Single event phenomena (SEP) are effects resulting from a single particle inducing a significant response in an integrated circuit. SEP are of greatest concern to spacecraft designers but are becoming of concern to avionics and large earth-bound electronic systems due to the continual reduction in size (which increases SEP sensitivity) of circuit elements. The phenomena include soft error and multiple errors in memory cells or logic latches, latchup, MOSFET power device burnout, MNOS punch-through and transients. Cyclotron and Van de Graaff accelerators are used to produce heavy ions, protons and neutrons which induce SEP effects. Methods of testing are described. Solutions to SEP are varied, but include parts substitutions or redesign and software solutions which will be described.