymer, 52(1), p.98 - 106, 2011/01

 Times Cited Count:44 Percentile:82.99(Polymer Science)

Radiation-induced graft polymerization of sulfo-containing styrene derivatives into poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer. Graft polymerization of ethyl 4-styrenesulfonate into a 32% crystallinity degree PEEK substrate hardly progressed, whereas graft polymerization into 11% PEEK substrate gradually progressed, achieving a grafting degree of more than 50% after 72 h. From Electron Spin Resonance analysis of irradiated PEEK films, it apparent the graft polymerization initiate from the phenoxy radicals. Small-angle X-ray scattering and small-angle neutron scattering observations clearly showed that the graft-type PEEK membranes possessed ion channel domains with the average distance of 13 nm, being larger than that of Nafion. Furthermore, there was a micro-structure in the ion channels with the average distance of 1.8 nm.

Journal Articles

Radiation-induced graft polymerization of styrene into a poly(ether ether ketone) film for preparation of polymer electrolyte membranes

Hasegawa, Shin; Sato, Ken*; Narita, Tadashi*; Suzuki, Yasuyuki; Takahashi, Shuichi; Morishita, Norio; Maekawa, Yasunari

Journal of Membrane Science, 345(1-2), p.74 - 80, 2009/12

 Times Cited Count:28 Percentile:69.47(Engineering, Chemical)

Radiation-induced graft polymerization of styrene into poly(ether ether ketone) (PEEK) with 32% crystallinity was investigated with DSC, TGA, XRD, and ESR. Endothermic heats of melting of the original and styrene-grafted PEEK (grafted PEEK) films were similar, indicating the crystallinity was almost completely maintained up to a grafting degree of 51%. Lower glass transition temperature of the grafted PEEK film in the DSC, and the absence of an extra halo originating from amorphous polystyrene grafts in the XRD strongly indicate the grafting of styrene to crystalline PEEK films proceeded in the amorphous region of PEEK. This is probably because polystyrene grafts have hydrocarbon structures similar to a base PEEK polymer, resulting in compatibility to the amorphous phase of the PEEK films. The grafted PEEK films can be converted to PEEK-based electrolyte membranes by subsequent sulfonation, and had conductivity of more than 0.01 S/cm and exhibited higher water content above 100%.

Journal Articles

Enhancement of etch rate for preparation of nano-sized ion-track membranes of poly(vinylidene fluoride); Effect of pretreatment and high-LET beam irradiation

Rohani, R.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Takahashi, Shuichi*; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*

Nuclear Instruments and Methods in Physics Research B, 267(3), p.554 - 559, 2009/08

 Times Cited Count:13 Percentile:68.24(Instruments & Instrumentation)

We investigated how pretreatment and high-LET beam irradiation affected the ion-track dissolution rate in poly(vinylidene fluoride) (PVDF) films by SEM observations and conductometric analysis in order to develop the preparation methodology of nano-sized ion-track membranes. PVDF thin films irradiated with four types of ion beams were exposed to a 9 M KOH aqueous solution after their storage in air at 120$$^{circ}$$C. This heating treatment was found to enhance the etch rate in the latent track, both in the inner core and outer halo regions, without changing that in the bulk, probably due to the formation of parasitic oxidation products facilitating the introduction of the etching agent to improve the etchability. Additionally, the irradiation of heavier higher-LET ions, causing each track to more activated sites (like radicals), was preferable for achieving effective etching.

Journal Articles

Etching behavior of poly(vinylidene fluoride) thin films irradiated with ion beams; Effect of irradiated ions and pretreatment

Yamaki, Tetsuya; Rohani, R.*; Koshikawa, Hiroshi; Takahashi, Shuichi; Hasegawa, Shin; Asano, Masaharu; Voss, K.-O.*; Neumann, R.*; Maekawa, Yasunari

Kobunshi Rombunshu, 65(3), p.273 - 276, 2008/03

 Times Cited Count:3 Percentile:11.89(Polymer Science)

Poly(vinylidene fluoride) thin films irradiated with four kinds of ion beams were exposed to a 9 M KOH aqueous solution after their storage in air for 30 or 90 days at different temperatures. According to the conductometry, the heating at 120ºC was found to enhance the etch rate in the latent track without changing that in the bulk, thereby enabling us to obtain very high etching sensitivity for the preparation of nano-sized through-pores. The formation of hydroperoxides during this pretreatment should facilitate the introduction of the etching agent to improve etchability. Additionally, the irradiation of higher-LET ions, causing each track to more activated sites (like radicals), was preferable to achieve high sensitivity of the etching.

