J-PARC Project Newsletter
Special Issue

Japan Proton Accelerator Research Complex under construction
jointly by the High Energy Accelerator Research Organization (KEK) and
the Japan Atomic Energy Agency (JAEA)

Successful beam acceleration up to 30 GeV at the 50-GeV
Synchrotron (MR) of J-PARC

The J-PARC 50-GeV Synchrotron (MR) has successfully accelerated the
proton beams and extracted them to a beam dump.  The first beam
commissioning of the MR started on the 22nd of December, 2008.
Next day, the 23rd of December, at 17:34, the beam was accelerated
to 30 GeV, which is the target energy of the first stage of J-PARC, and
was extracted intentionally to the abort beam dump. The MR is the first
large accelerator in the world designed with an imaginary transition
energy. Preliminary results show that small beam loss occurred in the
first several hundreds of milliseconds, then no significant current drop

was observed until the beam extraction. The acceleration time was 2.5
seconds in this run. Further beam tuning is in progress.
  The next step for the MR is the extraction to the hadron experimental
hall (January 2009) and to the neutrino beam line (April 2009).

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Editorial Board:
Masatoshi ARAI (chair): masatoshi.arai@j-parc.jp
Yujiro IKEDA: ikeda.yujiro@jaea.go.jp
Nobuo OUCHI: ouchi.nobuo@jaea.go.jp
Shinya SAWADA: shinya.sawada@kek.jp
Toshifumi TSUKAMOTO: toshifumi.tsukamoto@kek.jp
English Editor: Dick MISCHKE mischke@triumf.ca
Secretary: Chikako KAIBARA kaibara.chikako@jaea.go.jp
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