radon220

Radon-220, also known as thoron, is a radioactive isotope of the noble gas radon. It has a mass number of 220 and is part of the thorium-232 decay chain. Thoron is produced in the natural environment as thorium-232 decays through a series of short-lived radionuclides, ultimately yielding radon-220, which then decays further to polonium-216.

The principal characteristic of radon-220 is its short half-life of about 55.6 seconds. It decays by alpha emission to polonium-216. Because of this brief half-life, thoron has limited mobility in air and tends to exist only near its source, in contrast to radon-222, which can accumulate and diffuse over longer distances.

Occurrence and sources vary with geological and material composition. Radon-220 is found in trace amounts in soils and rocks containing thorium. In indoor environments, thoron can contribute to radiation exposure when building materials are rich in thorium and are in close contact with occupied spaces. However, its rapid decay means its concentration diminishes quickly with distance from the source.

Health considerations focus on the alpha radiation emitted by radon-220 and its progeny. Inhalation can pose a radiological health risk, but the short half-life reduces overall exposure potential compared with longer-lived radon isotopes. Measurement and risk assessment for thoron require detectors capable of capturing its short-lived presence, often used in conjunction with radon-222 monitoring.

See also: Radon, Thorium-232 decay series, Thoron (common name for radon-220), Radiation protection.

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