Scattered around our world are a variety of underground detectors that are protected from the random noise of space and are tuned in to look for the specific flashes of light that can occur when particles like neutrinos collide with specific liquids. One particular detector, the XENON1T in Italy is filled with ultra-pure liquid xenon. Designed to search for certain theoretical kinds of dark matter, it has so far found none of the particles it hoped for, but it has found a weird background of particle interactions that weren’t expected. 

While there is a chance that what they are seeing is the noise created by a few stray tritium atoms in their detector, they could also be observing some kind of a previously unobserved particle, like an axion from the Sun, or they could be seeing an effect caused by neutrinos having a higher magnetic moment then currently expected. Since it would only require a few tritium atoms for every 10^25 xenon atoms to cause this effect, I’m not going to suggest it’s time to get excited about potential new physics. It’s still cool though to see discussed the possibility that axions are being detected as noise in a dark matter detector while dark matter isn’t detected. We’re pretty sure this result will turn out to be absolutely not exciting, but just in case it is, we’ll be keeping an eye on how this story evolves.

More Information

Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) press release 

“Observation of Excess Events in the XENON1T Dark Matter Experiment,” XENON Collaboration, 2020 June 17 (Preprint on arxiv.org)