A SCINTILLATION DETECTOR SIGNAL-PROCESSING TECHNIQUE WITH ACTIVE PILEUP PREVENTION FOR EXTENDING SCINTILLATION COUNT RATES

A new method for processing signals from scintillation detectors is pr oposed for very high count-rate situations where multiple-event pileup s are the norm. This method is designed to sort out and recover every impinging event from multiple-event pileups while maximizing the colle ction of scintillation signal for every event to achieve optimal accur acy in determining the energy of the event. For every detected event, this method cancels the remnant signals from previous events, and excl udes the pileup of signals from following events. With this technique, pileup events can be recovered and the energy of every recovered even t can be optimally measured despite multiple pileups. A prototype circ uit demonstrated that the maximum count rates have been increased by m ore than IO times, comparing to the standard pulse-shaping method, whi le the energy resolution is as good as that of the pulse shaping (or t he fixed integration) method at normal count rates. At 2x10(6) events/ sec for NaI(T1), the true counts acquired are 3 times more than the de lay-line clipping method (commonly used in fast processing designs) du e to events recovered from pileups. Pulse-height spectra up to 3.5x10( 6) events/sec have been studied.