Author: Okuno, H.
Paper Title Page
MO1PB01 Acceleration of Intense Heavy Ion Beams in RIBF Cascaded-Cyclotrons 1
  • N. Fukunishi, T. Dantsuka, M. Fujimaki, T. Fujinawa, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, T. Kageyama, O. Kamigaito, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, M. Nakamura, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa
    RIKEN Nishina Center, Wako, Japan
  The RIBF cascaded-cyclotrons have obtained, as of December 2012, uranium ion beams with an intensity of as high as 15 pnA (1 kW of power). This was achieved owing to deployment of a 28 GHz ECRIS, a new injector linac, a gas stripper and a bending-power upgrade of RIKEN fixed-frequency Ring Cyclotron as well as improvement of transmission efficiencies through cyclotrons and stability, etc.   
slides icon Slides MO1PB01 [12.793 MB]  
MOPPT022 Design of New Superconducting Ring Cyclotron for the RIBF 79
  • J. Ohnishi, M. Nakamura, H. Okuno
    RIKEN Nishina Center, Wako, Japan
  At the RIBF, uranium beams are accelerated up to the energy of 345 MeV per nucleon with a RFQ linac, DTL, and four ring cyclotrons (RRC, fRC, IRC, SRC). However, the present beam current of the uranium is 10-15 pnA at the exit of the SRC, still low, because we have to use two charge strippers located upstream and downstream of the fRC to convert the U35+ ions extraced from the 28 GHz ECR ion source to U64+ and U86+, respectively. Accordingly, in order to increase the beam current more than tenfold, we performed the design study of the new superconducting ring cyclotron with the K-value of 2200 which can accelerate the U35+ ions from 11 MeV/u to 48 MeV/u without the first charge stripper. The number of sector magnets is four and the RF frequency is fixed. The maximum magnetic field strength on the beam orbit is 3.2 T, and the superconducting main coils of the dense winding of NbTi and the trim coils of normal-conducting Cu are used. The total weight of the iron yokes is approximately 4800 t. This paper also describes the beam injection and extraction system which includes one superconducting magnetic channel.  
TU3PB03 R&D of Helium Gas Stripper for Intense Uranium Beams 265
  • H. Imao, T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, K. Kumagai, T. Maie, H. Okuno, T. Watanabe, Y. Watanabe, K. Yamada, Y. Yano
    RIKEN Nishina Center, Wako, Japan
  Intensity upgrade of uranium beams is one of the main concerns at the RIKEN Radioactive Isotope Beam Factory (RIBF). The lifetime problem of carbon-foil strippers due to the high energy loss of uranium beams around 10~MeV/u was a principal bottleneck for the intensity upgrade in the acceleration scheme at the RIBF. We have developed a re-circulating He-gas stripper as an alternative to carbon foils for the acceleration of high-power uranium beams. The new stripping system was actually operated in user runs with U35+ beams of more than 1 puA. Electron-stripped U64+ beams were stably delivered to subsequent accelerators without serious deterioration of the system for six weeks. The new He-gas stripper, which removed the primary bottleneck in the high-intensity uranium acceleration, greatly contributed the tenfold increase of the average output intensity of the uranium beams from the previous year.  
slides icon Slides TU3PB03 [11.983 MB]