Scientists create 'accelerator on a chip' - EE Times India

A team of scientists from the U.S. Department of Energy's SLAC National Accelerator Laboratory and Stanford University has used a laser to accelerate electrons in a nanostructured glass chip smaller than a grain of rice, at a rate 10 times higher than conventional technology.

This development can dramatically reduce the size of particle accelerators to be used in medicine.

The new "accelerator on a chip" could match the accelerating power of SLAC's 2-mile-long linear accelerator in just 100 feet, and deliver a million more electron pulses per second, claimed the researchers.

"We still have a number of challenges before this technology becomes practical for real-world use, but eventually it would substantially reduce the size and cost of future high-energy particle colliders for exploring the world of fundamental particles and forces," said Joel England, the SLAC physicist who led the experiments.

"It could also help enable compact accelerators and X-ray devices for security scanning, medical therapy and imaging, and research in biology and materials science."

Because it employs commercial lasers and low-cost, mass-production techniques, the researchers believe it will set the stage for new generations of "tabletop" accelerators.

Particles are generally accelerated in two stages. First they are boosted to nearly the speed of light. Then any additional acceleration increases their energy, but not their speed; this is the challenging part.

In the accelerator-on-a-chip experiments, electrons are first accelerated to near light-speed in a conventional accelerator. Then they are focused into a tiny, halfµm-high channel within a fused silica glass chip just half a millimeter long. The channel had been patterned with precisely spaced nanoscale ridges. Infrared laser light shining on the pattern generates electrical fields that interact with the electrons in the channel to boost their energy.

Turning the accelerator on a chip into a full-fledged tabletop accelerator will require a more compact way to get the electrons up to speed before they enter the device.

Applications for these new particle accelerators would go well beyond particle physics research. The laser accelerators could drive compact X-ray free-electron lasers, comparable to SLAC's Linac Coherent Light Source, that are all-purpose tools for a wide range of research.

Another possible application is small, portable X-ray sources to improve medical care for people injured in combat, as well as provide more affordable medical imaging for hospitals and laboratories.

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