Researchers Measure Atom With Half-Life of 18 Sextillion Years

A detector designed to hunt for dark matter has succeeded in detecting one of the rarest particle interactions in the universe. 'According to a new study published today in the journal Nature, the team of more than 100 researchers measured, for the first time ever, the decay of a xenon-124 atom into a tellurium 124 atom through an extremely rare process called two-neutrino double electron capture,' reports Live Science. 'This type of radioactive decay occurs when an atom's nucleus absorbs two electrons from its outer electron shell simultaneously, thereby releasing a double dose of the ghostly particles called neutrinos.' From the report: By measuring this unique decay in a lab for the first time, the researchers were able to prove precisely how rare the reaction is and how long it takes xenon-124 to decay. The half-life of xenon-124 -- that is, the average time required for a group of xenon-124 atoms to diminish by half -- is about 18 sextillion years (1.8 x 10^22 years), roughly 1 trillion times the current age of the universe. This marks the single longest half-life ever directly measured in a lab. Only one nuclear-decay process in the universe has a longer half-life: the decay of tellurium-128, which has a half-life more than 100 times longer than that of xenon-124. But this vanishingly rare event has only been calculated on paper.

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