Author: Mihara, S.
Paper Title Page
WEPMP010 8 Gev Slow Extraction Beam Test for Muon to Electron Conversion Search Experiment at J-PARC 2322
 
  • M. Tomizawa, Y. Arakaki, Y. Fukao, Y. Hashimoto, Y. Igarashi, T. Kimura, S. Mihara, M. Moritsu, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, K. Ueno, E. Yanaoka
    KEK, Ibaraki, Japan
  • Y. Fujii
    Monash University, Faculty of Science, Clayton, Victoria, Australia
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  
  A muon to electron conversion search experiment (COMET) planned at J-PARC needs 8 GeV bunched proton beams with a continuous 1 MHz pulse structure. In this experiment, an intensity ratio of the residual to the main pulsed beam, which is expressed as extinction, should be less than the level of 10-10. In RUN78 (Jan. to Feb., 2018), we have succeeded in slow extraction of 8 GeV protons with 7.3×1012 ppp, satisfies the COMET phase-I requirement, and the extinction derived from a timing measurement of secondary particles from the target shows a promising result. A mechanism to explain the measured extinction will be also described in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP010  
About • paper received ※ 01 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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FRXXPLS2 Extinction Measurement of J-PARC MR with 8 GeV Proton Beam for the New Muon-to-Electron Conversion Search Experiment - COMET 4372
 
  • H. Nishiguchi, Y. Fukao, Y. Hashimoto, Y. Igarashi, S. Mihara, M. Moritsu, R. Muto, M. Tomizawa, K. Ueno
    KEK, Tsukuba, Japan
  • Y. Fujii
    Monash University, Faculty of Science, Clayton, Victoria, Australia
  • P. Sarin
    Indian Institute of Technology Bombay, Mumbai, India
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  
  Funding: This work is partially supported by JSPS (Japan Society for the Promotion of Science) : KAKENHI 15K13492 and 16H00876
At J-PARC, extraction tests of a 8GeV pulsed proton beam from Main Ring (MR) have been successfully completed by a team drawn from the Accelerator Laboratory Group and the COherent Muon to Electron Transition (COMET) Experimental Group. The COMET Experiment aims to find new physics beyond the Standard Model by searching for the coherent neutrinoless conversion of a muon to an electron in muonic atoms, so-called mu-e conversion. This requires an extremely clean pulsed beam, and development of this beam plays a key role in the pursuit of the highest level of sensitivity. This successful extraction test is the clearing of a major milestone for the forthcoming experiment. The goal of the extraction tests was to confirm the beam quality under the customized MR operation mode. The J-PARC MR usually accelerates the proton beam (at one bunch per 600ns) up to 30GeV. But in the test, the MR instead accelerates the proton beam (at one bunch per 1.2us) up to 8GeV. The number of protons leaking between proton bunches, so-called EXTINCTION, must be less than one for every 1010 protons in the bunch. Extraction tests in the customized mode were conducted in January and February 2018 and resulted in many successes. In this test, leakage protons between bunches was successfully reduced below the objective of 10−10 of the number of protons in a bunch. This is a great success to guarantee the quality of proton beam required by COMET experiment. In addition, the time development of proton leakage was also precisely studied with several RF settings which enables us to further improve the extinction. In this paper, the result of extinction measurement and future prospect of beam extinction improvement is presented in addition to the detailed description of customized MR operation. 		 
slides icon Slides FRXXPLS2 [13.427 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLS2  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)