Source term and activation analysis for the new cyclotron for medical applications at HZDR with MCNP6 and FLUKA

A new cyclotron is currently being commissioned at the Center of Radiopharmaceutical Cancer Research of the HZDR. The energy range of up to 28 MeV protons for the 18O(p,n)18F reaction required a recalculation of the neutron source terms needed in the shielding calculations, since the manufacturer supplied data was based on a 24 MeV proton beam. The radiation transport programs MCNP6 and FLUKA were used to calculate the neutron fluence emerging from the 18O-enriched water target during operation. Both Monte Carlo programs agree within 20 % on the neutron yield per incident proton for 24 and 28 MeV proton beams, while at 24 MeV, the manufacturer supplied data is considerably lower than the simulation results. To validate the radiation fields obtained in the simulations, an experimental program has been started using activation samples which are placed close to the water target of the cyclotron which is currently used to produce 18F. After irradiation, the samples are analyzed, and the resulting activation is compared to Monte Carlo calculations of the expected sample activation.