Author: Tobiyama, M.
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MOOB01 Beam Commissioning of SuperKEKB Rings at Phase-2 6
  • M. Tobiyama, M. Arinaga, J.W. Flanagan, H. Fukuma, H. Ikeda, H. Ishii, S.H. Iwabuchi, G.M. Mitsuka, K. Mori, M. Tejima
    KEK, Ibaraki, Japan
  • G. Bonvicini
    Wayne State University, Detroit, Michigan, USA
  • E. Mulyani
    Sokendai, Ibaraki, Japan
  • G.S. Varner
    University of Hawaii, Honolulu,, USA
  The Phase 2 commissioning of SuperKEKB rings with Belle II detector began in Feb. 2018. Staring the commissioning of positron damping ring (DR), the injection and storage of the main rings (HER and LER) smoothly continued in Apr., 2018. The first collision has been achieved on 26th Apr. with the detuned optics (200 mm x 8 mm). Performance of beam instrumentation systems and the difficulties encountered during commissioning time will be shown.  
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MOPA02 Beam Diagnostics for SuperKEKB Damping Ring in Phase-II Operation 29
  • H. Ikeda, M. Arinaga, J.W. Flanagan, H. Fukuma, H. Ishii, S.H. Iwabuchi, G.M. Mitsuka, K. Mori, M. Tejima, M. Tobiyama
    KEK, Ibaraki, Japan
  The SuperKEKB damping ring (DR) commissioning started in February 2018, before main ring (MR) Phase-II operation. We constructed the DR in order to deliver a low-emittance positron beam. The design luminosity of SuperKEKB is 40 times that of KEKB with high current and low emittance. A turn-by- turn beam position monitor (BPM), transverse feedback system, synchrotron radiation monitor (SRM), DCCT, loss monitor using ion chambers, bunch current monitor and tune meter were installed for beam diagnostics at the DR. An overview of the instrumentation and status will be presented.  
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TUPC13 Early Commissioning of the Luminosity Dither Feedback for SuperKEKB 328
  • M. Masuzawa, Y. Funakoshi, T. Kawamoto, S. Nakamura, T. Oki, M. Tobiyama, S. Uehara
    KEK, Ibaraki, Japan
  • P. Bambade, S. Di Carlo, D. Jehanno, C.G. Pang
    LAL, Orsay, France
  • D.G. Brown, A.S. Fisher, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • D. El Khechen
    CERN, Geneva, Switzerland
  • U. Wienands
    ANL, Argonne, Illinois, USA
  SuperKEKB is an electron-positron collider, which aims to achieve a peak luminosity of 8×1035 cm-2 s−1 using what is known as the "nano-beam" scheme. This paper reports on the commissioning and performance of a luminosity dither feedback. The system, based on one previously used at SLAC for PEP-II, is employed for collision orbit feedback in the horizontal plane. Twelve air-core Helmholtz coils drive the positron beam sinusoidally at a frequency near 80 Hz, forming a closed bump at the interaction point. A lock-in amplifier detects the amplitude and phase of the corresponding frequency component of the luminosity signal. When the beams are aligned for peak luminosity, the magnitude of the luminosity component at the dithering frequency becomes zero. The magnitude grows as the beams are offset, and the phase shifts by 180 degrees when the direction of the necessary correction reverses. The hardware and algorithm were tested during SuperKEKB Phase II run. The electron beam orbit was successfully adjusted to minimize the amplitude of the dither frequency component of the luminosity signal, and the optimal condition was maintained by continuously adjusting the electron beam orbit.  
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