Neutron and gamma fields at neutron spallation sources for single-event-effects testing

Monte-Carlo simulations of spallation fields are used to determine neutron and gamma spectra in beams used for single-event-effects testing. Spectra at LANSCE (ICE House) and TSL (ANITA) are calculated using Geant4 with Bertini and binary intranuclear cascade (INC) models. Results with the binary INC model give a good representation of neutron spectra obtained from measurements and independent calculations in each case, and predict gamma dose rates consistent with measured data where these are available. The gamma field in each beam is dominated by a continuum between about 100 keV and about 10 MeV. Integral gamma yields are approximately 0.26 γ p−1 sr−1 and 0.046γ p−1 sr−1 at the ICE House and ANITA, respectively.