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.