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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.
