Minimum Detectable Concentration and Concentration Calculations

Radioxenon net count calculations revisited

“…Using an appropriate statistical model will become more important as systems become more sensitive. Developers need to provide operators their specific analysis implementation (e.g., as has been provided for some systems [1,12]), including estimated statistical and systematic uncertainties. While standardization is desirable, it should not prohibit advancements.…”

“…In the 7-ROI approach [12], used by Xenon International, the number of regions has been minimized to provide a simple, yet robust, analysis framework. The ROIs for 135 Xe and 133 Xe (80 keV) in this approach are generally distinct and straightforward to analyze.…”

“…(1) and (2) are generalized and do not rigorously show all correction factors. The calculation of the net counts is described meticulously in [11,12]. First, one must handle the dependent variables, such as counts from the detector background, correctly.…”

“…The branching ratio for a given isotope are for the particular γ-or x-ray decay energy that is observed in the isotope ROI. This general equation is described in more detail in a number of publications [9][10][11][12]. This paper focuses on systems that use β-γ coincidence to calculate radioxenon concentrations, in particular, the Swedish Automatic Unit for Noble gas Acquisition (SAUNA II) [13], developed by the Swedish Defense Research Agency (FOI) [14], the Xenon International [4,15], developed by the US Department of Energy's Pacific Northwest National Laboratory [16], new generation SPALAX system (Si + HPGe) [17,18], and ARIX-4 system [19].…”

“…where the net counts are determined from the total counts in the ROI from the sample ( Counts Gross ) minus the contributions from the background ( Counts Background ), interferences from other isotopes present in the sample ( Counts Interference ), and the memory effect ( Counts Memory ). Explicit equations for all ROIs can be found in [12] for one approach (7-ROI), and in [1,11,20] for another approach (10-ROI). The differences between these two approaches will be described, including the impact of the ROI on the gross counts term.…”