Author: Tobiyama, M.
Paper Title Page
TUPAB009 SuperKEKB Optics Measurements Using Turn-by-Turn Beam Position Data 1352
 
  • J. Keintzel, R. Tomás García
    CERN, Geneva, Switzerland
  • H. Koiso, G. Mitsuka, A. Morita, K. Ohmi, Y. Ohnishi, H. Sugimoto, M. Tobiyama, R.J. Yang
    KEK, Ibaraki, Japan
 
  SuperKEKB, an asymmetric electron-positron collider, has recently achieved the world record instantaneous luminosity of 2.8 × 1034 \si{cm-2s-1} using crab-waist collision scheme. In order to reach the design value of 6×1035 \si{cm-2s-1} a vertical beta function at the interaction point of §I{0.3}{mm} is required, demanding unprecedented optics control. Turn-by-turn beam position data could enable fast optics measurements for rapid identification of unexpected error sources. Experiments exploring various data acquisition techniques at different squeezing steps during commissioning are presented and compared to results obtained from closed orbit distortion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB009  
About • paper received ※ 18 May 2021       paper accepted ※ 10 June 2021       issue date ※ 24 August 2021  
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TUPAB010 Impact of Bunch Current on Optics Measurements in SuperKEKB 1356
 
  • J. Keintzel, R. Tomás García, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Ishibashi, H. Koiso, G. Mitsuka, A. Morita, K. Ohmi, Y. Ohnishi, H. Sugimoto, S. Terui, M. Tobiyama, R.J. Yang, D. Zhou
    KEK, Ibaraki, Japan
 
  SuperKEKB has recently achieved the world record instantaneous luminosity of 2.8 × 1034 \si{cm-2s-1} and aims at reaching a target luminosity of about 6 × 1035 \si{cm-2s-1}. To accomplish this goal it is planned to increase beam currents up to §I{3.6}{A} and §I{2.6}{A} for the positron and the electron ring, respectively. Increasing the beam currents and, in particular, the number of leptons per bunch, can impact the optics parameters obtained by turn-by-turn measurements, such as the betatron tune or phase advance. Optics measurements performed at various bunch currents can give first indications of possible intensity dependent effects. In this paper, the effect of varying bunch current on optics measurements at SuperKEKB is explored.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB010  
About • paper received ※ 18 May 2021       paper accepted ※ 10 June 2021       issue date ※ 30 August 2021  
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WEPAB359 Report on Collimator Damaged Event in SuperKEKB 3541
 
  • S. Terui, Y. Funakoshi, H. Hisamatsu, T. Ishibashi, K. Kanazawa, Y. Ohnishi, K. Shibata, M. Shirai, Y. Suetsugu, M. Tobiyama
    KEK, Ibaraki, Japan
 
  Collimator jaws for SuperKEKB main ring, which is an electron-positron collider, installed to suppress background noise in a particle detector complex named Belle II. In high current operations with 500 mA or more, jaws were occasionally damaged by hitting abnormal beams. This trouble is a low-frequency, which is once-a-commissioning period currently, but high-consequence one because we are not able to apply high voltage on detectors in Belle II by high backgrounds. At this moment this jaw damage event occurs, we observed pressure burst near the collimator with the beam abort, there was no sign of beam oscillation indicating instability, and the beam intensity suddenly decreased a few turns before the abort. I predict that the cause of this jaw damage was that a sudden change of the beam energy by the collision with dust. In this paper, the explanation of the observation result of this events and tracking simulation of beam colliding with dust are reported.  
poster icon Poster WEPAB359 [3.869 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB359  
About • paper received ※ 17 May 2021       paper accepted ※ 22 July 2021       issue date ※ 20 August 2021  
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