  A simple and self-consistent approach has been proposed for simulation of the
proton-induced soft error rate based on the heavy ion induced single event
upset cross-section data and vice versa. The approach relies on the GEANT4
assisted Monte Carlo simulation of the secondary particle LET spectra produced
by nuclear interactions. The method has been validated with the relevant
in-flight soft error rate data for space protons and heavy ions. An approximate
analytical relation is proposed and validated for a fast recalculation between
the two types of experimental data.
