Preliminary study of sample uniformity impact on the elemental analysis in PGNAA technique

Background: In the adoption of Prompt Gamma-ray Neutron Activation Analysis (PGNAA) technique, the composition of samples is always assumed to be uniform, while it is nonuniform in fact, which would affect the analysis result. Purpose: The influence of the sample's uniformity, to PGNAA has been discussed. Methods: Samples of the same composition and average density, but different uniformity have been simulated with Monte Carlo method. And the preliminary analysis has been discussed in the aspects of self-absorption and the neutron field distribution of the samples. Results: The results show that the change of sample uniformity. has a certain effect on the gamma-rays spectrum. The difference of the element characteristic peak counting rate, which is caused by the change of samples' uniformity, is even higher than 20% for some elements. Conclusion: In the PGNAA technique, the uniformity of samples has to be considered to ensure the element analysis accuracy. (authors)