• S. Sato, K. Hasegawa, A. Miura, T. Morishita, H. Sako, A. Ueno, H. Yoshikawa
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Z. Igarashi, M. Ikegami
  KEK, Ibaraki
• T. Tomisawa
  JAEA/LINAC, Ibaraki-ken

In the J-PARC LINAC, BPMs with 4 strip lines (up, down, right, left) have been used to monitor the beam position by taking log ratio of signals on the opposite (facing) sides of stirp lines. We are studying possibility to monitor beam phase by measuring phase of summed signal of all four stlip lines. In this paper, status of the study is presented.

• H. Sako, T. Morishita, S. Sato
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• M. Ikegami
  KEK, Ibaraki

Wire Scanner Monitors (WSMs) and Bunch Shape Monitors (BSMs) are going to be installed in the entrance part of ACS (Annular Coupled Structure) section at the energy upgraded J-PARC linac. WSMs are used to measure transverse beam profiles, and BSMs are used to measure longitudinal beam profiles. Both are used to match beams from upstream SDTL (Separated-type Drift Tube Linac) accelerator cavities to ACS. Only a BSM will be installed in the beggining and the best location for the BSM has been chosen through studies of the tuning schemes.

• A. Miura, K. Hasegawa, T. Morishita, H. Sako, H. Yoshikawa
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Z. Igarashi, M. Ikegami
  KEK, Ibaraki
• S. Sato, T. Tomisawa, A. Ueno
  JAEA/LINAC, Ibaraki-ken
• H. Takahashi
  JAEA, Ibaraki-ken

Over hundred beam loss monitors (BLM) in the J-PARC LINAC have been used to measure the beam loss observed during the accelerator operation. Dose rates distributed in LINAC area were compared with beam loss records taken by the BLMs. This paper describes the results of the operational data and their comparisons with the dose rates of LINAC area.

• 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.

• 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.

• 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.