• N. Carmignani, C. Biscari, M. Serio
  INFN/LNF, Frascati (Roma)
• G. Balbinot, E. Bressi, M. Caldara, M. Pullia
  CNAO Foundation, Milan
• J. Bosser
  CERN, Geneva
• G. Venchi
  University of Pavia, Pavia

The National Centre for Oncological Hadrontherapy (CNAO) is the first Italian centre for the treatment of patients affected by tumours with proton and carbon ions beams. Its status and commissioning results are presented in this conference in several papers. The synchrotron beam extraction is based on the use of a betatron core. The possibility of using the RF-knockout method as alternative system is being investigated, trying to optimise the performances with the already present hardware and minimum upgrades. A multiparticle tracking program has been written to simulate the beam dynamics during the extraction of the synchrotron, and to optimise the parameters of the radio frequency system. Two types of signals have been studied in order to obtain a constant spill with the minimum ripple: a carrier wave with a frequency and amplitude modulation, and a noise at a given range of frequencies modulated in amplitude. The results of the optimisation and the parameters of the proposed system are presented.