A real smasher

After a major overhaul, the world’s only electron-proton collider got back to
work this week. The revamped HERA particle accelerator at the DESY research
centre in Hamburg will quadruple its “hit rate”, the rate at which particles
smash into each other. Experiments at the accelerator reveal quarks and gluons
milling around inside the proton and could soon shed light on whether quarks
really are elementary particles, as we believe today. “We are heading into
unexplored territory,” says Albrecht Wagner, DESY’s director.