91av

SURF’S up! Electrons riding a plasma wave can be accelerated to high energies, which may let us build small particle accelerators to smash them up and learn more about the tiniest objects in the universe.

The world’s largest accelerator, the Large Hadron Collider at the CERN particle physics laboratory near Geneva, Switzerland, smashes protons by whizzing them around a 27 kilometre ring, but that won’t work for electrons – they have to be accelerated in a straight line.

The Advanced Proton Driven Plasma Wakefield Acceleration Experiment, also at CERN, gets round this by shooting hundreds of billions of protons into a tube filled with rubidium atoms that have been stripped of electrons, forming a plasma. This results in waves in the plasma, and when electrons are injected into the tube, the waves accelerate them.

The container used is just 10 metres long, and the electrons at the end reached energies of 2 gigaelectronvolts (GeV) (Nature, ).

Electrons are fundamental particles, meaning we think they don’t break down into anything smaller. But we don’t know for sure. To test that would require smashing electrons at hundreds of GeV, which could be done using higher-energy protons.

This article appeared in print under the headline “A machine to split the electron”