Absolute Method for a Single Element

If the irradiated sample is placed at distance r from the detector of area Da, the induced activity A of the radioisotope formed in the sample, with N 

The weight (m) of the unknown element in the sample can thus be calculated from (6.4). Apart from the counting statistics, the total error in NAA depends on a number of factors like sample preparation, weighing, and uncertainty in the basic parameters and amounts to 10%. This error can, however, be reduced by the comparison method described in Subsect. 6.4.2. 

---