Sparsity-based pulse-processor for digital α-particle spectroscopy with Si-PIN-Diode detector.

Nowadays, digital methods are used in nuclear detection instruments which are more popular than conventional signal processing. In this work, a digital α-particle spectrometer, compatible with the low-cost digitizers, was designed and constructed. Similar to the analog pulse-height analyses, the digital signals must also be carefully shaped. Here, the charge pulses induced by alpha particles were measured in a silicon PIN-diode detector. Then, a digital sparsity-based pulse-processor was introduced for shaping the charge signals that were digitized by a low sampling rate digitizer. To this end, a charge-sensitive pre-amplifier was designed and fabricated for coupling to the digitizers. To perform off-line analysis, the detector pulses were stored through a combination of a fast-digital oscilloscope and the LabVIEW software. Finally, the pulse-height spectrum was obtained by a digital multi-channel analyzer block. The performance of the designed filter was examined for Ra-226 alpha spectrum by comparing its output with those of other conventional filters. Our results show the advantages of the sparsity-based filter in high-resolution measurements. The designed filter achieved an energy resolution of 12.3% at 4.78 MeV alpha particles.