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Hemmi, M.

Paper Title Page
TUPC052 Beam Phase and RF Fields Monitoring System Using Lock-In Amplifier for RIBF 1173
 
  • R. Koyama, M. K. Fujimaki, N. Fukunishi, M. Hemmi, O. Kamigaito, M. Kase, Y. Kotaka, N. S. Sakamoto, K. Suda, T. Watanabe, K. Yamada, Y. Yano
    RIKEN, Saitama
 
  The accelerator complex of the RIKEN RI Beam Factory (RIBF) consists of two injectors - heavy ion linac (RILAC and CSM) and K78 MeV AVF cyclotron - and four cyclotrons from the upstream, RRC (K540 MeV), fRC (K570 MeV), IRC (K980 MeV), and SRC (K2600 MeV). In such a multi-stage acceleration system, one of the most important factors for stable operation is to maintain the matching of beam-phases between accelerators. However, drifts of beam-phases have been frequently observed, reasons of which might be the fluctuation of RF-fields, variation of magnetic field, and so on. Hence, it is important to monitor beam-phases constantly, and we have developed a monitoring system using the commercial RF lock-in amplifier model SR844 manufactured by Stanford Research Systems. In addition, the system for monitoring the RF-fields has also been developed to investigate its stability and the correlation with beam-phases. The beam-phases at eleven phase probes installed in the beam transport lines and RF-fields of 25 cavities are monitored in a uranium acceleration. In addition, lock-in amplifiers are also used to obtain good isochronous magnetic fields of three cyclotrons in the RIBF.