und in the references provided. In general, even if knowledge of a thin epitaxial material suggests latch-up immunity, latch-up testing should be performed prior to consideration for flight application when the process under question is not well known. Heavy ion screening would be a first step with proton latch-up testing advised only if the heavy ion threshold were low and there was a need to quantify the risk in a proton rich environment. In practice, most missions would avoid the use any part susceptible to failure by proton-induced latch-up for a critical application based on the risk to heavy ion induced failure alone. 4.3.2 Proton-induced Single Event Burnout (SEB) in Power MOSFETs: Single event burnout occurs when an ion or proton-induced recoil atom strikes a power MOSFET in its "off" state and triggers a parasitic bipolar junction transistor. This "on" transistor creates a conduction path between source and drain, and the resulting regenerative feedback leads to a high current state causing second breakdown and burnout. Single event burnout in power MOSFETs has received considerable attention as a hard failure mode from heavy ion effects [Titu-96, Alle-96, Ober-96, Adol-96, and references therein]. Recently, as was the case with latch-up, both experimental investigations and in-flight experience have pointed to protons as a possible cause for burnout. Two 1996 NSREC papers addressed this issue, one with laboratory measurements [Ober-96] and the other with flight data [Adol-96]. Oberg and co-authors evaluated the response of power MOSFETs to both high-energy proton and to high energy neutron irradiation [Ober-96]. Their evidence indicated some correlation between proton SEB cross sections and those for neutrons and heavy ions, with the IV-40 more energetic protons being more likely to cause burnout. The flight data from the CRUX experiment [Adol-96] both confirmed the effect for orbital protons and showed it to be more likely on the higher voltage (200 V) device, as expected. Figure 20 shows additional fl