Electronics and signal processing for prompt radiation

Active interrogation with pulsed bremsstrahlung beams can saturate detectors and produce high count rates of overlapping pulses in the prompt region (<1 mus) after the interrogating pulse. We describe a method to eliminate saturation by modifying the photomultiplier voltage divider and by gating intermediate pairs of dynodes and the anode. To process the high count rate of overlapping pulses, we convert the output current pulses to charge-pulse steps that can be digitally processed more easily and rapidly in real time. We discuss the application to LaBr₃, liquid, and plastic scintillators and present some preliminary data.