Implications for analysis of ²²⁶Ra in a low-level gamma spectrometry laboratory due to variations in radon background levels

The background spectrum of HPGe detectors is found to vary significantly as function of the radon concentration in the air surrounding it, especially with regard to the count rates of ²²²Rn daughter peaks. This effect is shown to potentially have a large impact on measured values of radon daughter activity concentration, as well as detection limits for low-level measurements. As these radionuclides are commonly used for estimating the activity of ²²⁶Ra, care needs to be taken to ensure that background levels are accurately determined. - Highlights: • Effects of temporal radon variations in a gamma spectrometry laboratory have been studied. • Measurements of ²²⁶Ra from its progeny may be significantly disturbed. • For a case of low-level sediments, errors of more than 100% are observed. • Minimum detectable activities may be over- or underestimated by 30–60%. • Accurate background determination is crucial to avoid measurement errors