Proton SEU rate predictions

Charge collection measurements show that proton-induced elastic interactions can dominate the production of SEUs in certain COTS parts when the value of the critical charge is sufficiently low. In the bulk device used in these measurements, the elastic recoils do not introduce any angular dependence nor are they energetic enough to upset the device. The spallation reactions should not introduce an angular dependence either because of the shape of the sensitive volume. However, an increase in charge-collection events is observed at very large angles of incidence, beginning at 78/spl deg/. This increase appears to be caused by secondary particles generated in the side walls of the chip's packaging, and this contribution would be significant for SEU production in devices with low values of the critical charge but not for those with large values.