Author: Imao, H.
Paper Title Page
MOPRI082 Acceleration of High-Intensity Heavy-Ion Beams at RIKEN RI Beam Factory 800
 
  • O. Kamigaito, T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, T. Nakagawa, M. Nakamura, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa
    RIKEN Nishina Center, Wako, Japan
  • T. Nagatomo
    RIKEN, Saitama, Japan
 
  Recent efforts concerning the RIBF accelerators in RIKEN have been directed towards achieving higher beam intensities of very heavy ions such as uranium and xenon. As presented in the last IPAC conference in 2013, the intensities of these ion beams have significantly improved due to the construction of a new injector, RILAC2, which is equipped with a 28-GHz superconducting ECR ion source, the development of a helium gas stripper, and upgrading of the bending power of the fRC. In this light, this paper presents the subsequent upgrade programs carried out in the last couple of years, such as developments of a new air stripper for xenon beams and a micro-oven for metallic ions. The current performance level of the RIBF accelerator complex, as well as a future plan to further increase the beam intensities, are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI082  
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THPME136 Beam Energy and Longitudinal Beam Profile Measurement System at RIBF 3566
 
  • T. Watanabe, M. Fujimaki, N. Fukunishi, H. Imao, O. Kamigaito, M. Kase, M. Komiyama, N. Sakamoto, K. Suda, M. Wakasugi, K. Yamada
    RIKEN Nishina Center, Wako, Japan
 
  Monitors that use plastic scintillator (scintillation monitors) were fabricated to measure the energy and longitudinal profiles of heavy-ion beams at the RIKEN RI beam factory (RIBF).Six pairs of scintillation monitors (12 monitors) installed in the transport lines were used to measure the particle time-of-flight (TOF) to determine the acceleration energy of the heavy-ion beams. In addition, five scintillation monitors were installed to optimize the phase between the rebuncher cavities and the beam for the beam injection to the cyclotrons. Longitudinal beam profiles were obtained by using a time-to-digital converter (TDC), which digitizes the detected signals from the scintillator and the RF clock. The energy of the beam can be calculated from the measured TOF of the beam by using a scintillation monitor pair. Recently, to help users operate the system more easily, a new embedded processor with a higher-performance CPU was introduced, and LabVIEW programs were newly written or greatly improved. Development of the scintillation monitor system and results of experimental measurements of heavy-ion beams are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME136  
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THPME067 Air Stripper for Intense Heavy Ion Beams 3388
 
  • H. Imao
    RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
  • M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, H. Okuno, Y. Yano
    RIKEN Nishina Center, Wako, Japan
 
  Intensity upgrade of very heavy ions such as uranium or xenon 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 beams was a principal bottleneck for the intensity upgrade. We have already developed and successfully operated a re-circulating He-gas stripper for 10-MeV/u uranium beams as an alternative to carbon foils. Recently, the 2nd gas stripper with air dedicated for 50-MeV/u 124Xe beams was developed. The differential pumping techniques similar to that used in the He gas stripper was applied. We confined a very thick gas target, up to 20~mg/cm2 of air, in a 0.5-m target chamber. One good feature of using air is that it can be inexhaustible for our use. The stripper was stably operated in user runs performed in June 2013. The service rate reached 91\%. The maximum beam intensity reached 38~pnA and the average intensity provided to users becomes approximately four times higher than it was in 2012. The down-time free gas strippers greatly contributed to these improvements. We also discuss the applicability of the air stripper to 50-MeV/u 238U beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME067  
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