783620H / 1013 6. ANALYSIS METHODS
6.7. Nuclide Activity
The nuclide activity is calculated for all peaks in the library whose energy is between the energy limits you have selected for the analysis (in-range). There are several methods of determining if a nuclide is present or not, and if MDA should be reported.
A nuclide is reported with an activity value under the following conditions:
1) If more than one peak is listed for the nuclide, the following apply:
! The first in-range peak that is not marked as “Not in Average” and not closely overlapping another library peak, such that peak stripping would be applied, must be identified.
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! All peaks marked as key lines must be identified.
! The Fraction Limit Test must be satisfied.
! For GAM32 and ENV32, the Library Reduction requirements must be satisfied (ee
Section 6.2.3.)
2) If only one peak is listed for the nuclide, the following apply:
! If the peak does not closely overlap another library peak, it must identified in the analysis range.
! If the “Not in Average” flag is set for this peak, the nuclide is automatically rejected when using all analysis engines except for WAN32, which ignores the “Not in Average” flag under this condition.
! If the peak closely overlaps another library peak such that peak stripping would be applied, the uncertainty of the area remaining after peak stripping must be less than the
Peak Cutoff.
3) Directed Fit forces an activity to be reported for nuclides that do not meet the preceding criteria.
If a nuclide is not reported with an activity value, and the “No MDA Calculation” flag is not set in the library, the MDA value will be reported in the Summary of Nuclides in Sample. Otherwise, the nuclide will be omitted from the Summary of Nuclides in Sample.
The nuclide activity (in becquerels or curies), based on the peak at energy E, is given by:
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“Identified” in this discussion indicates the peak counting uncertainty at 1 sigma is less than the Peak Cutoff value.
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