polonium-210

Polonium-210 (210Po, Po-210, historically radium F) is an isotope of polonium. It undergoes alpha decay to stable 206Pb with a half-life of 138.376 days (about months), the longest half-life of all naturally occurring polonium isotopes (210–218Po). First identified in 1898, and also marking the discovery of the element polonium, 210Po is generated in the decay chain of uranium-238 and radium-226. 210Po is a prominent contaminant in the environment, mostly affecting seafood and tobacco. Its extreme toxicity is attributed to intense radioactivity, mostly due to alpha particles, which easily cause radiation damage, including cancer in surrounding tissue. The specific activity of is 166 TBq/g, i.e., . At the same time, 210Po is not readily detected by common radiation detectors, because its gamma rays have a very low energy. Therefore, can be considered as a quasi-pure alpha emitter.

==History== thumb|left|250px|The decay chain of uranium-238, known as the uranium series or radium series, of which polonium-210 is a member thumb|left|250px|Schematic of the final steps of the s-process. The red path represents the sequence of neutron captures; blue and cyan arrows represent [[beta decay, and the green arrow represents the alpha decay of 210Po. It is the short half-lives of 210Bi and 210Po that prevent the formation of heavier elements, instead resulting in a cycle of four neutron captures, two beta decays, and an alpha decay.]]