Contribution of Secondary Alpha Particles to Soft Error Rates in Space Systems

The importance of including secondary particles in particle environments for single event effects (SEE) simulations is examined by comparing total error rates with and without secondary alpha particles as a result of target fragmentation. Previous experimental single-event tests have demonstrated importance of short-range, high-LET secondary particles, produced by target fragmentation near to device. However, current error rate prediction workflows, based on tools such as CREME96 and SPENVIS, do not account for these secondary particles from target fragmentation. Reevaluating those practices shows that the impact of secondary alpha particles on total error rates is negligible for the environments, devices, and aluminum shielding explored. To compare the broader issue of nuclear reactions in overlaying materials, energy deposition simulations were done in MRED, which indicate that the composition and sequence of overlying materials need to be considered with regard to secondary particle production.