L. Pagani

Deep inside an underground laboratory, a room-sized detector waits for an event that might happen once in a hundred million billion years. That event is neutrinoless double beta decay — a process that would break one of physics' fundamental laws. To catch it, you need perfect silence: not a single stray radioactive atom in the detector's materials.

A bullet that doesn't just pierce one target but leaves marks in several layers of armor. That's roughly how superheavy dark matter behaves, and it's what the DarkSide-50 detector was built to catch for the first time. The usual suspects for dark matter (weakly interacting massive particles, or WIMPs) pass through matter almost unnoticed, occasionally bumping into a nucleus.