Determination of Minimum Detectable Activity (MDA) for AT1315 Gamma Spectrometer

The minimum detectable activity (MDA) is the activity that a system can detect with a given confidence level and good discrimination against the background radiation. When low levels of activities are counted, the MDA of gamma spectrometer must be comparable to the number of sample counts. In this research, the MDA of AT1315 spectrometer has been experimentally determined and a theoretical correlation between the MDA and experimental parameters such as the sample mass and counting time has been established. Using the correlation, the frequent and cumbersome MDA measurements can be avoided. A quantitative comparison of the theoretical and experimental MDA approaches has been performed.