Author: Matsumura, A.
Paper Title Page
FRC1I3 Devices for High-Efficiency Slow Extraction at J-PARC Main Ring 656
 
  • R. Muto, T. Kimura, S. Murasugi, K. Numai, K. Okamura, Y. Shirakabe, M. Tomizawa, E. Yanaoka
    KEK, Ibaraki, Japan
  • A. Matsumura
    Nihon Advanced Technology Co., Ltd, Ibaraki, Nakagun, Tokaimura, Japan
 
  J-PARC Main Ring (MR) is a syn­chro­tron that ac­cel­er­ates pro­tons up to 30 GeV and sup­plies them to the Neu­trino Ex­per­i­men­tal Fa­cil­ity and the Hadron Ex­per­i­men­tal Fa­cil­ity (HEF). Beam ex­trac­tion from MR to HEF is per­formed by slow ex­trac­tion using third-or­der res­o­nance. In the slow ex­trac­tion a de­vice called an elec­tro­sta­tic sep­tum (ESS) is used to scrape out the beam, and it is im­por­tant to re­duce the beam loss at the sep­tum elec­trode of the ESS in order to sup­ply a high-in­ten­sity beam. So far, we have achieved a slow ex­trac­tion ef­fi­ciency of 99.5% by de­vel­op­ing an ESS with a thin sep­tum elec­trode and tun­ing the bump orbit to re­duce the width of the an­gu­lar dis­tri­b­u­tion of pro­tons at the ESS. In ad­di­tion, a col­li­ma­tor is in­stalled down­stream of the ESS to ab­sorb par­ti­cles scat­tered by the sep­tum elec­trode, thereby re­duc­ing ac­ti­va­tion of the com­po­nents down­stream. In order to achieve fur­ther re­duc­tion of the beam loss, we are cur­rently con­sid­er­ing to in­stall beam dif­fusers and/or bent sil­i­con crys­tals at the up­stream of the ESS. In this talk, we will pre­sent the cur­rent sta­tus of the slow ex­trac­tion de­vices and fu­ture plans to fur­ther im­prove the ex­trac­tion ef­fi­ciency.  
slides icon Slides FRC1I3 [3.167 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-FRC1I3  
About • Received ※ 18 October 2023 — Revised ※ 19 October 2023 — Accepted ※ 23 October 2023 — Issued ※ 01 November 2023
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