Influence of Short Lived Radon and Thoron Progeny on the Γ-Spectroscopic Analysis of Low Activity Environmental and Aerosol Samples

In this work, the influence of radon and thoron progeny photons in γ-spectrometry analysis is thoroughly investigated. To this end three sampling and analysis campaigns were organized at the γ-spectrometry laboratory of Nuclear Engineering Laboratory of the National Technical University of Athens (NEL-NTUA), combining measurements of radon and its progeny via an ALPHAGUARD-ALPHAPM set up with background spectra of four germanium detectors as well as with outdoors meteorological conditions. Good statistical correlations were found between radon and its progeny with the respective photopeaks of the germanium detectors’ background as well as with meteorological conditions outdoors. Additionally, in all four detectors, six consecutive 2-day background spectra were compared with each other, with their mean and with the summed 12-day background spectrum, in order to study the photopeak background fluctuation and estimate the relevant uncertainties. This study supported the decision for the most suitable background spectrum to be used in γ-spectrometry analysis. Finally, in order to investigate the effect of both radon and thoron progeny on the MDA of typical radionuclides likely to be detected in aerosol samples, a series of air-sampling and γ-spectroscopic analysis scenarios were tested.