Researchers, led by Lancaster and Manchester Universities, have had to slow down light to match the speed of the electrons using a specially designed metallic structure lined with ultrathin quartz layers.

They can now measure and manipulate particle bunches on time scales of less than 10 femtoseconds (1 femtosecond = 10-15 seconds). This will enable them to create strobe photographs of atomic motion.

This will lead to the development of high-energy, high-charge, high-quality THz-driven accelerators that are much cheaper and more compact. Cheap and powerful accelerator technology will have many new applications.

Particle accelerators are already used for particle physics, materials characterization, radiotherapy in hospitals (to treat cancer patients), radioisotope production for medical imaging, and security screening of cargo. The basic technology (radio-frequency oscillators) underpinning these machines, however, was developed for radar during the Second World War.