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Yamakawa, Koki*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Transactions of 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
no abstracts in English
Nishida, Akemi; Kawata, Manabu; Choi, B.; Kunitomo, Takahiro; Shiomi, Tadahiko; Iigaki, Kazuhiko; Yamakawa, Koki*
Transactions of 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
no abstracts in English
Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*
Transactions of 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 8 Pages, 2024/03
no abstracts in English
formation pathways in molecular clouds; Ultraviolet photolysis of CO-HO iceHirayama, Akemi*; Arakawa, Ichiro*; Yamakawa, Koichiro
Astrophysical Journal, 951(2), p.132_1 - 132_12, 2023/07
Times Cited Count：0 Percentile：0(Astronomy & Astrophysics)With use of reflection-absorption infrared spectroscopy, we investigated the binary ice of CO and HO at 10 K under ultraviolet irradiation as an analogue of interstellar ice mantle. We employed H
O instead of H
O to distinguish the formation pathways of CO, and prepared mixed-ice samples under CO- and HO-rich conditions as well as bilayered one, where CO was condensed on HO ice. After the ultraviolet irradiation onto any sample, we detected infrared absorption bands of CO and COO, which were generated through the CO-CO and CO-HO reactions, respectively. We analyzed the irradiation-time dependence of the CO and COO column densities in CO-rich ice to determine the effective cross sections of the CO formation through the CO-CO and CO-HO reactions simultaneously.
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08
Several large-scale earthquakes have occurred, such as the Niigataken Chuetsu-oki Earthquake in 2007 and the 2011 off-the-Pacific coast of Tohoku Earthquake. Therefore, a three-dimensional (3D) finite element model to evaluate the local response of the reactor building is currently being developed for seismic response analysis. In order to refine the 3D finite element model, it is important to verify the correspondence to the seismic observation behaviors. In this study, the authors analyze the basic response characteristics, such as the natural frequencies and modes of the reactor building, and evaluate the effects of the amplitude of the seismic excitation on the response characteristics based on seismic observation records. This is done to clarify the behavior of a reactor building during earthquakes. These analyses will assist in quantitatively evaluating the correlation between the natural frequency of the building and the amplitude of the seismic excitation. Furthermore, the ratios of rotational displacement and displacement caused by building deformation for natural modes are discussed.
Yamamoto, Kazami; Yamakawa, Emi*; Takayanagi, Tomohiro; Miki, Nobuharu*; Kamiya, Junichiro; Saha, P. K.; Yoshimoto, Masahiro; Yanagibashi, Toru*; Horino, Koki*; Nakanoya, Takamitsu; et al.
ANS RPSD 2018; 20th Topical Meeting of the Radiation Protection and Shielding Division of ANS (CD-ROM), 9 Pages, 2018/08
The existing beam power of the J-PARC Rapid Cycling Synchrotron is up to 500 kW, and higher radiation doses are concentrated in the injection area. These activations are caused by the interaction between the foil and the beam. To reduce dose exposure to workers near the injection point, we study a new design of the injection scheme. Experience has shown that eddy currents are generated in the metal flange near the magnet owing to the pulsed magnetic field, and the temperature exceeds 100 degrees C. The shield installed in the new injection system needs to have a layer structure, in which an insulator is inserted between iron shields to reduce the eddy current. From the results of the shielding calculation, even if 1 mm of polyethylene was inserted between two 9-mm-thick SUS 316 plates, which serve as shielding material, the shielding performance was reduced only about 5%, and we confirmed that it would function well.
Yoshimoto, Masahiro; Yamakawa, Emi*; Takeda, Osamu; Yamamoto, Kazami; Harada, Hiroyuki; Saha, P. K.; Okabe, Kota; Kinsho, Michikazu
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.938 - 943, 2015/09
In the 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), we adopted the multi-turn charge exchange injection scheme using the stripper foils to achieve the high power proton beam. Therefore it is difficult to suppress the interaction between the stripper foils and the beam theoretically. And then, there are high residual dose around the stripper foil. From the measurements of the residual dose distribution and simulations using the PHITS, it is identified that secondary particles produced in the nuclear reactions with the foil had caused the high residual activity around there. And then, it was clear that the beam loss caused by the H
particles which were converted from the injected H
particles by the residual-gas stripping generates the localized high peak residual dose. In this presentation, we report the current status and the cause of the residual dose at the injection area in the RCS.
Yoshimoto, Masahiro; Yamakawa, Emi*; Takeda, Osamu; Yamamoto, Kazami; Harada, Hiroyuki; Saha, P. K.; Okabe, Kota; Kinsho, Michikazu
no journal, ,
In the 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), we adopted the multi-turn charge exchange injection scheme using the stripper foils to achieve the high power proton beam. This injection scheme has the advantage of injecting the beam without limitation in number of bunched beam and without the beam loss in principle. Therefore it is adopted in the world high intensity proton beam accelerators. However, recent beam studies in the RCS make clear that this injection scheme causes the high radio activation around the stripper foil in spite of the reduction in the injection beam loss. In this presentation, we report the current status and the cause of the residual dose at the injection area in the RCS.
Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*
no journal, ,
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Moritani, Hiroshi*; Yamakawa, Koki*; Saruta, Masaaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Kawata, Manabu; Nishida, Akemi; Choi, B.; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
Nishida, Akemi; Kawata, Manabu; Choi, B.; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
Hirayama, Akemi*; Arakawa, Ichiro*; Yamakawa, Koichiro
no journal, ,
Molecular clouds are composed of gases and interstellar dust. The dust is covered with an ice mantle containing a variety of molecules such as HO and CO and is exposed to ultraviolet radiation. In the present study, we investigated the photochemical reaction in the ice mantle utilizing isotopologues.
Tsuchiya, Takashi*; Yamakawa, Koki*; Saruta, Masaaki*; Iiba, Masanori*; Hiramatsu, Masako*; Nishida, Akemi; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Yamakawa, Koki*; Tsuchiya, Takashi*; Hiramatsu, Masako*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Shiomi, Tadahiko; Nishida, Akemi; Choi, B.; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*
no journal, ,
no abstracts in English
