Development of the internal standard method in NAA at the Dalat research reactor

The k0-standardization INAA method has recently developed and applied for analysis of geological, biological and environmental samples at the Dalat research reactor. To enhance the analytical capability, a k0-based internal monostandard INAA method (k0-IM-NAA) has been investigated for determination of elemental concentration in samples of large size and non-standard geometry. In this method, one of the elements present in the sample is used as an internal monostandard and the relative efficiency could be obtained by using γ-rays of the activation products in the sample itself in order to correct the γ-ray self-attenuation and geometrical effects. Three Standard Reference Materials of SMELS III, Montana II Soil (SRM 2711a) and Brick Clay (SRM 679) have been used to validate the method. The accuracy of the method was evaluated using u-score and % deviation. The k0-IM-NAA method has been applied to determine the elemental concentrations in the clay bricks at Cat Tien archaeological site.