Analog Pulse Shape Discrimination Circuit for High Event Rates and Fast Scintillators with a Dynamic Deadtime

Abstract

We developed an analog pulse shape discrimination (PSD) topology based on the well-established charge integration (CI) method, featuring two novel functional blocks beneficial for high event rate operation. The topology is designed for high-speed scintillators. The demonstrated analog design is potentially better suited than digital methods, when considering both processing time and power consumption aspects. The topology was tested using both experimental alpha and beta pulses from a plastic scintillator with a layer of ZnS(Ag) coupled to a PMT, and a fast digital emulator to simulate controlled high event rate scenarios. The discrimination capabilities of the topology were optimized and evaluated using a traditional figure of merit (FoM) approach. The topology achieved over 99% correct classifications when evaluated using the experimental pulses recorded. Additionally, the dedicated blocks resulted in a fourfold reduction in miss-classifications of slow pulses at an event rate of 100 kcps of fast pulses, while also providing a dynamic deadtime proportional to the pulse charge.