Journal Articles

Status of a superconducting linac for the J-PARC ADS

Hasegawa, Kazuo; Ouchi, Nobuo; Chishiro, Etsuji; Kako, Eiji*; Noguchi, Shuichi*; Ouchi, Norihito*; Shishido, Toshio*; Tsuchiya, Kiyosumi*

Proceedings of 34th ICFA Advanced Beam Dynamics Workshop on High Power Superconducting Ion, Proton and Multi-Species Linacs (HPSL 2005) (Internet), 5 Pages, 2005/00

no abstracts in English

Journal Articles

Chemical studies on rutherfordium (Rf) at JAERI

Nagame, Yuichiro; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Ishii, Yasuo; Sato, Tetsuya; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; et al.

Radiochimica Acta, 93(9-10), p.519 - 526, 2005/00

 Times Cited Count:29 Percentile:88.24(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Cold-model tests and fabrication status for J-PARC ACS

Ao, Hiroyuki; Akikawa, Hisashi; Ueno, Akira; Hasegawa, Kazuo; Yamazaki, Yoshishige; Ikegami, Masanori*; Noguchi, Shuichi*; Hayashizaki, Noriyosu*; Paramonov, V.*

Proceedings of 22nd International Linear Accelerator Conference (LINAC 2004), p.75 - 77, 2004/00

The J-PARC (Japan Proton Accelerator Research Complex) LINAC will be commissioned with energy of 181-MeV using 50-keV ion source, 3-MeV RFQ, 50-MeV DTL and 181-MeV SDTL (Separated DTL) on September 2006. It is planed to be upgraded by using a 400-MeV ACS (Annular Coupled Structure), which is a high-beta structure most suitable for the J-PARC, in a few years from the commissioning. The first ACS type cavity, which will be used as the first buncher between the SDTL and the ACS, is under fabrication. Detailed design and tuning procedure of ACS cavities has been studied with RF simulation analysis and cold-model measurements. The results of cold-model measurements, fabrication status, and related development items are described in this paper.

Journal Articles

R&D status of superconducting proton linear accelerator for ADS at JAERI

Ouchi, Nobuo; Akaoka, Nobuo*; Asano, Hiroyuki*; Chishiro, Etsuji; Hasegawa, Kazuo; Takeda, Osamu; Yoshikawa, Hiroshi; Matsuoka, Masanori*; Otani, Toshihiro*; Kako, Eiji*; et al.

Proceedings of 11th International Conference on Nuclear Engineering (ICONE-11) (CD-ROM), 6 Pages, 2003/04

no abstracts in English

Journal Articles

Cold test of 600MHz superconducting cryomodule for high intensity proton linac

Ouchi, Nobuo; Akaoka, Nobuo*; Asano, Hiroyuki*; Chishiro, Etsuji; Hasegawa, Kazuo; Takeda, Osamu*; Yoshikawa, Hiroshi; Matsuoka, Masanori*; Otani, Toshihiro*; Kako, Eiji*; et al.

Proceedings of 21st International Linear Accelerator Conference, p.488 - 490, 2003/00

Development of a superconducting proton linac is in progress in collaboration with KEK. In order to demonstrate cavity performance and to study stable accelerating field in a pulsed operation, a 600MHz superconducting cryomodule has been fabricated. The cryomodule includes two 5-cell superconducting cavities of $$beta$$=0.6 and is designed to perform 2K operation. Cold tests of the cryomodule have been performed at the temperature of 4K and 2K. In the tests, heat leak to the cavities, loaded quality factors, tuning sensitivities, frequency shifts against helium vessel pressure and Lorentz force detuning of the cavities were measured. Most of the measured data agreed with their design values, except for the heat leak and the Lorentz force detuning. As the preliminary horizontal test of the cryomodule, high power RF test has been also performed, where the surface peak fields of 10 and 16 MV/m were achieved in CW and pulsed operation, respectively. Now, the optimization of the RF control system is in progress to demonstrate stable accelerating field in a pulsed operation.

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