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Journal Articles

Progress of the spoke cavity prototyping for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Domae, Takeshi*

Proceedings of 32nd Linear Accelerator Conference (LINAC 2024) (Internet), p.496 - 498, 2024/10

Journal Articles

Fabrication progress of the prototype spoke cavity for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Domae, Takeshi*

Journal of Physics; Conference Series, 2687(5), p.052008_1 - 052008_6, 2024/01

 Times Cited Count:0

Journal Articles

Measurement of double-differential neutron yields for iron, lead, and bismuth induced by 107-MeV protons for research and development of accelerator-driven systems

Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.

EPJ Web of Conferences, 284, p.01023_1 - 01023_4, 2023/05

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron, lead, and bismuth have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics. The measured TTNYs and DDXs were compared with calculations by the Monte Carlo transport code PHITS with its default physics model of INCL version 4.6 combined with GEM and those with the JENDL-4.0/HE nuclear data library.

Journal Articles

Measurement of 107-MeV proton-induced double-differential thick target neutron yields for Fe, Pb, and Bi using a fixed-field alternating gradient accelerator at Kyoto University

Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.

Journal of Nuclear Science and Technology, 60(4), p.435 - 449, 2023/04

 Times Cited Count:3 Percentile:52.93(Nuclear Science & Technology)

Double-differential thick target neutron yields (TTNYs) for Fe, Pb, and Bi targets induced by 107-MeV protons were measured using the fixed-field alternating gradient accelerator at Kyoto University for research and development of accelerator-driven systems (ADSs) and fundamental ADS reactor physics research at the Kyoto University Critical Assembly (KUCA). Note that TTNYs were obtained with the time-of-flight method using a neutron detector system comprising eight neutron detectors; each detector has a small NE213 liquid organic scintillator and photomultiplier tube. The TTNYs obtained were compared with calculation results using Monte Carlo-based spallation models (i.e., INCL4.6/GEM, Bertini/GEM, JQMD/GEM, and JQMD/SMM/GEM) and the evaluated high-energy nuclear data library, i.e., JENDL-4.0/HE, implemented in the particle and heavy iontransport code system (PHITS). All models, including JENDL-4.0/HE, failed to predict high-energy peaks at a detector angle of 5$$^{circ}$$. Comparing the energy- and angle-integrated spallation neutron yields at energies of $$le$$20 MeV estimated using the measured TTNYs and the PHITS indicated that INCL4.6/GEM would be suitable for the Monte Carlo transport simulation of ADS reactor physics experiments at the KUCA.

Journal Articles

Measurement of 107-MeV proton-induced double-differential neutron yields for iron for research and development of accelerator-driven systems

Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; Yashima, Hiroshi*; Nishio, Katsuhisa; et al.

JAEA-Conf 2022-001, p.129 - 133, 2022/11

For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors composed of the NE213 liquid organic scintillators and photomultiplier tubes, which were connected to a multi-channel digitizer mounted with a field-programmable gate array (FPGA), for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination applying the gate integration method to the FPGA. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics.

Journal Articles

Current status of the spoke cavity prototyping for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Domae, Takeshi*

Proceedings of 31st International Linear Accelerator Conference (LINAC 2022) (Internet), p.180 - 183, 2022/09

The Japan Atomic Energy Agency (JAEA) has proposed an accelerator-driven subcritical system (ADS) to efficiently reduce high-level radioactive waste generated at nuclear power plants. One of the challenging R&D aspects of ADS is the reliability of the accelerator. In preparation for the full-scale design of the CW proton linac for the JAEA-ADS, we are now prototyping a low-beta (around 0.2) single spoke cavity. Since there is no experience in Japan in manufacturing a superconducting spoke cavity, prototyping and performance testing of the cavity is essential to ensure the feasibility of the JAEA-ADS linac. In the Japanese fiscal year 2021, we have started welding cavity parts together. By preliminarily examining the electron beam welding conditions, each press-formed niobium part was joined with a smooth welding bead. At present, we have fabricated the cavity's body part.

