S. Mohanty

Radioactive tritium decays, emitting an electron. Its energy is almost always the same, but sometimes, just a little less. This shortfall could mean that alongside the ordinary neutrino, another, hidden particle was born. The Standard Model describes three types of neutrinos, but scientists suspect there is a fourth — the sterile one.

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.