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where N
MDA
is LD
Net
in Eq. 162; and the parameters b, c, and v are defined as:
6. ANALYSIS METHODS
(163)
(164)
(165)
(166)
where N
CL
, the critical level in counts, is SD conversion factor, is
σ%
R
Net
in Eq. 162; µ%
R
, the uncertainty of the activity
in Eq. 162; and all other parameters have been defined above.
Comparing Eq. 163 to the original MDA equation Eq. 162, one sees that b is the first two terms in the numerator, c is the correction term in the denominator, and v is the operand inside the square-root operator. The identities above are used in the following sections.
Uncertainties in the MDA Equation
The uncertainty of the conversion factor takes into account the calibration efficiency uncertainty, nuclide uncertainty, additional random uncertainty, additional systematic uncertainty, and geometry correction uncertainty (if the geometry correction is turned on and the uncertainty is a fixed value of 1.5%). The equation used to calculate µ%
R
is:
(167)
where:
σ
σ
σ
σ
σ
eff
2 geo
2 nuc
2 nor
2 rsum
2
= efficiency uncertainty estimate (Section 6.12.7).
= nuclide uncertainty estimate (Section 6.12.6)
= additional normally distributed uncertainty estimate (Section 6.12.3)
= geometry uncertainty estimate (Section 6.12.8)
= random summing uncertainty estimate (Section 6.12.4)
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