THD —  WGD - Commissioning and Operations   (07-Oct-21   10:00—10:30)
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THDC1 Slow Extraction Operation at J-PARC Main Ring 219
  • M. Tomizawa, Y. Arakaki, T. Kimura, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, Y. Sugiyama, E. Yanaoka, M. Yoshii
    KEK, Ibaraki, Japan
  • K. Noguchi
    Kyushu University, Fukuoka, Japan
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  A high-intensity proton beam accelerated in the J-PARC main ring (MR) is slowly extracted by using the third integer resonance and delivered to the experimental hall. A critical issue in slow extraction (SX) is a beam loss caused during the extraction. A dynamic bump scheme under an achromatic condition provides extremely high extraction efficiency. We have encountered a beam instability in the debunch formation process, which is estimated to be triggered by a longitudinal microstructure of the beam. To suppress this instability, the beam to the MR has been injected into the RF bucket with a phase offset. A newly developed RF manipulation, 2-step voltage debunch, has successfully pushed up the beam power up to 64.6 kW keeping a high extraction efficiency of 99.5%. A drastic beam loss reduction has been demonstrated in the beam test using a diffuser installed upstream of the first electrostatic septum (ESS1). 8 GeV bunched slow extraction tests for the neutrino-less muon to electron conversion search experiment (COMET Phase-I) have been successfully conducted.  
DOI • reference for this paper ※  
About • Received ※ 18 October 2021 — Revised ※ 22 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 03 December 2021
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THDC2 Commissioning of the ESS Front End 225
  • N. Milas, C.S. Derrez, E.M. Donegani, M. Eshraqi, B. Gålander, H. Hassanzadegan, E. Laface, Y. Levinsen, R. Miyamoto, M. Muñoz, E. Nilsson, D.C. Plostinar, A.G. Sosa, R. Tarkeshian, C.A. Thomas
    ESS, Lund, Sweden
  The European Spallation Source, currently under construction in Lund, Sweden, will be the brightest spallation neutron source in the world, when the proton linac driver achieves the design power of 5 MW at 2 GeV beam energy. Such a high power requires production, efficient acceleration, and transport of a high current proton beam with minimal loss. This implies in a challenging design and beam commissioning of this machine. The linac features a long pulse length of 2.86 ms at a relatively low repetition late of 14 Hz. The ESS ion source and low energy beam transport are in-kind contributions from INFN-LNS. Beam commissioning of this section started in September 2018 and continued until early July in 2019. This article presents highlights from a campaign of beam characterizations and optimizations during this beam commissioning stage.  
DOI • reference for this paper ※  
About • Received ※ 17 October 2021 — Revised ※ 20 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 01 December 2021
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