Could tiny chips no bigger than grains of rice do the job of a huge particle accelerator? At full potential, a series of these “accelerators on a chip” could boost electrons to the same high energies achieved in SLAC National Accelerator Laboratory’s 2-mile linear accelerator in a distance of just 100 feet. This could make accelerators a lot smaller and more affordable.
The Gordon and Betty Moore Foundation has awarded $13.5 million to an international collaboration led by Stanford University, to develop a working prototype of such an accelerator over the next five years. SLAC and two other national labs provide key in-kind contributions in support of this expansive university effort.
Here’s how “accelerator on a chip” works: Electrons enter the chip and travel through a microscopic tunnel that has tiny ridges carved into its walls. When scientists shine an infrared laser on the chip, the light interacts with those ridges and produces an electrical field that boosts the energy of the passing electrons. In experiments at SLAC, the chip achieved an acceleration gradient, or energy boost over a given distance, roughly 10 times higher than the SLAC linear accelerator can provide.
There’s a lot of work to do to make this technology practical for real-world use. For instance, creating a full-fledged tabletop accelerator will require a more compact way to get electrons up to speed before they enter the chip; the Moore Foundation’s funding will help scientists work on that, and ideally create a prototype the size of a shoebox.
On the plus side, the accelerator on a chip uses commercial lasers and can be manufactured with low-cost, mass-production techniques.
Scientists think a series of these tiny chips could greatly reduce the size and cost of particle accelerators for a variety of applications. For example, the technology could help make compact low-cost accelerators and X-ray devices for security scanning, medicine, biology and materials science. Small, portable X-ray sources could improve medical care for people injured in combat and reduce the cost of medical imaging in hospitals.
Editor's Note: SLAC is one of the Department of Energy's 17 National Laboratories.