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 ups et rate predictions Slightly different orbit dependent rate coefficients ar e used for unhardened and hardened parts. The two different coefficients al low for the slight changes of LET spectra that occur due to the earth's mag netic shielding. Accurate heavy ion predictions can be made for any orbit a nd 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 intr oduced to describe the upset likelihood in orbits with proton exposures. Th ese results mean that a part susceptibility can be described by a single pa rameter, rather than the four Weibull parameters and two Bendel parameters used previously. The Figure of Merit completely describes a part's SEU susc eptibility 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 usi ng its characteristic Figure of Merit and a single orbit specific rate coef ficient, the sum of the heavy ion and proton rate coefficients.