GammaVision
®
v7 (A66-BW) 783620H / 1013
where
σ
A
is the nuclide activity. If
σ
A
is still zero, then the gross counts under the peak is calculated and the area uncertainty determined as:
(213)
where G is the gross counts under the peak, and
σ
B
2
is the peak background uncertainty calculated from Eq. 144 or by methods in Section 6.17.7.1. In some cases, because the variance of the background is G (see Eq. 200), the right side of Eq. 213 simply becomes twice the gross counts.
6.18. EDF Gamma Total Analysis
6.18.1. Geometry (K-Factor) Calculation
1) Measure the background between 100 keV and 2 MeV.
2) Calculate the K coefficient, based on the measurement of a
137
Cs source, as follows:
(214)
where
K
= K coefficient
T
R
A s
A g
= Real time, in seconds
= Source activity at the time of measurement, in Bq
= Gross area between the chosen range of the source spectrum (100 keV–2 MeV),
A bkg
in counts
= Gross area between the chosen range of the background spectrum
(100 keV–2 MeV), in counts. Choose the background spectrum on the Gamma
Total setup dialog (Section 5.5.1.9).
330
