Fast-neutron testing at the University of Washington Medical Cyclotron Facility

Because of the cascade of secondary particles, including neutrons, produced in the shielding of large spacecraft, it is important to test the reliability of electronic devices exposed to energetic (fast) neutrons. Additionally, devices located near accelerators, such as those found in cancer therapy clinics, can be exposed to a substantial fluence of neutrons.The energy spectrum of the primary neutron beam has been modeled and benchmarked extensively. To cater to a broader community interested in fast-neutron testing, we have been developing a series of neutron spectra based on scattering the primary neutron beam. A stack of plastic used to scatter the beam, was simulated using MCNP6.2 to analyze the spectra at various locations. We also use MCNP6.2 to investigate the potential of developing a softer neutron spectrum using graphite to reduce the low energy absorption which occurs in the plastic.