Concepts, Instrumentation and Techniques of Neutron Activation Analysis

Abstract

Nowadays, there are many elemental analysis methods that use chemical, physical and nuclear characteristics. However, a particular method may be favoured for a specific task, depending on the purpose. Neutron activation analysis (NAA) is very useful as sensitive analytical technique for performing both qualitative and quantitative multielemental analysis of major, minor and traces components in variety of terrestrial samples and extra-terrestrial materials. In addition, because of its accuracy and reliability, NAA is generally recognized as the "referee method" of choice when new procedures are being developed or when other methods yield results that do not agree. It is usually used as an important reference for other analysis methods. Worldwide application of NAA is so widespread it is estimated that approximately 100,000 samples undergo analysis each year. The method is based on conversion of stable atomic nuclei into radioactive nuclei by irradiation with neutrons and subsequent detection of the radiation emitted by the radioactive nuclei and its identification. The basic essentials required to carry out an analysis of samples by NAA are a source of neutrons, instrumentation suitable for detecting gamma rays, and a detailed knowledge of the reactions that occur when neutrons interact with target nuclei. Brief descriptions of the NAA method, reactor neutron sources, and gammaray detection are given below.

Overview of Neutron Activation Analysis

“…Gamma-ray intensity is proportional to the element content in the sample. Instrumental neutron activation analysis (INAA) and k 0 -INAA are the most sensitive analytical techniques used for the quantitative multielement analysis of major, minor, and trace elements in samples from almost every conceivable field of scientific or technical interest [1][2][3][4][5][6][7][8][9].…”

Colombian Neutron Activation Analysis Laboratory (CNAAL): Applications and Development Using the Nuclear Research Reactor IAN-R1

“…The elemental determination in the NAA is done by using the relative calibration (direct comparator method) [20]. This method uses a sample with known mass of the elements of interest (comparator or standard) and an unknown sample which is irradiated simultaneously.…”

Estudo de técnicas estatísticas aplicadas à determinação de parâmetros no método <i>k₀</i> de análise por ativação neutrônica

“…Entretanto, ela é restrita para reações (n, ) nas quais o fator de Westcott é igual à unidade [5,40,41] . Em situações em que difere da unidade, recomenda-se não utilizar a convenção de Høgdahl e considerar a temperatura do nêutron, o que, em outras palavras, significa utilizar o formalismo de Westcott [35,[42][43][44] . Ao longo dos anos, adaptações foram feitas em ambas convenções [32,36,41,44,45] .…”