• M. Yoshioka, H. Kobayashi, H. Matsumoto
  KEK, Ibaraki

The J-PARC accelerator complex consists of a linear accelerator (330 m long, 181 MeV), a rapid cycling synchrotron (3 GeV RCS, 350 m circumference, 25 Hz) and a slow cycling synchrotron (MR, 30 GeV as a first step energy, 1600 m circumference, typically with 3.5 sec cycle). The RCS provides high intensity proton beam to the materials and life science facility and the MR. The MR has two beam extraction lines. One is a slow extraction system for the hadron physics, and other a fast extraction system for neutrino science. We have to challenge many issues to complete construction of the J-PARC accelerator facility on-schedule in 2008 despite all the hardships, such as the problems included in the original design, technology choices and fabrication procedure of the machine components, and construction of conventional facilities. As a first step of operation, we could commission all accelerator facilities and provide beam to all experimental facilities in 2009 successfully. We will report about analysis of these issues and how to solve them, which is a necessary step to realize the design beam power as a next step, and to challenge the future upgrade beyond the original design.