Experimental validation of 23Na( γ, n)22Na cross section.

Photonuclear reactions are gaining importance due to their influence on the shielding and activation of components of widely spread accelerators. Therefore, there is a need for accurate data describing photonuclear reactions. The MT25 microtron operated at NPI was used for validation of cross section in the bremsstrahlung. The gold and copper activation foils with known cross sections were used as flux monitors. The bremsstrahlung spectra was simulated with Geant4 code and the spectral averaged cross section above 10MeV for reaction 23Na(γ, x)22Na was calculated. The experimental result was compared with data from the evaluated data libraries and EXFOR database. It was proved that the facility can be used for validation of cross sections and it was showed that all libraries overestimate the photon cross section on 23Na with the best results with data from JENDL-5 library.

Characterization of the secondary neutron field inside a cyclotron for production of radiopharmaceuticals.

During production of radiopharmaceuticals, the radiation situation in cyclotron pit is an important parameter, which is being monitored to ensure fulfilment of the limits and conditions of safe operation. The neutron flux in the structural components of the accelerator is also an important parameter, because the secondary neutrons are responsible for activation of cyclotron structural components and may even affect structural changes in it. This paper aims to characterize the neutron field in inner positions of medical accelerator IBA 18/9 by activation detectors and by means of scintillation spectrometry. The backward angle measurement was realized also in special liquid water target (H218O) at U120M cyclotron to confirm the data obtained in IBA 18/9 cyclotron.