783620H / 1013 6. ANALYSIS METHODS
tively, the number of half-lives can be set in b30winds.ini
; see Section A.2.2). If the time is greater than 12 half-lives, the correction is not made and the message is printed out. Twelve halflives corresponds to a decay factor of about 4000. Both the time of count and decay-corrected values are presented on the report. The total activity is the decay-corrected activity.
Decay correction is determined as follows:
(83)
where
ΔT = T
Count
! T
Collection
6.10.3. Decay During Collection
If the sample was collected over an extended time (see page 155), this correction will account for the buildup or increase of activity in the sample during the collection time. The correction is given by:
(84)
6.10.4. Peaked Background Correction
The Peaked Background Correction (PBC) is used to correct for the presence of peaks in the background spectrum that also occurs in the sample. If the peak is not of interest in the analysis results, there is no need to make this correction. The values in the PBC table are the counts per second at each library energy. These count rates are multiplied by the sample live time to calculate background counts, and the resulting background counts are added to the respective peak background. Note that this background subtraction may raise the peak uncertainty above the
peak cutoff such that a peak is no longer considered as identified.
This section describes how peaks are qualified for PBC correction. The correction and uncertainty calculations are covered in Section 6.12.12.
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