nøytronaktiveringsanalyse

Neutron activation analysis (NAA) is a nuclear technique used for determining the elemental composition of materials. It works by irradiating a sample with neutrons, typically from a nuclear reactor or a neutron generator. When a stable isotope in the sample captures a neutron, it becomes an unstable radioactive isotope. This newly formed radioisotope then decays by emitting gamma rays. The energy and intensity of these gamma rays are unique to each specific radioisotope, allowing for the identification and quantification of the elements present in the original sample.

The process involves several steps. First, the sample is exposed to a neutron flux. The duration of irradiation depends on the half-lives of the isotopes of interest and the desired sensitivity. After irradiation, the sample is placed in a detector, usually a high-purity germanium (HPGe) detector, which is capable of measuring the characteristic gamma rays. The emitted gamma rays are recorded, and their energies are analyzed to identify the elements, while their intensities are measured to determine their concentrations.

NAA is a highly sensitive technique, capable of detecting trace and ultra-trace amounts of many elements. It is a non-destructive technique for many sample types, meaning the sample can be analyzed again or used for other purposes after the analysis. Its applications span a wide range of fields, including geology, archaeology, environmental monitoring, forensics, materials science, and medicine. For instance, it is used to analyze the elemental composition of rocks, pottery, forensic evidence, and biological tissues. The accuracy and reliability of NAA make it a valuable tool for scientific research and industrial quality control.