Jian Tang

Deep inside the accelerator, neutrons are sped up and fly toward a target like a swarm of tiny tops. Each top has an axis of rotation: its spin. If all the tops are spun in the same direction, the beam is called polarized.

A huge pool of clear liquid is hidden deep underground. Inside, there is nothing but a pristine 'broth' that flashes with faint light when an invisible particle flies through. This is the JUNO detector—20,000 tons of liquid scintillator built to hunt for neutrinos. The main enemy of such a hunt is not darkness but its own noise.