N. J. C. Spooner

In a dark room, a hunter waits for a barely audible rustle. Similarly, physicists have spent years listening for signals from dark matter particles — the invisible substance that holds galaxies together but doesn't emit light. The new detector makes this 'hearing' a hundred thousand times sharper. Inside the device is SF₆ gas (the same stuff that quenches sparks in electrical grids).

Deep in a cave beneath the Italian Apennines, a tank of gas sits in the dark. Inside, charged particles fly through, leaving faint flashes of light in their wake. These flashes are like the wake of a boat on dark water: they reveal where the particle went and how fast.