Characterization of the Direct and Scattered Neutron Flux Around Cyclotron Target

This study was part of a project that aims to investigate direct and scattered neutron flux, specifically, thermal and epithermal energy ranges around an unshielded PETtrace 880 cyclotron's target in several locations at a medical facility in the western region of Saudi Arabia. Efforts were made to characterize the neutron flux in a diagonal formation using a 3D-printed array within the allowable safe distance from the cyclotron target. The foil activation method was employed to estimate the thermal and epithermal neutron fluxes. The experimental design aimed to irradiate three batches of several sets of gold foils with and without cadmium filters, collect the activated foils and measure the photons emitted from the activated foils using a calibrated Broad Energy Germanium (BEGe) detector. After covering the gold foils with cadmium from two sides (sandwich setup), the mean thermal and epithermal neutron fluxes were found to be in the order of 1.11E + 06 ± 1.10E + 05 neutrons cm−2 s−1 and 7.11E + 05 ± 1.78E + 04 neutrons cm−2 s−1, respectively, at almost all investigated locations. The contribution from the scattered neutrons was found to have an increment in the total flux by 45–86% after applying the sandwich setup. Further experiments will investigate neutrons with higher energies in the fast range to fully characterize the area around the cyclotron's target.