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NAA General Principles

In typical NAA, stable nuclides (AZ, the target nucleus) in the sample undergo neutron capture reactions in a flux of (incident) neutrons. The radioactive nuclides (A+1Z, the compound nucleus) produced in this activation process will, in most cases, decay through the emission of a beta particle (β-) and gamma ray(s) with a unique half-life. A high-resolution gamma-ray spectrometer is used to detect these "delayed" gamma rays from the artificially induced radioactivity in the sample for both qualitative and quantitative analysis.

Sequence of events that occur during the most common type
of nuclear reaction used for activation analysis
NAA schematic

An example of the gamma-ray spectrum from the activation of a human nail used as a biological monitor of trace-element status is shown below.

NAA schematic
NAA Main | NAA General | NAA Analytical Signal | NAA Quantification | NAA Advantages and Limitations