Keyword: MMI
Paper Title Other Keywords Page
MOXAA02 Highlights from SuperKEKB Commissioning luminosity, optics, coupling, detector 1
 
  • Y. Ohnishi
    KEK, Ibaraki, Japan
  
  SuperKEKB is an electron-positron double-ring asymmetric-energy collider to search new physics phenomena appeared in B-boson decays. In order to accomplish this purpose, the huge statics, it is necessary for 40 times the luminosity as high as the predecessor KEKB collider. The strategy is that the vertical beta function at the IP is squeezed down to 1/20 and the beam currents doubles those of KEKB while keeping the same beam-beam parameter. The vertical beta function at the IP will be much smaller than the bunch length, however, the hourglass effect which degrades the luminosity will be reduced by adopting a novel ‘‘nano-beam’ scheme. First of all, the Phase 2 commissioning was focused on the verification of nano-beam scheme. Secondary, beam related background at the Belle II detector was also studied for the preparation of the pixel vertex detector installed before the Phase 3 operation. The preliminary results and accomplishments of the commissioning in Phase 2 will be reported in this article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-MOXAA02  
About • paper received ※ 12 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUOAB04 Optics Corrections including IP Local Coupling at SuperKEKB coupling, luminosity, optics, operation 63
 
  • A. Morita, H. Koiso, K. Ohmi, Y. Ohnishi, H. Sugimoto, D. Zhou
    KEK, Ibaraki, Japan
  
  The phase-2 commissioning of the SuperKEKB accelerator with the interaction point(IP) has been performed from March 19 to July 17. In the collision operation during this commissioning, the vertical beta function at the IP was squeezed down to 3mm. In order to achieve such low beta collision operation, many optics corrections were performed. We present the result of those optics measurement and correction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB04  
About • paper received ※ 12 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUOBB01 Optics Aberration at IP and Beam-beam Effects luminosity, coupling, emittance, optics 66
 
  • K. Ohmi, Y. Funakoshi, H. Koiso, A. Morita, Y. Ohnishi, D. Zhou
    KEK, Ibaraki, Japan
  • K. Hirosawa
    Sokendai, Ibaraki, Japan
  
  Collision in SuperKEKB phase II commissioning has started in April 2018. Luminosity was lower than the geomterical value even in very low bunch current. Linear x-y coupling at IP caused by skew of QCS was conjectured as error source. x-y coupling correction using skew corrector of QCS resulted in luminosity recover of 2 times. After the QCS skew correction, luminosity is still limited at relatively low bunch current. Nonlinear x-y coupling at IP is conjectured as a source of the luminosity limitation. We discuss effects of linear and nonlinear x-y coupling at IP on the beam-beam performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB01  
About • paper received ※ 25 September 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUYAA04 Study to Mitigate Electron Cloud Effect in SuperKEKB electron, photon, simulation, solenoid 95
 
  • Y. Suetsugu, H. Fukuma, K. Ohmi, K. Shibata, M. Tobiyama
    KEK, Ibaraki, Japan
  
  During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04  
About • paper received ※ 27 September 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUYBA01 Benchmarking of Simulations of Coherent Beam-beam Instability simulation, experiment, luminosity, synchrotron 103
 
  • K. Ohmi, H. Koiso, Y. Ohnishi
    KEK, Ibaraki, Japan
  • D. El Khechen
    CERN, Geneva, Switzerland
  • K. Hirosawa
    Sokendai, Ibaraki, Japan
  
  Coherent beam-beam nstability in head-tail mode has been predicted in collision with a large crossing angle. The instability is serious for design of future e+e− colliders based on the large crossing angle collision. It is possible to observe the instability in SuperKEKB commissioning. Horizontal beam size blow-up of both beams has been seen depending on the tune operating point. We report the measurement results of the instability in SuperKEKB phaseII commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYBA01  
About • paper received ※ 25 September 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPAB07 Commissioning of Positron Damping Ring and the Beam Transport for SuperKEKB emittance, linac, positron, operation 152
 
  • N. Iida, Y. Funakoshi, H. Ikeda, T. Ishibashi, H. Kaji, T. Kamitani, M. Kikuchi, T. Kobayashi, H. Koiso, F. Miyahara, T. Mori, Y. Ohnishi, Y. Seimiya, H. Sugimoto, H. Sugimura, R. Ueki, Y. Yano, D. Zhou
    KEK, Ibaraki, Japan
  
