Nuclear Science and Techniques

Abstract: Optimization algorithms are applied to resolve the second-order pileup (SOP) issue from high counting rates occurring in digital alpha spectroscopy. These are antlion optimizer (ALO) and particle swarm optimization (PSO) algorithms. Both optimization algorithms are coupled to one of the three proposed peak finder algorithms. Three custom time-domain algorithms are proposed for retrieving SOP peaks, namely peak seek, slope tangent, and fast array algorithms. In addition, an average combinational algorithm is applied. The time occurrence of the retrieved peaks is tested for an elimination of illusive pulses. Conventional methods are inaccurate and timeconsuming. ALO and PSO optimizations are used for the localization of retrieved peaks. Optimum cost values that achieve the best fitness values are demonstrated. Thus, the optimum positions of the detected peak heights are achieved. Evaluation metrics of the optimized algorithms and their influences on the retrieved peaks parameters are established. Comparisons among such algorithms are investigated, and the algorithms are inspected in terms of their computational time and average error. The peak seek algorithm achieves the lowest average computational error for pulse parameters (amplitude and position). However, the fast array algorithm introduces the largest average error for pulse parameters. In addition, the peak seek algorithm coupled with an ALO or PSO algorithm is observed to realize a better performance in terms of the optimum cost and computational time. By contrast, the performance of the peak seek recovery algorithm is improved using the PSO. Furthermore, the computational time of the peak optimization using the PSO is much better than that of the ALO algorithm. As a final conclusion, the accuracy of the peaks detected by the PSO surpasses that for the peaks detected by the ALO. The implemented peak retrieval algorithms are validated through a comparison with experimental results from previous studies. The proposed algorithms achieve a notable precision for compensation of the SOP peaks within the alpha ray spectroscopy at a high counting rate.

Key words: Alpha spectrometry instrument, Second-order pileup, Signal processing, Optimization algorithms