Noun
the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay
Source: WordNetAfter sitting for several years, the radioactivity reduces to a level where extraction of the long-lived isotopes, including technetium-99, becomes feasible. Source: Internet
A fallout shelter is designed to allow its occupants to minimize exposure to harmful fallout until radioactivity has decayed to a safer level. Source: Internet
Any interposing material would have interfered with the detection of radioactivity, since the beta particles emitted by decaying mainC are so weak that half are stopped by a 0.01 mm thickness of aluminium. Source: Internet
Arthur Holmes establishes radiometric dating Although Boltwood published his paper in a prominent geological journal, the geological community had little interest in radioactivity. Source: Internet
After 12 half-lives (43 days), radon radioactivity is at 1/2000 of its original level. Source: Internet
Antineutrinos are another kind of antiparticle created by natural radioactivity (β − decay). Source: Internet