Argon38

Argon-38 is a radioactive isotope of the noble gas argon. It has an atomic number of 18 and a mass number of 38 (symbol 38Ar). In natural argon, the predominant isotope is Argon-40, with trace Argon-36 and Argon-38, but 38Ar is not present in any appreciable amount due to its instability. It is primarily produced in laboratory nuclear reactions or through high-energy cosmic-ray spallation.

As a proton-rich nuclide (its neutron-to-proton ratio is lower than that of the stable isotopes), Argon-38 decays to chlorine-38. The decay is typically via beta-plus emission or electron capture, transforming a proton into a neutron while reducing the atomic number by one. Its half-life is very short, on a timescale that is generally considered to be milliseconds to seconds, which means it cannot be detected long in ordinary, ambient conditions.

Production and study of 38Ar occur in experimental nuclear physics settings. It can be generated through targeted nuclear reactions, such as irradiation of suitable target nuclei with accelerated particles, or through fragmentation processes in high-energy collisions. Because of its brief existence, Argon-38 is mainly of interest for investigations into the properties of light, proton-rich nuclides and for testing nuclear models and decay schemes rather than for practical applications.

See also: Argon isotopes, Argon-39 dating, nuclear stability.