Neutron Generated Single-Event Upsets in the Atmosphere

Heavy cosmic ray nuclei are mostly attenuated with a shielding of 50 g/cm2 atmospheric gas. However, the shielding acts as a generator of neutrons, evaporated or knocked out of nuclei. These neutrons generate highly ionizing nuclear recoils that produce single-event upsets in microelectronic components. To attenuate the secondary neutron flux over 300 g/cm2 of atmospheric material is required. The numerous slow protons from nuclear interactions in shielding will also genetrate upsets in sensitive components, which have a low critical charge. At altitudes below 65,000 feet, most single-event upsets are due to these secondary particles. The upset rates due to neutrons and slow secondary protons from cosmic ray, solar flare particle, and trapped radiation particle interactions are presented as a function of the critical charge.