Commissioning of Japan Proton Accelerator Research Complex (J-PARC) main ring (MR) was started on May 2008. Very large magnetic fieldripples of the order of 10^－2 were foundin the dipole, the quadrupole andthe sextupole magnets in the MR. In order to reduce the ripples, we modified the magnet-power supplies, which includes removal of the 600 Hz trap filter, addition of another DCCT to subtract the common mode signal and symmetrization of the cabling to all the magnets. The modification achieved the magnetic field ripples of the order of 10^－3 during the injection and 10^－4 during the extraction. We have succeeded in accelerating of the protons up to 30 GeV, which were extracted to the hadron experimental hall and the neutrino beam line.

Usually an electric circuit is placed in the circumstance, and the electric circuit always emits electromagnetic noise to the circumstance and receives noise from the circumstance. Previously, we did not understand how the electromagnetic noise is generated in the circuit. This is related with the fact that the existing multiconductor transmission-line theory is not arranged to treat the electromagnetic noise, and we cannot calculate the coupling of the transmission lines with the circumstance. We have constructed a new multiconductor transmission-line theory and understood the noise problem in terms of the theory. We show that usual electric circuits always emit and absorb noise. To cure this problem, we should introduce one more line (third line) to the electric circuit and use this line as the central line for symmetric arrangement of the power supplies and electric loads to minimize the noise. We can then construct an electric circuit, which is free from noise.

My wandering about accelerator extended more actively to challenge new fields of physics with use of the high-energy heavy-ion beams. With people in the Japanese nuclear-physics community, we proposed to build a new high-energy heavy-ion synchrotron, named NUMATRON, which accelerates nuclear beam up to a few GeV per nucleon. Since it was brand-new field of nuclear physics, when proposed, we started to join a program at the LBL Bevatron/ BEVALAC to learn and to get experience in the new field. Although the NUMATRON proposal was not realized while the competing TRISTAN proposal was accepted, the experience and the effort for NUMATRON opened the new horizon of nuclear science in various directions.

A new type of front-end controller was developed for accelerator control systems based on the Experimental Physics and Industrial Control System (EPICS). The controller comprises a new type of CPU, the F3RP61, running Linux and existing I/O modules for the FA-M3 Programmable Logic Controller (PLC). By running the EPICS core program on the CPU, it turns into an EPICS Input/Output controller (IOC) to replace the existing front-end control system, which is composed of a VME/VxWorks-based IOC and ordinary PLCs. The consolidation of the front-end control significantly reduces the workload for developing and maintaining the application programs as well as the relevant EPICS driver programs. Tens of F3RP61-based IOCs have been operating well for more than a year in the control systems of accelerators in operation, such as KEKB and J-PARC, demonstrating the stability of EPICS on the F3RP61.

A superconducting magnet system for the J-PARC neutrino beam line had been under construction since 2004. 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. The SCFMs had been developed by 2004, mass-produced since 2005, and completed by summer 2008. The system has been installed since Feb. 2008 till the end of 2008. The commissioning of the system has been carried out in Jan. to Mar. 2009. The paper summarizes the magnet development and system overview including cryogenics. The paper also reports the production, installation and commissioning status.

The RIKEN radio isotope (RI) beam factory requires an intense beam (more than 1 pµA on target) of high charged heavy ions to produce intense RI beam using projectile like fragmentation. In the last decade, the effects of the key parameters (magnetic field configuration, gas pressure etc) on the ECR plasma have been revealed and the performance has been dramatically improved. Such basic studies give us how to optimize the ion source structure. Based on these studies and the modern superconducting technology, we successfully constructed the new superconducting electron cyclotron resonance ion source (SC-ECRIS) which has a flexible magnetic field configuration to enlarge the ECR zone and to optimize the field gradient at ECR point. It has an optimum field strength for the operation of 28 GHz microwave. In the first test experiment, we investigated the effect of ECR zone size, magnetic field configuration, and microwave power on the beam intensity of the highly charged heavy ions with 18 GHz microwaves. In this article, we present the structure of the ion source and these experimental results with 18 GHz microwave in detail.

21st International Conference on Magnet Technology was held it Heifei in China from October 19th to 23rd in 2009. The overview of the conference is reported.

The 12th International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS2009) was held at Kobe, Japan in Oct. 12–16, 2009. The summary of the conference will be reported in this paper.