Correlation of Pulsed-Laser Energy and Heavy-Ion LET by Matching Analog SET Ensemble Signatures and Digital SET Thresholds

The quantitative correlation between the incident energy of a laser pulse and the Linear Energy Transfer (LET) of a heavy-ion beam is verified up to very high energy levels, by comparing the scatter plots of amplitude vs. duration of ensembles of Analog Single Event Transients (ASETs) generated with both methods in a complex CMOS RadHard Analog-to-Digital Converter (ADC). The same energy correlation is then confirmed in a more traditional way, by matching the onset energy thresholds of Digital SETs (DSETs) of a comparator-based voltage supervisor circuit. The observed dependency of the upset threshold on the circuit response time leads to a more general discussion of the influence that laser pulse-widths have on the SET sensitivity of mixed-signal circuits. Preliminary to this study, the energy of the laser apparatus at the Aeroflex facility was aligned to that of the NRL laser by comparing the transient shapes produced when a p-n photodiode, previously used for similar comparison purposes, was irradiated.