6.12.7.2. TCC-Polynomial. ORTEC A66-BW GammaVision

783620H / 1013 6. ANALYSIS METHODS

where N2 is the number of calibration peaks with energies less than the knee energy. If N2 is zero, the counting uncertainty is zero.

For polynomial and TCC-polynomial type calibrations, the calibration counting uncertainty

σ

p

is always equal to the counting uncertainty above the knee:

(102)

For all other calibration types,

σ

p

is calculated as:

(103)

NOTE

For calibrations performed before GammaVision 7, the above-and below-the-knee counting uncertainties are both zero. To take into account the counting uncertainty discussed here, update the efficiency calibration with GammaVision 7 so the new uncertainties will be calculated and stored in the calibration file. Then, when a spectrum is analyzed, the final reported activity uncertainty will take into account the added uncertainty in calibration.

6.12.7.2. TCC-Polynomial

The calibration variance is the averaged variance of all the calibration points in the certificate file:

(104)

where:

σ

C

σ

i

= the calibration uncertainty

= the uncertainty of the i th

calibration point from the certificate

N

= the total number of calibration points

6.12.7.3. Interpolative

For this calculation, the calibration points are sorted in ascending order by energy. If energy E is less than the first (lowest-energy) calibration point, E

i

and E

i+1

are the two lowest-energy calibra-

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