Energy-resolved coincidence counting using an FPGA for nuclear lifetime experiments

With the increasing availability of single-board computers equipped with fast analog-to-digital converters based on field-programmable gate arrays (FPGA), researchers and educators gain access to relatively inexpensive hardware that can be programmed for advanced coincidence counting. We demonstrate this capability by developing software for a dual-channel open-source data acquisition platform, enabling it to perform energy- and time-resolved coincidence counting and testing our system using an ²⁴¹Am source. Measuring the coincidence between alpha and gamma radiation allowed us to determine the half-life of the ²³⁷Np excited state. The obtained value of 67.7 ± 0.1 ns is compatible with the value cited in the literature. Furthermore, the use of digital signal processing enabled us to sort time-resolved counts by alpha and gamma energy, which resulted in additional information on the decay scheme. Correlation heatmaps between the two spectra were plotted and used to verify the decay scheme. The half-lives of the other features visible in the gamma spectrum were determined as well.