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$13.5M Moore Grant to Develop Working ‘Accelerator on a Chip’ Prototype

$13.5M Moore Grant to Develop Working ‘Accelerator on a Chip’ Prototype

The Goal: Build a Shoebox-sized Particle Accelerator in 5 Years
November 19, 2015

Menlo Park, Calif. — The Gordon and Betty Moore Foundation has awarded $13.5 million to Stanford University for an international effort, including key contributions from the Department of Energy’s SLAC National Accelerator Laboratory, to build a working particle accelerator the size of a shoebox based on an innovative technology known as “accelerator on a chip.”

This novel technique, which uses laser light to propel electrons through a series of artfully crafted chips, has the potential to revolutionize science, medicine and other fields by dramatically shrinking the size and cost of particle accelerators.

“Can we do for particle accelerators what the microchip industry did for computers?” said SLAC physicist Joel England, an investigator with the 5-year project. “Making them much smaller and cheaper would democratize accelerators, potentially making them available to millions of  people. We can’t even imagine the creative applications they would find for this technology.”

Robert L. Byer, a Stanford professor of applied physics and co-principal investigator for the project who has been working on the idea for 40 years, said, “Based on our proposed revolutionary design, this prototype could set the stage for a new generation of ‘tabletop’ accelerators, with unanticipated discoveries in biology and materials science and potential applications in security scanning, medical therapy and X-ray imaging.”

An international team of researchers has begun a 5-year effort to build a working particle accelerator the size of a shoebox based on an innovative technology known as “accelerator on a chip.”

The Chip that Launched an International Quest

The international effort to make a working prototype of the little accelerator was inspired by experiments led by scientists at SLAC and Stanford and, independently, at Friedrich-Alexander University Erlangen-Nuremberg (FAU) in Germany. Both teams demonstrated the potential for accelerating particles with lasers in papers published on the same day in 2013.

In the SLAC/Stanford experiments, published in Nature, electrons were first accelerated to nearly light speed in a SLAC accelerator test facility.  At this point they were going about as fast as they can go, and any additional acceleration would boost their energy, not their speed.

The speeding electrons then entered a chip made of silica glass and traveled through a microscopic tunnel that had tiny ridges carved into its walls. Laser light shining on the chip interacted with those ridges and produced an electrical field that boosted the energy of the passing electrons.

In the experiments, the chip achieved an acceleration gradient, or energy boost over a given distance, roughly 10 times higher than the SLAC linear accelerator can provide. At full potential, this means the 2-mile-long linac could be replaced with a series of accelerator chips 100 meters long ­– roughly the length of a football field. 

In a parallel approach, experiments led by Peter Hommelhoff of FAU and published in Physical Review Letters demonstrated that a laser could also be used to accelerate lower-energy electrons that had not first been boosted to nearly light speed. Both results taken together open the door to a compact particle accelerator.

These microscopic images show some of the accelerator-on-a-chip designs being explored by the international collaboration. In each case, laser light shining on the chip boosts the energy of electrons traveling through it. (Left and middle images: Andrew Ceballos, Stanford University. Right image: Chunghun Lee, SLAC)

A Tough, High-payoff Challenge

For the past 75 years, particle accelerators have been an essential tool for physics, chemistry, biology and medicine, leading to multiple Nobel prize-winning discoveries. They are used to collide particles at high energies for studies of fundamental physics, and also to generate intense X-ray beams for a wide range of experiments in materials, biology, chemistry and other fields. But without new technology to reduce the cost and size of high-energy accelerators, progress in particle physics and structural biology could stall.

The challenges of building the prototype accelerator are substantial, the scientists said. Demonstrating that a single chip works was an important step; now they must work out the optimal chip design and the best way to generate and steer electrons, distribute laser power among multiple chips and make electron beams that are 1,000 times smaller in diameter to go through the microscopic chip tunnels, among a host of other technical details.

“The chip is the most crucial ingredient, but a working accelerator is way more than just this component,” said Hommelhoff, a professor of physics and co-principal investigator of the project. “We know what the main challenges will be and we don’t know how to solve them yet. But as scientists we thrive on this type of challenge. It requires a very diverse set of expertise, and we have brought a great crowd of people together to tackle it.”

The Stanford-led collaboration includes world-renowned experts in accelerator physics, laser physics, nanophotonics and nanofabrication. SLAC and two other national laboratories ­– Deutsches Elektronen-Synchrotron (DESY) in Germany and Paul Scherrer Institute in Switzerland – will contribute expertise and make their facilities available for experiments. In addition to FAU, five other universities and one industry partner are involved in the effort:  University of California, Los Angeles, Purdue University, University of Hamburg, the Swiss Federal Institute of Technology in Lausanne (EPFL), Technical University of Darmstadt and Tech-X Corporation.

“The accelerator-on-a-chip project has terrific scientists pursuing a great idea. We’ll know they’ve succeeded when they advance from the proof of concept to a working prototype,” said Robert Kirshner, chief program officer of science at the Gordon and Betty Moore Foundation. “This research is risky, but the Moore Foundation is not afraid of risk when a novel approach holds the potential for a big advance in science. Making things small to produce immense returns is what Gordon Moore did for microelectronics.”


Press Office Contact: Andrew Gordon, agordon@slac.stanford.edu, (650) 926-2282


SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit www.slac.stanford.edu.

Gordon and Betty Moore Foundation fosters path-breaking scientific discovery, environmental conservation, patient care improvements and preservation of the special character of the Bay Area. Visit www.moore.org or follow @MooreFound.

SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

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Three accelerator chips on a finger
Three “accelerators on a chip” made of silicon are mounted on a clear base. A shoebox-sized particle accelerator being developed under a $13.5 million Moore Foundation grant would use a series of these “accelerators on a chip” to boost the energy of electrons. (SLAC National Accelerator Laboratory)
A diagram shows one possible configuration for the shoebox-sized particle accelerator prototype. Designing the accelerating chips is just one of the challenges facing the project. The Stanford-led team will have to figure out the best way to distribute laser power among the chips, generate and steer the electrons, shrink the diameter of the electron beam 1,000-fold and a host of other technical details. SLAC and two other national labs will contribute expertise and make their facilities available for this effort. (SLAC National Accelerator Laboratory)
Each "accelerator on a chip" is nanostructured using advanced fabrication techniques to provide the desired acceleration effect. (SLAC National Accelerator Laboratory)
Making accelerators much smaller would provide benefits to research, medicine and other applications. (SLAC National Accelerator Laboratory)
The accelerator-on-a-chip researchers are testing a variety of materials and structures to find the optimal components for a prototype accelerator. (SLAC National Accelerator Laboratory)
Much like the computer chips that made Gordon Moore famous, the accelerator on a chip could dramatically shrink the size of accelerator technology to benefit society. (SLAC National Accelerator Laboratory)
Photo of research team at project kickoff meeting.
Members of the international scientific collaboration to build a working prototype of a particle accelerator based on “accelerator on a chip” technology gathered at the Moore Foundation in October for a kick-off meeting to discuss the endeavor. (SLAC National Accelerator Laboratory)