Pulse Shape Discrimination with a Low-cost Digitizer Using Commercial Off-the-shelf Components

Pulse shape discrimination of neutrons and gammas is demonstrated using a FemtoDAQ, a low-cost digitizer that uses commercial off-the-shelf components. This digitizer is paired with a CLYC scintillator coupled to a photomultiplier tube to concurrently detect neutrons and gammas. Python code was written to analyze the detector waveforms to determine the energy deposited and distinguish neutron and gamma events within the CLYC crystal. The energy of each waveform is determined by the summation of the discrete amplitudes recorded by the digitizer for each pulse. This method is compared to a traditional multichannel analyzer operating with commercial software for validation and shown to produce the same energy spectrum. Pulse shape discrimination is accomplished by measuring and summing the amplitudes of the prompt portion of each waveform (first 80 ns) and the delayed portion (following 500 ns) and then calculating a ratio of the delayed region to the total. This technique was able to clearly distinguish thermal neutron events from gamma events with a figure of merit of 1.42