The XENON Collaboration research announced that they have observed the radioactive decay of xenon-124, which has a half-life of 1.8 X 10²² years: a process that takes more than one trillion times longer than the age of the universe User Mass1m01973, in the Reddit Science subreddit, 25 Apr 2019
Observation of two-neutrino double electron capture in 124 Xe with XENON1T User dukwon, in the Physics subreddit, 24 Apr 2019