Stanford Scientists Build Chip-Size Particle Accelerator

(CN) – Scientists have created a prototype particle accelerator so small it can fit on a single chip, a drastic size decrease and potentially tremendous step forward for the technology.

This image, magnified 25,000 times, shows a section of a prototype accelerator-on-a-chip. The segment shown here is one-tenth the width of a human hair. The oddly shaped gray structures are nanometer-sized features carved in to silicon that focus bursts of infrared laser light, shown in yellow and purple, on a flow of electrons through the center channel. As the electrons travel from left to right, the light focused in the channel is carefully synchronized with passing particles to move them forward at greater and greater velocities. By packing 1,000 of these acceleration channels onto an inch-sized chip, Stanford researchers hope to create an electron beam that moves at 94% of the speed of light and to use this energized particle flow for research and medical applications. (Image courtesy of Neil Sapra)

A study published Thursday in the journal Science details how a team of researchers at Stanford University and the SLAC National Accelerator Laboratory created a particle accelerator, a machine used to propel particles like electrons and protons at extremely high speeds in order to create particle beams, that is small enough to function on a small chip made of silicon.

Particle accelerators can be huge – the one on a hillside above Stanford University stretches almost two miles – so one built to such a small scale represents a huge advancement in particle accelerator technology given its varied uses.

“Particle accelerators represent an indispensable tool in science and industry. However, the size and cost of conventional radio-frequency accelerators limit the utility and reach of this technology,” the study states.

Neil Sapra, first author of the study, said the breakthrough is so significant because despite their value, particle accelerators have been large and cumbersome for years – even those labeled as compact.

“Particle accelerators are commonly used for medical (cancer treatments, imaging techniques) and industrial (ion implantation, sterilization, imaging) applications, but ‘compact’ accelerators for these applications still take up entire rooms or the backs of semi-trucks. Part of the reason for this is that they are based on radio-frequency waves, which have a long wavelength,” Sapra said in an email.

Sapra said his team’s research focused on a different type of accelerator known as a dielectric laser accelerator, or DLA, which uses a much smaller wavelength. The smaller wavelength allows the size of the device to be so significantly reduced, Sapra said.

“Due to this much smaller operating wavelength, DLAs have the potential to be more compact by an order of 10,000,” Sapra said.

Researchers note one small reality to consider when understanding this kind of accelerator is the kind of particle velocities the device is capable of. The structure and size of the chip-sized particle accelerator means it is only capable of a fraction of the velocity that its large-scale counterparts can produce.

Its lesser velocities, researchers say, do not detract from its potential given the crucial importance particle accelerators continue to play in the ever-advancing fields of medical and industrial technologies. A device this small and accessible, researchers hope, could open new doors in those fields that were previously thought to be unexplorable.

Sapra said the breakthrough creates a path to make this critical technology more readily available and in turn, more affordable.

“In this work we showed on-chip acceleration of a short distance, but the inherit scalability of integrated photonics provides us now with a clear road-map towards more stages of acceleration,” Sapra said. “The ultimate goal of our Accelerator on a Chip International Program (ACHIP) is to achieve an accelerator capable of producing 1 MeV energy beams which can be a truly compact (imagine shoe-box size or even smaller) particle accelerator for medical, industrial, and scientific applications that can be widely and cheaply available.”

Researchers hope the advancements made through this prototype’s construction will help to not only advance the field of particle accelerators and encourage continued breakthroughs, but also provide meaningful and positive changes to the fields that depend on this technology.

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