Scientists have made a particle accelerator so small, it’s just half the diameter of a human hair. Their goal was to make an accelerator that could fit on an integrated chip, and they did it by allowing a computer to design the chip. The researchers say they’d never have envisioned the design with only their human brains.
They use an existing technology called dielectric laser acceleration but have designed a new form of acceleration using a computer algorithm. Having a nano-sized accelerator sounds like wild research for its own sake, but a scalable, modular, and easily manufacturable accelerator on a chip is actually a big goal within several different fields that want to apply it to healthcare and other markets for imaging. The Stanford team has already improved on the microwave-powered SLAC linear accelerator and is hopeful it can tune the accelerator to do much better than that.
Lead author Neil Sapra told Vice that the chip compatibility is the most important thing about this piece of research. To condense a complex device into a size that could be installed on a chip, the team had to figure out how to cram a huge amount of directed light into a nanoscale area. The team’s computer studied the desired outcome and designed an engraved surface that corralled bouncing light in the most efficient and optimized way.
Sapra says the next big step in his team’s research is to make a micro accelerator that can keep firing the microbursts of acceleration—for now, the hairs width one can only do one burst, and they need to do 999 more bursts to get the particles up to the range of speed known as MeV (megaelectronvolt). This will accelerate each electron by 1,000,000 volts in total. The team’s target devices, like medical X-rays and radiation therapy, operate in this range and stand to benefit a great deal from much smaller, much cheaper accelerators.
How do scientists measure output on such an astonishingly tiny scale? “By comparing the measured electron energy spectra with particle-tracking simulations, we infer a maximum energy gain of 0.915 kilo–electron volts over 30 micrometers, corresponding to an acceleration gradient of 30.5 mega–electron volts per meter,” the team wrote in its new paper.
This article was written by Caroline Delbert and published by Popular Mechanics on 1/6/2020