Extraordinary improvement in scintillation detectors via post-processing with ASEDRA: solution to a 50-year-old problem

Abstract

We have developed a ground-breaking algorithm, ASEDRA, to post-process scintillator detector spectra to render photopeaks with high accuracy. The post-processed spectrum is comparable with resolved full energy peaks rendered by high resolution HPGe semiconductor detectors. ASEDRA, or "Advanced Synthetically Enhanced Detector Resolution Algorithm," is currently applied to NaI(Tl) detectors, which are robust, but suffer from poor energy resolution. ASEDRA rapidly post-processes a NaI(Tl) detector spectrum over a few seconds on a standard laptop without prior knowledge of sources or spectrum features. ASEDRA incorporates a novel denoising algorithm based on an adaptive Chi-square methodology called ACHIP, or "Adaptive Chi-quare Processed denoising." Application of ACHIP is necessary to remove stochastic noise, yet preserve fine detail, and can be used as an independent tool for general noise reduction. Following noise removal, ASEDRA sequentially employs an adaptive detector response algorithm to remove the spectrum attributed to specific gammas. Tests conducted using a 2"×2" NaI(Tl) detector, along with a HPGe detector demonstrate the accuracy of ASEDRA; in this paper, we present results using a 152Eu source. Analysis of ASEDRA results show correct identification of at least 15 photopeaks from ¹⁵²Eu, with relative yield ratios of major lines to better than a factor of two for most cases (referencing the ¹⁵²Eu 344 keV photopeak), enabling better than a factor of four improvement in resolving peaks compared with unprocessed NaI(Tl). Moreover, denoising and synthetic resolution enhancement algorithms can be adapted to any detector. ACHIP and ASEDRA are covered under a Provisional Patent, Registration Number #60/971,770, 9/12/2007, USPTO.