Study of gamma background fluctuations and its associated uncertainty in naturally occurring radioactive material activity estimation using a shielded HPGe detector

Environmental radioactivity measurements deal with very low activity levels, making it challenging, especially under high background conditions. This problem is more prominent for gamma spectrometric measurements of naturally occurring radioactive material (NORM). Extensive studies have been done previously to achieve reasonable MDA values and precision in the reported activity values. In the present study, the gamma background fluctuations of the shielded 30% HPGe detector at our lab are studied for different counting times, and its correlation with the overall uncertainty of NORM estimations is depicted.