The SEU figure of merit and proton upset rate calculations

This paper re-examines the use of the SEU Figure of Merit for heavy ion upset rate predictions. Slightly different orbit dependent rate coefficients are used for unhardened and hardened parts. The two different coefficients allow for the slight changes of LET spectra that occur due to the Earth's magnetic shielding. Accurate heavy ion predictions can be made for any orbit and any part. We show that the Figure of Merit can also be used to predict upset rate due to protons in the proton radiation belt. A proton rate coefficient is introduced to describe the upset likelihood in orbits with proton exposures. These results mean that a part susceptibility can be described by a single parameter, rather than the four Weibull parameters and two Bendel parameters used previously. The Figure of Merit completely describes a part's SEU susceptibility and can be obtained from either proton or heavy ion measurements, eliminating the expense of making both types of experiment. The total upset rate for a part in a particular orbit can be calculated using its characteristic Figure of Merit and a single orbit specific rate coefficient, the sum of the heavy ion and proton rate coefficients.