• M. Kanazawa, Y. Iwata
  NIRS, Chiba-shi
• T. Fujimoto
  AEC, Chiba
• K. Watanabe
  Toshiba Medical Systems Corporation, Tochigi

In the routine operation of HIMAC synchrotron, a pulse system of field change with 0.2 Gauss in the monitor dipole magnet (B-clock) is used to generate pattern data in the acceleration system. To eliminate error pulse due to noise in analogue field signal, a clock system locked to a 1.2kHz clock for a power supplies was developed, which can be used to generate pattern data of an acceleration system with maximum frequency of 192kHz. This 1.2kHz clock is synchronized to a power line frequency of 50Hz that will fluctuate about 0.1%, so the clock of 192kHz must also follow this frequency fluctuation. To demonstrate the performance of new clock system, we have tested beam acceleration, and compared with the conventional B-clock system. Acceleration efficiencies were checked with changing these clock rates in the both systems. With these tests, we have found that the relatively low clock rate in the newly developed system is enough to get good acceleration performance. In this paper the clock system, and their beam tests will be presented.

• E. Syresin, D.E. Donets, E.D. Donets, E.E. Donets, V.V. Salnikov, V.B. Shutov
  JINR, Dubna, Moscow Region
• T. Honma, M. Kanazawa, K. Noda
  NIRS, Chiba-shi

The 11C isotopes are produced in the nitrogen gas target irradiated by a proton beam. If the nitrogen target contains 5% of hydrogen, about 5·E12 methane molecules can be produced each 20 minutes. The separated methane is loaded into the ion source. The technique used for formation of radioactive carbon beams was developed and tested in the JINR electron string ion source (ESIS) Krion-2. The measured conversion efficiency of methane molecules to carbon ions is rather high; it corresponds to 17 % for C⁴⁺ ions. The experimentally obtained C⁴⁺ ion intensity in ESIS was about 2·E9 ppp. The new ESIS-5T is under construction in JINR now at project ion intensity of 6·E9 ppp. Accelerated 12C ion beams are effectively used for cancer treatment at HIMAC. The positron emission tomography is the most effective way of tumor diagnostics. The intensive radioactive 11C ion beam could allow both these advantages to be combined. It could be used both for cancer treatment and for on-line PET. Formation of a primary radioactive ion beam at an intensity on the tumor target of 1·E8 pps allows the cancer treatment by the scanning radiation method and on-line dose verification.