J. Hu

In 2016, the LHCb detector at the Large Hadron Collider recorded millions of proton-proton collisions. Among the debris of these collisions, neutral B mesons were born—particles that can spontaneously transform into their antiparticles and back.

Proton collisions at the Large Hadron Collider produce particles that live for less than a billionth of a second. One of them is the Bs meson, made of a strange quark and a bottom antiquark.

Deep in a Canadian mine, there's a barrel holding 3269 kilograms of liquid argon — a clear fluid that looks like very cold water. This barrel is the DEAP-3600 detector, and its job is to catch dark matter particles, which are thought to permeate the universe but barely interact with ordinary matter.

A pool of the purest water, into which tiny, almost invisible droplets occasionally fall. Each leaves a barely perceptible ripple, and capturing it requires years of patience. That is what the hunt for solar neutrinos looks like in the DEAP-3600 detector — a huge vat of liquid argon hidden deep underground.