A half - life usually describes the decay of discrete entities, such as radioactive atoms. (myintimcity.com)
However, it has long been known that positrons are produced by the decay of radioactive atoms and by astrophysical phenomena, such as cosmic rays plunging into the atmosphere from outer space. (scientificamerican.com)
The idea that every particle has an identical — but so far undetectable — mirror partner was dreamed up to explain baffling asymmetries in the emission of electrons from radioactive atoms. (newscientist.com)