GammaVision
®
v7 (A66-BW) 783620H / 1013
6.12.12. Peaked Background Correction and Uncertainty Calculations
6.12.12.1. Single PBC Subtraction
If the PBC net count rate at energy E is R
p
(in cps), the live time is LT (in seconds), and the fractional uncertainty of the net PBC peak count rate is
σ and the associated absolute uncertainty
σ
absp p
, then the corresponding PBC counts N
in counts can be calculated from the following:
p
(129)
(130)
If N
0
is the peak area in counts before PBC,
σ
0
is the corresponding fractional uncertainty, and
σ
abs0
is the corresponding absolute uncertainty for the net peak area before PBC (see Eq. 48, page 250), the absolute peak area uncertainty before PBC is:
(131)
The PBC corrected peak area N (in counts) is calculated as:
(132)
If, after PBC, the net peak area is <0, it is set to 0 unless Directed Fit is enabled (because negative peak area is not physical). After PBC, the subtracted PBC area is added to the peak background. If B
0
is the peak background before PBC, the peak background after PBC is:
(133)
After PBC, the variance of the peak net area counts has contributions from the PBC subtraction as well as from the change in the peak background discussed above. The variance from the PBC subtraction is simply
σ
absp
2
.
304
