The methodology of characterization of neutron leakage field from PET production cyclotron for experimental purposes

During the production of 18F isotope for radiopharmaceuticals in 18O(p,n)18F reactions, the leakage neutrons are mostly considered as a waste product. The utilization of a cyclotron based neutron source might be an interesting application because its average energy is relatively high and emissivity is quite strong. Thus its use might be useful in many fields of neutron based research. This paper aims to define the methodology and its following use for the characterization of the secondary neutron field leaking from 18O enriched H2O target in IBA Cyclone 18/9. Experimental characterization is based on the employment of independent methods, namely the proton recoil method using a stilbene scintillation detector and neutron activation analysis with selected IRDFF materials. Neutron field characteristics were also tested by calculation in the standard MCNP6 code model and using FENDL-3, TENDL-2017 nuclear data libraries for (p,n) reactions. The calculation models have been found as discrepant in some quantities more or less, thus it is recommended to use experimental characterization as a sole method.