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

https://doi.org/10.1088/1742-6596/2687/5/052008

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

https://doi.org/10.1051/epjconf/202328401023

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.

Experimental study of nuclear data for Accelerator-Driven Transmutation System (ADS) using Kyoto University FFAG accelerator

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

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.404 - 409, 2023/01

https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TUP0/TUP040.pdf

no abstracts in English

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

https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE14

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.

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

https://doi.org/10.18429/JACoW-SRF2021-WEPCAV011

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

https://doi.org/10.18429/JACoW-SRF2019-TUP007

Ion-track grafting of vinylbenzyl chloride into poly(ethylene--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

http://doi.org/10.14723/tmrsj.40.359

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 m-thick ETFE film was irradiated in a vacuum chamber with 560 MeV Xe at different fluences, and then the grafting was performed by immersing the irradiated films in a 20vol% VBC monomer at 60C. A medium was a mixture of water (HO) and isopropyl alcohol (iPrOH) at different volume ratios. The degree of grafting increased as the HO content became higher, and reached a maximum in pure HO. 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.

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

https://doi.org/10.1016/j.nimb.2015.05.002

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.

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

https://doi.org/10.1016/j.jnucmat.2013.11.017

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.

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

https://doi.org/10.7567/APEX.7.063004

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.