From 100 km down to just 2.5 cm … the future of particle accelerators

Heard of the LHC?

Properly called the Large Hadron Collider, it’s a massive particle accelerator, ie. it’s a 27km ring with a lot of magnets that’s buried underground between France and Switzerland. It’s pretty exciting because it can speed particles up to just about light-speed (0.999997828 of light-speed for those who are interested). They get two beams of these ultra-speedy particles and set them off into the ring. And here’s where it gets exciting. They let the two particles beams in going different directions.

Like two cars going opposite directions on a one-lane racetrack, these particles are going to collide …. and release all that speed into energy. Then, as scientists are want to do, they observe what happens.

And on July 4th 2012, 4 years after beginning experiments, the scientists reported that they’d discovered the Higgs Boson, a fundamental particle as part of the Standard Model (not going to go into heaps of detail here, but its thought that its existence provides mass to all other particles).

The discovery of the Higgs Boson was the primary of the entire LHC project (not to say that they’re not still working out more science and fine-tuning all the details) ever since its earliest days of planning back in 1980s when they were still building its precursor- the Large Electron-Positron collider. Nothing like advance planning!

The LHC and the proposed FCC. Image sourced from CERN

And today, while the LHC is still schedule and planned to run up to at least 2035, scientists are well on the way to planning the next big exciting thing, aptly named the Future Circular Collider. It would be a staggering 100km in circumference and 10 times more powerful than the LHC. It’d cost over $15 billion AUD, but they are thinking about reusing some components- having the area from the LHC overlap with the proposed FCC so certain systems can simply be reused. If they start building now, they could probably have it up and running when the LHC reaches the end of its operational lifespan.

With this brand new collider, they’d like to investigate how Higgs particles interact with each other, as the LHC isn’t powerful enough to generate multiple of these at once (remember, it took 4 years for it to even confirm the existence of the Higgs Boson). But its price tag is more than nasty, so we’ll see where that one ends up!



Going cheaper and tinier

However, modern technology is also working the opposite way. While the determined particle physicists are building bigger and better, there’s another group of researchers who are experts in particle accelerators and nanotechnology.

Yup. They’re making these things as little as possible.

Because particle accelerators can be very useful for far more than colliding protons to observe fundamental particles. They could be a means of extremely precise radiation therapy for cancer (avoiding damage to non-tumour tissues), create images that would look like incredibly detailed x-rays, probe molecule structures … the list continues. But until quite recently, the smallest ones have been taking up rooms. Creating a 2-metre one (miniature linear accelerator, the mini-Linac) was exciting news for medicine.


Chip-sized and made of silicon!

So then, what about one that fits on a computer chip? While it’s definitely still in infant stages, the group of ACHIP (Accelerator on a Chip International Program) researchers have announced the results of their first silicon-chip accelerator. While the LHC uses massive vacuum tunnels, the chip’s vacuum tunnels are 30 micrometres long and entirely sealed. The electrons are powered by infra-red laser pulses (up to 100,000 per second) instead of the LHC’s superconducting magnets. The group estimates that using 1000 of them together will provide the necessary power, and bring the whole apparatus to a final size of only 2.5cm!

They’re hoping to bring the technology to the point of accelerating these electrons to 94% of the speed of light (0.94 compared to 0.999997828 on the LHC). It’s a big difference, but still plenty enough for application in cancer treatment and for use by scientists when they can’t justify or afford a research trip out to a large accelerator.

What’s more, they think they have a chance of getting there by the end of 2020. So stay alert for more interesting developments to come!

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