Author: Mitsuka, G.
Paper Title Page
MOPLXGD1 The SuperKEKB Has Broken the World Record of the Luminosity 1
 
  • Y. Funakoshi, T. Abe, K. Akai, Y. Arimoto, K. Egawa, S. Enomoto, H. Fukuma, K. Furukawa, N. Iida, H. Ikeda, T. Ishibashi, S.H. Iwabuchi, H. Kaji, T. Kamitani, T. Kawamoto, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, K. Matsuoka, T. Mimashi, G. Mitsuka, F. Miyahara, T. Miyajima, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, K. Nakanishi, H.N. Nakayama, M. Nishiwaki, S. Ogasawara, K. Ohmi, Y. Ohnishi, N. Ohuchi, T. Okada, T. Oki, M.A. Rehman, Y. Seimiya, K. Shibata, Y. Suetsugu, H. Sugimoto, H. Sugimura, M. Tawada, S. Terui, M. Tobiyama, R. Ueki, X. Wang, K. Watanabe, S.I. Yoshimoto, T. Yoshimoto, D. Zhou, X. Zhou, Z.G. Zong
    KEK, Ibaraki, Japan
  • A. Natochii
    University of Hawaii, Honolulu,, USA
  • K. Oide
    CERN, Meyrin, Switzerland
  • R.J. Yang
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
  • K. Yoshihara
    Nagoya University, Nagoya, Aichi, Japan
 
  The SuperKEKB broke the world record of the luminosity in June 2020 in the Phase 3 operation. The luminosity has been increasing since then and the present highest luminosity is 4.65 x 1034 cm-2s-1 with βy* of 1 mm. The increase of the luminosity was brought with an application of crab waist, by increasing beam currents and by other improvements in the specific luminosity. In this paper, we describe what we have achieved and what we are struggling with. Finally, we mention a future plan briefly.  
slides icon Slides MOPLXGD1 [6.235 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPLXGD1  
About • Received ※ 10 June 2022 — Accepted ※ 08 July 2022 — Issue date ※ 10 July 2022  
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MOPOPT031 Renovation of the SR Beam Profile Monitors with Novel Polycrystalline Diamond Mirrors at the SuperKEKB Accelerator 313
 
  • G. Mitsuka, H. Ikeda, T.M. Mitsuhashi
    KEK, Ibaraki, Japan
 
  SR beam profile monitors are fundamental to perform the stable beam operation of SuperKEKB. To suppress thermal deformation of SR extraction mirrors–a long-standing issue in SR monitors–, we developed platinum coated diamond mirrors in 2019. The diamond mirrors are made with optical-quality polycrystal-diamond-substrate with extremely large thermal conductivity, and have a size of 20 mm (W) x 30 mm (H) x 2 mm (D). Surface flatness better than λ/5 was observed in an optical testing with a laser interferometer. The diamond mirrors have been installed in HER and LER in 2020 summer and 2021 summer, respectively. Through irradiation for an year at the beam current greater than 800 mA, no significant deformation of the diamond mirrors has been observed. In this talk, we will discuss the design, construction, and optical testing of the polycrystal diamond mirrors. Also beam measurements performed using an interferometer, a coronagraph, a streak camera, and a fast gate camera will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT031  
About • Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 02 July 2022
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TUOXGD1 Design and Construction of Optical System of the Coronagraph for Beam Halo Observation in the SuperKEKB 769
 
  • G. Mitsuka, H. Ikeda, T.M. Mitsuhashi
    KEK, Ibaraki, Japan
 
  For the observation of beam halo, the coronagraph is designed and constructed in the SuperKEKB. The coronagraph has three stages of optical systems, objective system, re-diffraction system and relay system. Since the SR monitor of SuperKEKB has a long optical path (60 m), we need an objective system with long focal length. The Aperture limit is determined by the diamond mirror which is set in 23.6 m from the source point. Therefore, we must assign this aperture for the entrance pupil of the objective system. For satisfying these conditions, we design a reflective telephoto system based on the Gregorian telescope for the objective system. The focal length is designed to 7028 mm. and front principal point position is designed to the position of diamond mirror. The result of construction, the performance of the objective system has a diffraction limited quality. The re-diffraction system and relay system are also designed based on Kepler type telescope. The result of optical testing using the beam in the HER, we achieved a contrast of 6 order magnitude. Some early result for the observation of beam halo in the HER will also present in this presentation.  
slides icon Slides TUOXGD1 [4.345 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXGD1  
About • Received ※ 09 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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FROXGD3 Injection Beam Measurement Using Synchrotron Radiation Monitor at the SuperKEKB Electron Ring 3121
 
  • H. Ikeda, T.M. Mitsuhashi, G. Mitsuka
    KEK, Ibaraki, Japan
 
  We upgraded the diamond mirror of the SuperKEKB electron ring to extract the good quality synchrotron light in 2020 summer. As a result, the accuracy of profile measurement for each bunch using a gate camera has improved dramatically, and it has become possible to measure the incident beam for each turn. The electron beam was injected with single turn injection mode to measure the properties of the beam and measured turn by turn after injection. In order to convert the measurement results into beam size, convolution by diffraction effect and absolute value calibration using real images were performed. We report the behavior of the injection beam during normal operation of SuperKEKB.  
slides icon Slides FROXGD3 [5.560 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXGD3  
About • Received ※ 09 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 07 July 2022
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