Journal Articles

Skyrmion creation and annihilation by electric current vorticity

Fujimoto, Junji*; Funaki, Hiroshi*; Koshibae, Wataru*; Matsuo, Mamoru; Maekawa, Sadamichi*

IEEE Transactions on Magnetics, 58(8), p.1500407_1 - 1500407_7, 2022/08

 Times Cited Count:1 Percentile:0.00(Engineering, Electrical & Electronic)

Journal Articles

Present status of the spoke cavity prototyping for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Yee-Rendon, B.; Domae, Takeshi*; Kako, Eiji*; Sakai, Hiroshi*; Umemori, Kensei*

Proceedings of 20th International Conference on RF Superconductivity (SRF 2021) (Internet), p.612 - 615, 2021/06

Journal Articles

RF design of the prototype spoke cavity for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Hasegawa, Kazuo; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Konomi, Taro*

JPS Conference Proceedings (Internet), 33, p.011049_1 - 011049_6, 2021/03

Journal Articles

Electromagnetic design of the prototype spoke cavity for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Hasegawa, Kazuo; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Konomi, Taro*

Proceedings of 19th International Conference on RF Superconductivity (SRF 2019) (Internet), p.399 - 402, 2019/11

Journal Articles

Optically transparent ferromagnetic nanogranular films with tunable transmittance

Kobayashi, Nobukiyo*; Masumoto, Hiroshi*; Takahashi, Saburo*; Maekawa, Sadamichi

Scientific Reports (Internet), 6, p.34227_1 - 34227_7, 2016/09

 Times Cited Count:33 Percentile:75.18(Multidisciplinary Sciences)

Journal Articles

Ion-track grafting of vinylbenzyl chloride into poly(ethylene-$$co$$-tetrafluoroethylene) films using different media

Nuryanthi, N.*; Yamaki, Tetsuya; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Suzuki, Akihiro*; et al.

Transactions of the Materials Research Society of Japan, 40(4), p.359 - 362, 2015/12

The ion-track grafting of a vinylbenzyl chloride (VBC) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film is necessary for preparing nanostructured hydroxide-ion-conductive electrolyte membranes. A key for success here is to obtain as high graft levels as possible (for higher conductivity) in a smaller number of tracks (for improving the other membrane properties). To this end, therefore, the effect of the medium for the VBC grafting was investigated as part of our continuing effort to optimize the experimental conditions. A 25 $$mu$$m-thick ETFE film was irradiated in a vacuum chamber with 560 MeV $$^{129}$$Xe at different fluences, and then the grafting was performed by immersing the irradiated films in a 20vol% VBC monomer at 60$$^{circ}$$C. A medium was a mixture of water (H$$_{2}$$O) and isopropyl alcohol (iPrOH) at different volume ratios. The degree of grafting increased as the H$$_{2}$$O content became higher, and reached a maximum in pure H$$_{2}$$O. These results can be explained by considering the well-known Trommsdorff effect, in which poor solubility of the grafted polymer in polar media leads to an increased polymerization rate probably due to a lower termination rate.

Journal Articles

Poly(ether ether ketone) (PEEK)-based graft-type polymer electrolyte membranes having high crystallinity for high conducting and mechanical properties under various humidified conditions

Hamada, Takashi; Hasegawa, Shin; Fukasawa, Hideyuki*; Sawada, Shinichi; Koshikawa, Hiroshi; Miyashita, Atsumi; Maekawa, Yasunari

Journal of Materials Chemistry A, 3(42), p.20983 - 20991, 2015/11

 Times Cited Count:36 Percentile:70.80(Chemistry, Physical)

no abstracts in English

Journal Articles

Fabrication of hard-coated optical absorbers with microstructured surfaces using etched ion tracks; Toward broadband ultra-low reflectance

Amemiya, Kuniaki*; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Shitomi, Hiroshi*; Numata, Takayuki*; Kinoshita, Kenichi*; Tanabe, Minoru*; Fukuda, Daiji*

Nuclear Instruments and Methods in Physics Research B, 356-357, p.154 - 159, 2015/08

 Times Cited Count:10 Percentile:62.42(Instruments & Instrumentation)

Broadband low reflectance materials have various applications in the field of optical energy management; however, materials with ultra-low reflectance (below 0.1%) have been considered as mechanically delicate. We have developed a novel hard-surface optical absorber with microstructured, diamond-like carbon coated ion tracks on CR-39 plastic substrate. The spectral reflectance of the first prototype was below 2% for wavelengths ranging from 400 nm to 1400 nm; moreover, the optical absorber had mechanically hard surface and exhibited temporal durability. Choosing the appropriate design of the surface structure and coating layer is likely to reduce the reflectance to the order of 0.1%. This technique yields easy-to-handle broadband ultra-low reflectance absorbers.

