Fine Structure

Neutrinoless Double Beta Decay at EXO

David Harris has two interesting articles from symmetry breaking this weekend. The first is an investigation of how to measure the inner structure of a proton (which is harder than simply saying "up, up, down" apparently).

The second one, which I find much more interesting, is about neutrinoless double beta decay in an isotope of xenon. Double beta decay is a process in which a single decay results in two neutrinos being emitted and is the rarest kind of radioactive decay. The key to the Enriched Xenon Observatory detector is the neutrinoless part - it's theoretically possible for double beta decay to occur and produce only two electrons but in that case, neutrinos would have to be their own antiparticle. The EXO will eventually provide two ways to see if neutrinoless beta decay has occurred, by the detection of the emitted electrons and by detection of a single resulting barium atom in more than 1028 xenon atoms. ]