Keyword: wiggler
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TUPAB03 Overall Injection Strategy for FCC-ee emittance, linac, booster, collider 131
 
  • S. Ogur, F. Antoniou, T.K. Charles, B. Härer, B.J. Holzer, Y. Papaphilippou, L. Rinolfi, T. Tydecks, F. Zimmermann
    CERN, Geneva, Switzerland
  • M. Aiba
    PSI, Villigen PSI, Switzerland
  • A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • I. Chaikovska, R. Chehab
    LAL, Orsay, France
  • O. Etisken
    Ankara University, Faculty of Sciences, Ankara, Turkey
  • K. Furukawa, N. Iida, T. Kamitani, F. Miyahara
    KEK, Ibaraki, Japan
  • E.V. Ozcan
    Bogazici University, Bebek / Istanbul, Turkey
  • S.M. Polozov
    MEPhI, Moscow, Russia
 
  The Future Circular electron-positron Collider (FCC-ee) requires fast cycling injectors with very low extraction emittances to provide and maintain extreme luminosities at center of mass energy varying between 91.2-385 GeV in the collider. For this reason, the whole injector complex table is prepared by putting into consideration the minimum fill time from scratch, bootstrapping, transmission efficiency as well as store time of the beams in synchrotrons to approach equilibrium emittances. The current injector baseline contains 6 GeV S-band linac, a damping ring at 1.54 GeV, a prebooster to accelerate from 6 to 20 GeV, which is followed by 98-km top up booster accelerating up to final collision energies. Acceleration from 6 GeV to 20 GeV can be provided either by Super Proton Synchrotron (SPS) of CERN or a new synchrotron or C-Band linac, distinctively, which all options are retained. In this paper, the current status of the whole FCC-ee injector complex and injection strategies are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPAB03  
About • paper received ※ 20 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
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WEXAA02 Polarization Issues at CEPC polarization, resonance, booster, electron 182
 
  • S.A. Nikitin
    BINP SB RAS, Novosibirsk, Russia
 
  We study a possibility of obtaining transversely polarized electron-positron beams at the CEPC collider. At the beam energy of 45 GeV, this requires the use of the special wigglers to speed up the radiative self-polarization process. A numerical estimation of the depolarizing effect of the collider field errors is made, taking into account the modulation of the spin precession frequency by synchrotron oscillations. In addition, we consider an alternative possibility of obtaining polarization by accelerating the polarized particles in the booster and then injecting them into the main ring. This option saves time spent on the polarization process, and is also crucial for obtaining longitudinal polarization.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEXAA02  
About • paper received ※ 19 September 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
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WEOAB01 Commissioning Status of SuperKEKB Vacuum System vacuum, MMI, photon, detector 226
 
  • K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui
    KEK, Ibaraki, Japan
 
  In the upgrade from the KEKB to the SuperKEKB, approximately 93% and 20% of the beam pipes and vacuum components of the positron ring and the electron ring were replaced with new ones. In the Phase-1 commissioning in 2016, vacuum scrubbing and confirmation of the stabilities of new vacuum components at approximately 1 A were carried out. Though some problems such as pressure bursts accompanying beam losses were revealed, no serious problem was found in the vacuum system. During the subsequent shutdown, the countermeasures against the problems were taken, and new beam pipes and components such as beam collimators were installed. The Phase-2 commissioning, where beam collision tuning was mainly performed, was carried out from March to July 2018. The collimators worked very well to suppress the background noise of the Belle-II detector, though some of them were damaged by the beam. The frequency of the pressure burst drastically decreased though the typical beam currents were lower than those of the Phase-1. The vacuum system of the SuperKEKB has been working generally well so far. The total beam doses of the SuperKEKB exceeded 1000 Ah, and the pressures decreased as expected.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEOAB01  
About • paper received ※ 02 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
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