JAEA Reports

Preliminary examination about the seal leak using the photocoagulation resin (Joint research)

Ooka, Makoto; Maekawa, Yasunari; Tomizuka, Chiaki; Murakami, Tomoyuki*; Katagiri, Genichi*; Ozaki, Hiroshi*; Kawamura, Hiroshi

JAEA-Technology 2015-003, 31 Pages, 2015/03

JAEA-Technology-2015-003.pdf:3.95MB

An action for the decommissioning of the Fukushima Daiichi Nuclear Power Station (Tokyo Electric Power Company) is pushed forward now. For fuel debris Remove, it is necessary to fill the Primary Containment Vessel (PCV) with water. Because a coolant leaks out from the PCV, it becomes the most important problem to seal leak the coolant. Nuclear Plant Decommissioning Safety Research Establishment has examined the method of seal leak using the photocoagulation resin. However, originally the photocoagulation resin is used as coating or the painting, and the applicability to seal leak water is unknown. This report describes the result that examined the applicability to seal leak using photocoagulation resin.

Journal Articles

R&D of invar duct for fabrication of 2nd JSNS moderators

Harada, Masahide; Teshigawara, Makoto; Maekawa, Fujio; Oi, Motoki; Kasugai, Yoshimi; Takada, Hiroshi

Journal of Nuclear Materials, 450(1-3), p.104 - 109, 2014/07

 Times Cited Count:3 Percentile:22.94(Materials Science, Multidisciplinary)

Japan Spallation Neutron Source (JSNS) in Japan Proton Accelerator Research Complex (J-PARC) has three super-critical hydrogen moderators. The moderator piping has a multilayer structure; a cryogenic layer, a vacuum layer, a helium layer and a cooling water layer. Through the fabrication of the current (1st) moderators, we learned that thermal shrinkage between room temperature (R.T.) and cryogenic temperature at the cryogenic layer made the fabrication process very difficult. Therefore, for the spare (2nd) moderators, we proposed to use a low thermal shrinkage material, Invar, as a piping material. However, there were items to be solved for realizing the Invar duct inview of the fabrication. In this presentation, we report results of (1) Bending test, (2) Welding test and (3) Dissimilar joint test on the Invar duct. (1) In the bending test, the Invar ducts of 22 mm in diameter and 1.5 mm in thickness were tried to be bent into an elbow with 40 mm in radius. By pre-cooling the duct in the liquid nitrogen followed by the bending with slow speed (1 minute), the duct could be bent without any cracks. (2) Through some welding testes by TIG-welding, the proper groove geometry was determined. (3) For the dissimilar joint test, tensile specimens including a bonding region having size of 4 or 6 mm in diameter at the smallest part and 60 mm in length were cut from three rods made by Invar-A6061 and Invar-SS316L, respectively. Those rods were bonded by the friction welding. All specimens were examined at two temperatures, R.T. and 77 K (liquid nitrogen temperature), resulting that 0.2% proof stresses corresponding to the bonding strengths were larger than those of base materials for both the Invar-A6061 and the Invar-SS316L cases. The present result indicates that the Invar duct is available for the 2nd moderators.

