• K. Mizushima, T. Furukawa, Y. Iwata, K. Noda, S. Sato, T. Shirai
  NIRS, Chiba-shi
• T. Fujisawa, H. Uchiyama
  AEC, Chiba

A 3D scanning method gated with patient's respiration has been developed for the HIMAC new treatment facility. In the scanning irradiation, the RF-KO slow-extraction method has been used, because of the quick response to beam on/off from the synchrotron. However, a small amount of beam remained just inside the separatrix is extracted just before turning on the transverse RF field, which brings the extra dose. We proposed to apply another transverse RF-frequency component matched with the betatron frequency of the particles in the vicinity of the stopband, in addition to the original transverse RF field for the RF-KO slow-extraction. Using the proposed method, the particles just inside the separatrix, which cause the extra dose, can be selectively extracted during the irradiation; as a result, the extra dose can also be reduced. The validity of this approach has been verified by the simulation and the measurement with the non-distractive 2D beam profile monitor. We will report the result of this approach.

• A. Kiyomichi, T. Adachi, S. Murasugi, R. Muto, H. Nakagawa, J.-I. Odagiri, K. Okamura, H. Sato, Y. Sato, S. Sawada, Y. Shirakabe, H. Someya, K.H. Tanaka, M. Tomizawa, A. Toyoda, E. Yanaoka
  KEK, Ibaraki
• T.I. Ichikawa, K. Mochiki, S. Onuma
  Tokyo City University, Tokyo
• K. Noda
  NIRS, Chiba-shi

J-PARC (Japan Proton Accelerator Research Complex) is a new accelerator facility to produce MW-class high power proton beams at both 3GeV and 50GeV. The Main Ring (MR) of J-PARC can extract beams to the neutrino beam line and the slow extraction beam line for Hadron Experimental Facility. The slow extraction beam is used in various nuclear and particle physics experiments. A flat structure and low ripple noise are required for the spills of the slow extraction. We are developing the spill control system for the slow extraction beam. The spill control system consists of the extraction quadrupole magnets and feedback device. The extraction magnets consist of two kinds of quadrupole magnets, EQ (Extraction Q-magnet) which make flat beam and RQ (Ripple Q-magnet) which reject the high frequent ripple noise. The feedback system, which is using Digital Signal Processor (DSP), makes a ramping pattern for EQ and RQ from spill beam monitor. Here we report the construction status of the extraction magnets and the development of the feedback system.

• K. Noda, T. Furukawa, T. Inaniwa, Y. Iwata, T. Kanai, M. Kanazawa, S. Minohara, K. Mizushima, S. Mori, T.M. Murakami, N. Saotome, S. Sato, T. Shirai, E. Takada, Y. Takei
  NIRS, Chiba-shi
• T. Fujimoto, T. Miyoshi, Y. Sano
  AEC, Chiba

Based on more than ten years of experience of the carbon cancer therapy with HIMAC, we have proposed a new treatment facility for the further development of the therapy with HIMAC. This facility will consist of three treatment rooms: two rooms equipped with horizontal and vertical beam-delivery systems and one room with a rotating gantry. For the beam-delivery system of the new treatment facility, a 3D hybrid raster-scanning method with gated irradiation with patient’s respiration has been proposed. A R&D study has been carried out toward the practical use of the proposed method, although this method was verified by a simulation study. In the R&D study, we have improved the beam control of the size, the position and the time structure for the proposed scanning method with the irradiation gated with patient’s respiration. Further, owing to the intensity upgrade of the synchrotron, we can successfully extend the flattop duration, which can complete one fractional irradiation with one operation period and can increase the treatment efficiency of the gated irradiation. We will report the recent progress on HIMAC for carbon therapy.

• A. Noda, M. Nakao, H. Souda, H. Tongu
  Kyoto ICR, Uji, Kyoto
• M. Grieser
  MPI-K, Heidelberg
• K. Jimbo
  Kyoto IAE, Kyoto
• I.N. Meshkov, A.V. Smirnov
  JINR, Dubna, Moscow Region
• K. Noda, T. Shirai
  NIRS, Chiba-shi
• H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• S. Shibuya
  AEC, Chiba

Funding: The present work was supported by Advanced Compact Accelerator Development program by MEXT of Japanese Government. Support from Global COE, The Next Generation of Physics, is also greatly appreciated.

Creation of 3-dimensional crystalline beam by application of laser-cooling for a Mg ion beam with kinetic energy of 40 keV is a major research subject of the ion storage ring, S-LSR, at ICR, Kyoto University*. Based on the success of longitudinal laser cooling in 2007**, an approach to extend the effect of laser cooling to the transverse degree of freedom has been performed. An indication of heat transfer from the horizontal to longitudinal direction has been obtained by synchro-betatron coupling. By application of bunched beam laser cooling at the operation point around (2.07, 1.10), the momentum spread of the cooled ion beam has been observed to have a peak at a synchrotron tune around 0.07 and simultaneously transverse beam size seems to be reduced in this region. An increase of beam brightness in the horizontal profile has also been observed by measuring spontaneous emission of absorbed laser light. In the present paper, strategy to reach the final 3-dimensional crystalline state by application of 3-dimensional laser cooling by careful adjustment of coupling among 3 degrees of freedom is to be presented based upon the recent experimental results.

*A. Noda, M. Ikegami, T. Shirai, New Journal of Physics, 8, 288-307(2006).
**M. Tanabe et al.,Applied Physics Express 1, 028001-1-028001-3 (2008).

• N. Saotome, T. Furukawa, T. Inaniwa, Y. Iwata, T. Kanai, A. Nagano, K. Noda, S. Sato, T. Shirai, E. Takeshita
  NIRS, Chiba-shi
• T. Kohno
  TIT, Yokohama

The screen monitor system is an important tool for beam diagnostic of the high-energy-beam transport line at the Heavy-Ion Medical Accelerator in Chiba (HIMAC). We have developed a very thin fluorescent film and high speed charge-coupled-device camera. Because the fluorescent film is very thin (ZnS:Ag 2mg/cm³), the beam is measured with semi-non-destructively. Consequently we can use more than two monitors at the same time and multiple locations. Moreover we employ a high-speed three-processer for image processing, the system can be applied for online monitoring and interlock system (100Hz). When the beam profile measured by this system is inevitably changed over the setting tolerance during therapeutic irradiation for the patient, the beam is immediately turned off. The design and measurement result by irradiation test are discussed.