Ariel Schwartzman

Two blindingly bright beams smash head-on. At the point of impact, a particle is born for an instant — the very one responsible for the mass of everything in the universe. That's the Higgs boson. Usually, it's produced by accelerating protons or electrons, but here the projectiles are particles of light themselves — photons.

A charged particle streaks through a silicon sensor, leaving behind a trail of free electrons. The time it takes for this charge to be collected at the electrode depends on how deep in the crystal it was born. A particle entering head-on carves identical paths through neighboring pixels: their signals arrive almost simultaneously.