The relationship of proton and heavy ion upset thresholds

A method of obtaining proton upset thresholds from heavy ion upset thresholds, and vice versa, is presented. Specifically, a simple relationship between the heavy ion LET (linear energy transfer) threshold for upset and the threshold for proton-induced upsets as described by the Bendel A parameter (A = L0.1 + 15) is given. This relationship will enable either proton or heavy ion laboratory measurements to be used for estimating upset rates for both types of particles in space environments. Calculation of upset rates based on LET thresholds indicates that, for some orbits in the proton radiation belt, devices with thresholds of 10 to 45 MeV/mg/cm2 might produce unacceptable proton upset rates. The proton upsets for devices with thresholds above 10 MeV/mg/cm2 are caused by relatively rare reaction processes that occur at high proton energies.