- For the first time, researchers develop a tiny silicon chip that can propel electrons in a distance smaller than the width of a human hair.
- The technology could accelerate particles fast enough to perform cutting-edge experiments in material science, chemistry, and biology.
Particle accelerators are giant machines that use electromagnetic fields to propel charged particles to extremely high speeds and energies. These high energy particles are then used to explore the fundamental structure of matter, space, and time
At present, more than 30,000 accelerators are in operation worldwide. They are used in various applications for scientific research, medicine, applied physics, and industrial processing.
These particle colliders are usually kilometers long circular tunnels. The most popular example is a 27-kilometer long Large Hadron Collider in Switzerland.
For the first time, a research team at the SLAC National Accelerator Laboratory has developed a tiny silicon chip that can propel electrons in a distance smaller than the width of a human hair. A conventional accelerator requires many feet to achieve the same sort of energy.
How Did They Do This?
Researchers cut a nanoscale channel from a silicon material and fixed it in a vacuum. They transmitted electrons through the cavity, and infrared light through the channel walls to boost the speed of electrons.
They were able to fire infrared light pulses through silicon, which hit electrons at just the right angle and right moment, accelerating them forward just a bit faster than before.
A part of silicon chip | The image is magnified 25,000 times | Gray structures focus infrared pulses (purple and yellow) on electrons flowing through a channel in the center | Credit: Neil Sapra
But conventional particle accelerators use microwaves, so why researchers used infrared light in this case? Well, silicon is transparent to infrared light as glass is to visible light. Therefore infrared pluses deliver more energy to electrons than microwaves.
This is just a prototype. The goal is to make it a more accessible research tool by miniaturizing the accelerator technology.
Just as computing evolved from the mainframe to the desktop PC, particle accelerators could be compressed into a small silicon chip. The technology could accelerate particles fast enough to perform cutting-edge experiments in material science, chemistry, and biology.
In this study, researchers have explained how their approach could lead to new cancer radiation therapies. Existing large X-ray machines deliver electron beam radiation that is hard to focus on tumors. Thus patients are required to wear shields to minimize collateral damage. The new technology could deliver a beam of radiation directly to a tumor, without affecting healthy tissues.
The team aims to accelerate electrons to 1 million electron volts (1 MeV), or 94% of the speed of light so that these particles can be used for conducting scientific research.
The silicon chip developed in this study represents only one stage of acceleration. To achieve 1 MeV, the electrons would have to pass through approximately one thousand stages.
Since the chip is designed and fabricated using efficient techniques, it should be reasonably straightforward to increase its capabilities. The team is currently working to integrate a thousand acceleration stages into an inch of chip space.
It would be a great milestone but those chips would still be far less powerful than conventional particle accelerators, which can produce 30,000 times higher energy levels than 1 MeV.
However, researchers believe that, just as electronic transistors ultimately replaced vacuum tubes, infrared-based equipment will one day deliver the same performance as microwave-based accelerators.