Journal Articles

Giant dielectric and magnetoelectric responses in insulating nanogranular films at room temperature

Kobayashi, Nobukiyo*; Masumoto, Hiroshi*; Takahashi, Saburo*; Maekawa, Sadamichi

Nature Communications (Internet), 5, p.4417_1 - 4417_6, 2014/07

 Times Cited Count:57 Percentile:88.06(Multidisciplinary Sciences)

The electric and magnetic properties of matter are of great interest for materials science and their use in electronic applications. Large dielectric and magnetoelectric responses of materials at room temperature are a great advantage for electromagnetic device applications. Here we present a study of FeCo-MgF nanogranular films exhibiting giant dielectric and magnetoelectric responses at room temperature; with dielectric constant $$varepsilon$$'=490 and magnetoelectric response $$Delta$$$$varepsilon$$'/$$varepsilon$$'$$_{0}$$=3%. In these films, Fe-Co alloy-based nanometer-sized magnetic granules are dispersed in a Mg-fluoride-based insulator matrix. Insulating nanogranular films are a new class of multifunctional materials. The giant responses are caused by spin-dependent charge oscillation between magnetic granules via quantum-mechanical tunnelling. A possible application of such insulating nanogranular materials with giant response is in the construction of a tunable device, in which impedance components such as capacitance and inductance are tunable at room temperature.

Journal Articles

Observation of Barnett fields in solids by nuclear magnetic resonance

Chudo, Hiroyuki; Ono, Masao; Harii, Kazuya; Matsuo, Mamoru; Ieda, Junichi; Haruki, Rie*; Okayasu, Satoru; Maekawa, Sadamichi; Yasuoka, Hiroshi; Saito, Eiji

Applied Physics Express, 7(6), p.063004_1 - 063004_4, 2014/06

 Times Cited Count:46 Percentile:84.37(Physics, Applied)

A magnetic field is predicted to emerge on a particle in a rotating body even if the body is electrically neutral. This emergent field is called a Barnett field. We show that nuclear magnetic resonance (NMR) enables direct measurement of the Barnett field in solids. We rotated both a sample and an NMR coil synchronously at high speed and found an NMR shift whose sing reflects that of the nuclear magnetic moments. This result provides direct evidence of the Barnett field. The use of NMR for Barnett field measurement enables the unknown signs of nuclear magnetic moments in solids to be determined.

Journal Articles

Imidazolium cation based anion-conducting electrolyte membranes prepared by radiation induced grafting for direct hydrazine hydrate fuel cells

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Journal of the Electrochemical Society, 161(9), p.F889 - F893, 2014/06

 Times Cited Count:21 Percentile:59.80(Electrochemistry)

Graft-type anion-conducting electrolyte membranes (AEMs) with imidazolium cations on graft polymers were synthesized through radiation-induced graft polymerization of ${it N}$-vinylimidazole (NVIm) on poly(ethylene-co-tetrafluoroethylene) (ETFE) films, followed by ${it N}$-propylation and ion-exchange reactions. The ${it N}$-propylation proceeded quantitatively, whereas the ion-exchange reactions in 1 M KOH at 60$$^{circ}$$C were accompanied by partial $$beta$$-elimination of the imidazolium cations(AEM2), which exhibited an ion-exchange capacity (IEC) of 0.85 mmol g$$^{-1}$$ and ionic conductivity of 10 mS cm$$^{-1}$$. AEM2 showed alkaline stability at 60$$^{circ}$$C but it gradually degraded at 80$$^{circ}$$C for ca. 150 h. The copolymer-type AEM (AEM3) with an IEC of 1.20 mmol g$$^{-1}$$ was prepared through the copolymerization of NVIm with styrene on ETFE films, followed by the same ${it N}$-propylation and ion-exchange reactions. AEM3 was shown higher alkaline durability in 1 M KOH at 80$$^{circ}$$C. As a result, it exhibited higher conductivity ($$>$$10 mS cm$$^{-1}$$) for 250 h. Therefore, alkylimidazolium cations in copolymer grafts are a promising anion conducting group for alkaline-durable AEMs. A maximum power density of 75 mW cm$$^{-2}$$ is obtained for AEM3 in a direct hydrazine hydrate fuel cell.

Journal Articles

Effect of anisotropic spin absorption on the Hanle effect in lateral spin valves

Izuchi, Hiroshi*; Fukuma, Yasuhiro*; Takahashi, Saburo*; Maekawa, Sadamichi; Otani, Yoshichika*

Physical Review B, 89(8), p.081308_1 - 081308_5, 2014/02

 Times Cited Count:25 Percentile:69.13(Materials Science, Multidisciplinary)

341 (Records 1-20 displayed on this page)