Approach for Realization of High Intensity Cyclotron Beam

Demands of radionuclide for medical use are expected to increase rapidly from now on. Radionuclides will be used for nuclear medicine not only for diagnostic purposes such as positron emission tomography (PET) and Single-photon emission computed tomography (SPECT), but also for targeted radionuclide therapy (TRT). It would also be applied to a cancer treatment with the use of radioactive $^{11}$C beam irradiation, which enables simultaneous imaging of irradiated field of the patient by the use of Open-PET during treatment. High intensity beam is inevitable for radionuclide production to realize such applications.At NIRS of QST (National Institutes for Quantum and Radiological Science and Technology), there exist a cyclotron NIRS-930 [1] (Thomson-CSF, Kb=110 MeV, Kf=90 MeV) and two small cyclotrons used exclusively for short-lived radionuclide production. We are aiming to improve intensity of NIRS-930.For the purpose of increasing the beam intensity, it is important to understand the beam behavior and the cause of beam loss. As we can measure beam loss at the limited points where the prove electrodes exist, we need a simulation of beam in the cyclotron using computers in order to get more precise information related to beam losses. There exist some simulation codes for ion beam in cyclotron considering space charge effects. We utilized SNOP code [2], which was developed at JINR, because it is superior in simulating the beam of whole cyclotron from injection to extraction. The electric or magnetic fields of each element were calculated with TOSCA [3]. Simulation study at NIRS-930 using SNOP code reproduced the beam parameters in case of harmonic 1 [4]. Then we performed the simulation of 18 MeV protons with harmonic 2, which is one of the most commonly used beams for radionuclide production now.In the present paper, simulation studies for finding better operating parameters and upgrading scheme will be presented.\n[1] S. Hojo et al., Proc. of HIAT2015 MOPA07 (2015)[2] V. L. Smirnov, Physics of Particles and Nuclei 46 pp. 940-955 (2015)[3] OPERA-3D, Cobham plc http://www.cobham.com/[4] V.L. Smirnov et al., Proc. of IPAC2012 292 (2012)12th European Conference on Accelerators in Applied Researc