5 1st peak Ni ions 1st peak 2nd peak signals Levourd ......... and mm 10° 10 1 102 10 3 10 4 10 5 106 6 Collected Charge [pC] Figure 4.9. Illustration of energetic particle induced charge spectroscopy (EPICS) technique for measuring single-event burnout [218]. II-44 Many other studies of SEB have been performed; not all of them can be summarized here. These include studies of the position-dependence of SEB [219], temperature-dependence of SEB [220], and hardening strategies [221-223]. The interested reader is directed to references [212- 223] and references therein for further information. II-45 MODELING AND SIMULATION OF SINGLE-EVENT MECHANISMS From the earliest history of numerical device modeling, the radiation effects community has recognized the value of computational modeling for providing insight into the effects of ionizing radiation on microelectronic devices. In fact, pioneering work on one-dimensional drift-diffusion numerical modeling was presented at the Nuclear and Space Radiation Effects Conference as early as 1967 [224,225], winning the Best Paper award for that year [224]. This early work focused on transient radiation response, as single-event upset (SEU) would not be observed experimentally until almost 10 years later [226]. Given the consequences of SEU (potential loss of mission for space applications, a possible show-stopper for increased integration density in terrestrial memory cells), the rapid development of models to explain and predict radiation effects was essential. The development and use of numerical models for radiation effects has proceeded on many levels: the interaction of ionizing particles with matter, physical device simulators that predict the response of devices to incident radiation, circuit simulators that model circuit response to a single event, and codes that predict the error rate that will be observed for a specific part flying in particular orbit. In this short course segment we will only discuss the models that most directly pertain to the actual upset process its