• T. Ogitsu, Y. Ajima, O. Araoka, Y. Fujii, N. Hastings, N. Higashi, M. IIda, N. Kimura, T. Kobayashi, Y. Makida, T. Nakadaira, T. Nakamoto, H. Ohhata, T. Okamura, K. Sakashita, K. Sasaki, M. Shibata, S. Suzuki, K. Tanaka, A. Terashima, T. Tomaru, A. Yamamoto
  KEK, Ibaraki
• A. Ichikawa
  Kyoto University, Kyoto
• H. Kakuno
  University of Tokyo, Tokyo

A superconducting magnet system for the J-PARC neutrino beam line was completed at the end of 2008. The system consists of 14 doublet cryostats; each contains 2 combined function magnets (SCFM). The SCFM uses two single layer left/right asymmetric coils that produce a dipole field of 2.6 T and quadrupole of 19 T/m. By 2008, the world first SCFM had been developed and tested successfully at KEK. The mass-production was started in 2005, and completed by summer 2008. The system installation and commissioning took place from Feb. 2008 to Mar. 2009. The beam operation was started in April 2009 and the first neutrino beam was generated on April 23rd. Since then beam operation and commissioning to increase beam intensity has been performed to achieve the near term milestone of 100 kW beam operation. The paper briefly summarizes the history of SCFM development and the system construction as an introduction to a discussion on beam operation experience of the SCFM system.

• G.H. Wei
  KEK/JAEA, Ibaraki-Ken
• A. Ando, T. Koseki, J. Takano
  J-PARC, KEK & JAEA, Ibaraki-ken
• K. Fan, S. Igarashi, K. Ishii, T. Nakadaira, M. Tomizawa, M. Uota
  KEK, Ibaraki
• H. Harada, P.K. Saha
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

The beam commissioning of J-PARC/MR has been started from May 2008 and is in progress*. One key purpose of MR commissioning is the 30 GeV beam fast extraction to Neutrino beam line, which reflect the overall commissioning result. In the MR, the third straight section is assigned for the fast extraction. 5 kickers and 8 septa were installed there, which can give beam a bipolar kick to inside or outside of MR. Inside kick means beam to Neutrino Oscillation Experiment, while outside kick means beam dumped to abort line. However before commissioning, the measured magnetic field distribution of each septa shows non-linear profile along the horizontal direction. In order to find the influence, a simulation with these measured field has been performed. Depends on this study and some OPI (Operation Interface) made by code SAD for orbit modification online, fast extraction of 30 GeV beam to Neutrino line has been achieved on April 23rd 2009. Beam orbit have been tuned to less than 0.5 mm and 0.1 mrad in both horizontal and vertical at the beginning of Neutrino line, which is also the end of MR fast extraction. And so far, 100 kW continual operation to neutrino line have been achieved, too.

* T. Koseki, "Challenges and Solutions for J-PARC Commissioning and Early Operation", in these proceedings