Scientists have successfully developed a pocket-sized particle accelerator capable of emitting ultrashort electron beams using laser light at over 99.99% the speed of light. To achieve this result, the researchers had to slow down the light to match the speed of electrons using a specially designed metal structure covered with layers of silica thinner than a human hair. Scientists talked about their discovery in an article for Nature Photonics.

The new development simultaneously offers the ability to reshape and manipulate the clumps of particles on time scales of less than 10 femtoseconds (0.000 000 000 000 01 seconds, or the time it takes light to travel 1/100th of a millimeter). The new development will allow scientists to create stroboscopic photographs of the movement of atoms.

This successful demonstration paves the way for the development of high-energy, charged, high-quality terahertz (THz) accelerators that promise to be cheaper and more compact. Reducing the size and cost of accelerator technology will open it up to a much wider range of applications.

Particle accelerators are widely used in fundamental research in particle physics, material characterization, radiotherapy in hospitals where they are used to treat cancer patients, the production of radioisotopes for medical imaging, and security screening of goods. However, the core technology (radio frequency generators) underlying these machines was developed for radars during World War II.

Scientists’ unique solution is to use lasers to generate terahertz light pulses. Terahertz is the region of the electromagnetic spectrum between infrared (used in television remotes) and microwave (used in microwave ovens). The terahertz radiation generated by the laser exists in the millimeter-scale ideal wavelength mode, which simplifies the fabrication of the structure. And most importantly, it provides a half-cycle length that is well suited for accelerating entire high-charge electron bunches.