  The Positron Damping Ring (DR) for SuperKEKB successfully started its operation in February 2018, and the commissioning was continued until the end of SuperKEKB Phase 2 in July without serious troubles. This paper describes achievements of the beam commissioning of injection and extraction lines (LTR and RTL) between the LINAC and DR. In the LTR commissioning, the positron beam with high emittance, wide energy spread, and high charge were transported and injected into the DR. In the RTL commissioning, special cares were necessary to preserve the low emittance. The observed emittance growth in the RTL was not a problem for Phase 2, but it should be resolved in the coming Phase 3. In this paper, brief results of the commissioning of the DR is also reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPAB07  
About • paper received ※ 20 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPBB05 Beam Instrumentation at SuperKEKB timing, injection, feedback, detector 169
 
  • G.M. Mitsuka, M. Arinaga, J.W. Flanagan, H. Fukuma, H. Ikeda, H. Ishii, S.H. Iwabuchi, K. Mori, E. Mulyani, M. Tejima, M. Tobiyama
    KEK, Ibaraki, Japan
  • G. Bonvicini
    Wayne State University, Detroit, Michigan, USA
  • E. Mulyani
    Sokendai, Ibaraki, Japan
  • G.S. Varner
    University of Hawaii, Honolulu,, USA
  
  Phase 2 commissioning of the SuperKEKB electron-positron collider has been performed with final focus optics from February 8 to July 17, 2018. The main aims of Phase 2 commissioning were to verify the novel nano-beam collision scheme and achieve the machine luminosity O(1034 cm-2s-1). The beam instruments including the bunch-by-bunch feedback and orbit feedback systems, which are central to the beam diagnostics at SuperKEKB, were successfully operated throughout Phase 2. In this talk, we will present the commissioning results focusing on beam diagnostics and show prospects for the final phase of commissioning from next spring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPBB05  
About • paper received ※ 26 September 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPBB06 Fast Luminosity Monitoring for the SuperKEKB Collider (LumiBelle2 Project) luminosity, detector, feedback, monitoring 173
 
  • P. Bambade, S. Di Carlo, D. Jehanno, V. Kubytskyi, C.G. Pang, Y. Peinaud
    LAL, Orsay, France
  • Y. Funakoshi, S. Uehara
    KEK, Ibaraki, Japan
  
  Funding: - MSCA RISE E-JADE project, funded by European Commission grant number 645479 - Toshiko Yuasa France-Japan Particle Physics Laboratory (project A-RD-08)
LumiBelle2 is a fast luminosity monitoring system prepared for SuperKEKB*. It uses sCVD diamond detectors placed in both the electron and positron rings to measure the Bhabha scattering process at vanishing scattering angle. Two types of online luminosity signals are provided, a Train-Integrated-Luminosity at 1 kHz as input to the dithering feedback system used to maintain optimum overlap between the colliding beams in horizontal plane, and Bunch-Integrated-Luminosities at about 1 Hz to check for variations along the bunch trains. Individual beam sizes and offsets can also be determined from collision scanning. The design of LumiBelle2 will be described and its performance during the Phase-2 commissioning of SuperKEKB will be reported.
*First Tests of SuperKEKB Fast Luminosity Monitors During 2018 Phase-2 Commissioning" (WEPAL038) and "Early Phase 2 Results of LumiBelle2 for the SuperKEKB Electron Ring"(THYGBE4) presented at IPAC18 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPBB06  
About • paper received ※ 24 September 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEXBA04 Early Commissioning of the Luminosity Dither System for SuperKEKB luminosity, feedback, controls, electron 212
 
  • Y. Funakoshi, T. Kawamoto, M. Masuzawa, S. Nakamura, T. Oki, M. Tobiyama, S. Uehara, R. Ueki
    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 double ring collider at KEK which aims at a peak luminosity of 8 x 1035 cm-2s-1 by using what is known as the ’nano-beam’ scheme. A luminosity dither system is employed for collision orbit feedback in the horizontal plane. This paper reports a system layout of the dither system and algorithm tests during the SuperKEKB Phase 2 commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEXBA04  
About • paper received ※ 15 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEOAB01 Commissioning Status of SuperKEKB Vacuum System vacuum, photon, wiggler, 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  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPBB01 Operation of SuperKEKB in Phase 2 injection, operation, vacuum, quadrupole 286
 
  • Y. Funakoshi, Y. Arimoto, H. Ikeda, T. Ishibashi, N. Ohuchi, S. Terui, X. Wang
    KEK, Ibaraki, Japan
  
  The Phase 2 commissioning of SuperKEKB was performed from March to July 2018. In this report, the operation statistics and the QCS quench issue which we encountered during Phase 2 are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEPBB01  
About • paper received ※ 20 October 2018       paper accepted ※ 19 February 2019       issue date ※ 21 April 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)