• 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.

• B. Parker, M. Anerella, J. Escallier, P. He, A.K. Jain, A. Marone, P. Wanderer, K.-C. Wu
  BNL, Upton, Long Island, New York
• P. Bambade
  LAL, Orsay
• B. Bolzon, A. Jeremie
  IN2P3-LAPP, Annecy-le-Vieux
• P.A. Coe, D. Urner
  OXFORDphysics, Oxford, Oxon
• C. Hauviller, E. Marin, R. Tomás, F. Zimmermann
  CERN, Geneva
• N. Kimura, K. Kubo, T. Kume, S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, T. Tomaru, K. Tsuchiya, J. Urakawa, A. Yamamoto
  KEK, Ibaraki
• A. Seryi, C.M. Spencer, G.R. White
  SLAC, Menlo Park, California

The KEK ATF2 facility, with a well instrumented beam line and Final Focus (FF), is a proving ground for linear collider (LC) technology to demonstrate the extreme beam demagnification and spot stability needed for a LC FF*. ATF2 uses water cooled magnets but the baseline ILC calls for a superconducting FF**. Thus we plan to replace some ATF2 FF magnets with superconducting ones made via direct wind construction as planned for the ILC. With no cryogenic supply at ATF2, we look to cool magnets and current leads with a few cryocoolers. ATF2 FF coil winding is underway at BNL and production warm magnetic measurements indicate good field quality. Having FF magnets with larger aperture and better field quality than present FF might allow reducing the beta function at the FF for study of focusing regimes relevant to CLIC. Our ATF2 magnet cryostat will have laser view ports for cold mass movement measurement and FF support and stabilization requirements under study. We plan to make stability measurements at BNL and KEK to relate ATF2 FF magnet performance to that of a full length ILC R&D prototype at BNL. We want to be able to predict LC FF performance with confidence.

* ATF2 proposal, volumes 1 and 2 at http://lcdev.kek.jp/ILC-AsiaWG/WG4notes/atf2/proposal/index.html
** International Linear Collider Reference Design Report, ILC-REPORT-2007-001, August 2007.