Irradiation Setup Quantifying the Fast and Thermal Neutron and Gamma Shares of a Polyethylene Shielded Americium-Beryllium Neutron Source

The construction of an irradiation workbench for quantitative neutron irradiation at a polyethylene shielded americium-beryllium source is currently in progress. Quantitatively measured and simulated physical quantities like spectral fluence rate, fluence rate, dose rate and ambient dose rate are meant to be catalogued for different distances from the shielding opening and for the individual fast and thermal neutron and photon components of the source radiation field. Only the quantification of the fast neutron field is being presented. Methods include a stilbene detector characterization using a pulse-shape-discrimination-aided Time-of-Flight setup and unfolding pulse-charge spectra via a simple unfolding technique. The determined spectral fluence rates are in good agreement with the performed simulations. Position dependencies are confirmed in the data.