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

The beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) MR (Main Ring) was started from May 2008 and is in progress. As usual, injection tuning is in the first stage and strongly related to other tuning items. Starting with design schemes, making adjustment due to leakage field influence from injection septum, doing envelope matching considering dilution of beam profile in Main Ring are reported in this paper. The 'Without bump' scheme was got on June 15th 2008, while 'With bump' scheme on February 15th 2009. Beam orbit betatron oscillation to the MR close orbit which cause by injection error is less than 1 mm both in horizontal and vertical direction. Meanwhile, Beam Optics matching for 3 GeV beam from 350BT to MR has been well done too, which is also very important.

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

• H. Fujimori, Z. Igarashi, Y. Irie, Y. Sato, M.J. Shirakata, I. Sugai, A. Takagi, Y. Takeda
  KEK, Ibaraki

The carbon stripping foil is the key element for the high-intensity proton accelerator. At KEK, the foil test system using the 650keV H^- Cockcroft-Walton accelerator is in operation, which can simulate the energy depositions to the foil with the same amount in the J-PARC. In order to quantatively observe the foil degradations (such as foil thinning, pin-hole production) during irradiation, online energy and particle analyzing system is under construction. This report outlines the design detail of the analyzing system including the detectors.

• A.Y. Molodozhentsev, T. Koseki, M.J. Shirakata, M. Tomizawa
  KEK, Ibaraki
• A. Ando, J. Takano
  J-PARC, KEK & JAEA, Ibaraki-ken

During the early J-PARC Main Ring commissioning and the machine operation with the moderate beam power the 'fast extraction' bare working point has been chosen to provide the machine operation in the safe regime. We discuss main experimental results obtained so far and compare with the results of the computational model of the machine, including the first experimental approach to minimize the effect of the 'sum' linear coupling resonance. The strategy to increase the beam power without changing the operational working point is presented by keeping the moderate space-charge detuning. The advantage of the second harmonic MR RF cavity, including the estimation of the beam losses during the injection and acceleration processes, is discussed.

• M.J. Shirakata, T. Oogoe
  KEK, Ibaraki

The beam transport line between 3 GeV Rapid Cycling Synchrotron and Main Ring has a beam collimator system in order to improve the quality of injected beam in the main ring. The beam power deposited into the collimators is required to be increased for high intensity beam operation. The tolerance of existing radiation shield becomes insufficient, even though there is no heat problem. The gate-type shield system has been preparing in order to satisfy both the radiation shielding and feasibility of maintenance. The development of movable gate-type shield system is reported here, which fully covers more than 20 meters long collimator section.