Sampling requirements of discrete wavelet transform (DWT) method for n-γ discrimination by liquid scintillators

다국어 초록 (Multilingual Abstract)

The efficacy of pulse shape discrimination (PSD) methods for distinguishing between neutrons and γ-rays using liquid scintillators is significantly impacted by the sampling characteristics of fast waveform digitizers. This study specifically delves into investigating the digitization prerequisites of the discrete wavelet transforms (DWT) method, utilizing digitized pulses obtained from an experimental mixed radiation field comprising neutron and γ-ray events from AmBe source with an energy threshold of 250 keVee, collected by BC501A liquid scintillator.
The DWT method has been optimized to determine processing gate duration and the form of discrimination parameter for various sampling rates ranging from 250 MS/s to 2.5 GS/s. The performance of the DWT method is compared with the Charge Comparison (CC) method in terms of the figure of merit (FoM). Notably, the DWT method outperforms the CC method at 250 MS/s with a 12-bit Analog-to-Digital Converter (ADC), when the digitized pulses are processed for a short processing gate of 46 ns. This attribute of the DWT method proves advantageous in high-count rate environments where pulse-tail contamination by pile-up events occurs more frequently. Furthermore, to achieve a FoM greater than unity for the radiation field with energy threshold of 250 keVee, a maximum sampling rate of 500 MS/s suffices for the DWT method