neutroniaktivointianalyysia

Neutroniaktivaatioanalyysi, often abbreviated NAA, is a nuclear technique used for determining the elemental composition of a sample. It involves bombarding a sample with neutrons, which causes some of the atoms in the sample to become radioactive isotopes. These isotopes then emit characteristic gamma rays as they decay. By measuring the energy and intensity of these gamma rays, scientists can identify and quantify the elements present in the sample.

The process begins by exposing the sample to a neutron flux, typically from a nuclear reactor or a neutron generator. The neutrons are absorbed by the nuclei of certain elements, transforming them into unstable, radioactive isotopes. These activated isotopes have unique decay properties, including specific half-lives and gamma-ray energies. After irradiation, the sample is placed in a detector, usually a high-purity germanium (HPGe) detector, which is sensitive to gamma radiation. The detector records the emitted gamma rays, creating a spectrum that shows peaks at energies characteristic of the activated isotopes. The position of these peaks identifies the elements, while the height of the peaks, relative to a known standard, indicates their concentration.

NAA is a highly sensitive technique, capable of detecting trace elements down to parts per billion or even parts per trillion levels for some elements. It is a non-destructive method, meaning the sample can often be recovered and used for other analyses after the NAA measurement, provided the radioactivity is not too high. NAA finds applications in a wide range of fields, including geology, archaeology, environmental monitoring, forensics, and materials science, where precise elemental analysis is crucial.