Fast Neutron and Gamma induced Radiation Dose Monitoring during Nano-particle Production by Proton beam Irradiation

We report a fast neutron and gamma induced radiation dose and flux monitoring study during the nano-particle production at the proton beam irradiation facility. The monitoring results will be used for understanding of the activation of irradiated samples and the effect to the nano-particle production. A cylindrical shape of BC523A liquid scintillator was used for the fast neutron and gamma monitoring purpose. A neutron tagger module was used for the signal digitization and it has a function of pulse shape discrimination capability by using a charge comparison method. Samples for the nano-particle production were irradiated with 45-MeV proton beam from the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences. The fast neutron detector was located just behind of the sample. Proton beam current from 20 nA to 500 nA was used for the test. The measured neutron and gamma flux, energy spectra, and neutron and gamma induced radiation dose in the liquid scintillator were evaluated and compared with different sample setup. This study showed that the developed detection system is useful for the absorbed dose and flux monitoring of neutron and gamma in the proton beam line.