Single Event Upset Phenomena from High Energy Neutrons.

The susceptibility of circumvented and uncircumvented endoatmospheric and exoatmospheric systems to neutron induced SEUSingle Event Upsets was considered in very general terms of nuclear weapon threat and system configuration. For both exiatmospheric and endoatmospheric uncircumvented systems it appears that transient upset effects will be dominated by effects of the prompt ionization pulse. In the worst case neutron-induced SEUs are comparable to the upset levels of the prompt ionization pulse. For current microelectronic components the neutron-induced SEUs do not need to be explicitly considered for uncircumvented systems. The relative susceptibilities should be reviewed with the evolution of microcircuit technology, particularly for possible preferential sensitivity to the localized ionization of a neutron-induced reaction compared to bulk ionization sensitivity. For circumvented systems there is a clearly a potential consideration for exoatmospheric systems and a possible consideration for endoatmospheric systems. Given the threat, microcircuit susceptibility and system performance parameters the calculation of potential concern for a circumvented exoatmospheric system is relatively straightforward. The high atmospheric concern is comparable to the exoatmospheric case. In some cases the relative neutron transport can be slightly enhanced over the prompt gamma pulse transport. The total prompt ionization pulse is also reduced by the increased attenuation of the low energy photons.