Improving performance of fast high resolution LaBr3 scintillation detectors in case of pulse pile-up effects

Pulse pile-up, even at moderate rate of incoming events (20-30 kcps) can significantly degrade the performance of Lanthanum bromide (LaBr₃) scintillators with respect to their very good energy resolution. A working array of 10 large LaBr₃ detectors is available in Milano and we are currently going to improve the existing associated electronics for acquisition and data processing. As a first step, we evaluated the performance and compared advantages and drawbacks of using free running analog to digital converters (ADCs) and subsequent digital signal processing versus the more traditional technique based on analog signal shaping and peak sensing ADCs. The main goal of the optimization process is to preserve the excellent performance of LaBr₃ detectors not only in controlled laboratory condition, but also during the experimental campaigns. In this work we analyze, estimate and experimentally measure the effect of pulse pile-up for LaBr₃ scintillators with respect to the acquisition and processing electronics (analog or digital), for various counting rate of events. Significant improvements are achieved, both for the analog and digital approach and the associated results are presented.