Validation of calculational determination of 18O(p,n) secondary neutron field

Abstract

Cyclotrons used to produce medical isotopes are relatively widespread. Nowadays, it is popular to place small and compact accelerators directly in hospitals. This approach simplifies handling of the produced radiopharmaceuticals, but it imposes strict radiation safety measures during production. For optimal utilization of isotope production cyclotrons, the exact knowledge of leakage neutron field is essential due to the deep penetration ability of the high energy neutrons and the accompanied secondary radiation production. Our paper presents measurement of the neutron leakage spectra for various angles from an open target assembly at the cyclotron U-120M at NPI of CAS. These spectra are compared with data obtained from a compact medical cyclotron IBA Cyclone 18/9 in UJV Rez and also with activation measurements of reactions with different threshold energies. All data were also compared with calculations made with different Monte Carlo codes using both models and data libraries. The preliminary results show significant disagreement between experiments and theoretical predictions. These findings could have implications not only to the nuclear data community but also to the production accelerators operators at the licensing stage.