Neutron activation analysis based on instant radiation

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Neutron activation analysis based on instantaneous radiation (PGAA, PGNAA, prompt gamma-ray neutron activation analysis) - a neutron activation assay (NAA) consisting of placing the test sample in a neutron beam (thermal or cold) and recording emitted radiation gamma. Principle of analysis

Atomic nuclei of the elements contained in the sample absorb neutrons with the probability determined by the cross-section, while emitting gamma quanta. The energy of the emitted radiation determines what elements are present in the sample, and its intensity corresponds to the mass of the element in the sample. Radiated radiation is recorded by a gamma-ray detector, typically a germanium detector. Its energy is up to 10 MeV (in the reaction of neutron capture by the N nucleus is emitted gamma quantum with energy of 10.8 MeV), whereas the radiation energy emitted in natural radioactivity degradation in practice does not exceed 3 MeV (for example, Tl is 2.614 MeV) . The basic difference in comparison to classical activation analysis is the recording of radiation emitted during neutron irradiation, whereas in NAA radiation is measured after some time from irradiation (and this is the measurement of radioactivity of activation products). Application

The PGAA is a non-destructive method and is therefore readily used to study the composition of valuable and unique specimens such as works of art, archeological finds, etc. Its great advantage is a wide range of determinable elements and a large range of determinants (for many elements goes to single ppm). Typical measurements (depending on the sample mass and intensity of the neutron beam) take from a few minutes to several hours. Depending on the composition of the sample and the measurement time, the sample may show some radioactivity after measurement, however, as a rule, after a few days or weeks, the radioactivity drops to the background level. The neutron source is best used as a neutron source, but it is also possible to use neutron generators, combustion sources and others. In Europe, the PGAA has Munich Technical University and the Nuclear Center in Budapest.

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