Particle accelerators to the rescue

The LHC is probably the world’s most famous particle accelerator, but there are over 20,000 more scattered across the globe. And they aren’t all set on probing the secrets of the universe or finding the Higgs boson.

In fact, they can accomplish a whole lot of other tasks that might surprise you. We spoke to expert Dr Suzie Sheehy about what particle accelerators can do for us, from treating cancer to revealing the secrets of tasty chocolate.

1. Particle therapy

All cancer treatments face the same challenge: destroying cancerous tumours whilst causing as little harm as possible to the rest of the patient’s body.

Many cancers are treated with radiotherapy, which involves blasting the tumour with x-ray radiation. This is bad news for the tumour, but also for nearby organs and tissue. ‘When you send an x-ray into tissue it will destroy everything in its path,’ explains Sheehy.

Exposing healthy cells to x-rays causes a range of side-effects, from skin reactions to digestive problems. Paradoxically, it also increases the patient’s chances of developing cancer again in later life.

One alternative is to bombard the tumour with charged particles using (you guessed it) a particle accelerator. Unlike x-rays, charged particles deposit all their cell-busting energy at a pre-defined depth (known as the Bragg peak), meaning the tumour can be targeted much more precisely.

‘It’s a better way of treating cancer because you’re saving more healthy tissue but you’re putting the energy for killing cells exactly where you need it,’ says Sheehy.

Charged particle therapy is already in use in 22 centres around the world and has treated over 70,000 patients. The particle accelerators it requires are very expensive, but ongoing research will hopefully shrink both their size (they currently fill a large room) and their price tag.

2. Nuclear power lite

Nuclear power is a divisive issue. Some see this carbon-free energy source as our best chance of slowing climate change. But nuclear waste, arms proliferation and the risk of tragic accidents leave a bad taste in many people’s mouths.

Accelerator Driven Sub-critical Reactors (or ADSR for short) however hold the potential for worry-free nuclear power. ‘ADSR solves a lot of the problems that governments and societies have with current nuclear technology,’ comments Sheehy.

Instead of uranium, an ADSR reactor is fuelled by thorium. This metal behaves similarly to uranium in some ways, but with a few fundamental differences.

Inside a traditional nuclear reactor, each fission reaction splits a uranium atom, releasing two neutrons, which go on to spark two more reactions, releasing four neutrons, which trigger four more reactions, and so on. Keep repeating this process, and hey presto, it’s a nuclear chain reaction.

Chain reactions unleash a huge amount of energy, which is great for producing power, but if they ever get out of control the consequences can be truly disastrous, as accidents like Chernobyl go to show.

With thorium, the fission reactions produced are not self-sustaining but instead need to be driven by a high-powered beam of neutrons. If there is an incident, the reactions can therefore be stopped at the flick of a switch (although the reactor still needs to be cooled down to prevent damage). 'This makes it much safer than a conventional nuclear reactor', says Sheehy.

The benefits don’t end there. Compared to conventional nuclear power, ADSR would produce a smaller quantity of less radioactive waste and could even be used to process existing nuclear waste into less dangerous forms.

Finally, there is no danger of ADSR nuclear power contributing to the spread of nuclear arms. Waste from existing nuclear plants can be re-processed to build  weapons, meaning that nuclear power and the proliferation of nuclear arms are inseparable issues. Thorium on the other hand is no use to weapon makers.

There is of course a flipside to this long list of advantages. ‘There’s a lot of research to be done before ADSR can come to fruition,’ explains Sheehy. ‘At every step in the process, it’s new technology.’

Sheehy is currently working on an accelerator that she hopes will produce the high-intensity particle beams needed to drive ADSR. ‘I find it motivating to have this application that will hopefully help people,’ she says.

3. Better wine and chocolate

Aside from tackling the world’s energy crisis and curing cancer, particle accelerators have helped with some smaller scale (but equally important) endeavours: making yummier chocolate and checking the authenticity of vintage wines.

This type of research is done at synchrotron radiation sources (such as Diamond Light Source or ESRF) which use an intense beam of x-ray light to probe the structure of samples. At these research facilities, anyone can apply for some beam time to carry out their own research project.

In 1998, chocolate giant Cadbury’s used synchrotron radiation to take a closer look at their chocolate’s structure. It turns out that cocoa butter can crystallise in six different ways, and that one of these produces a much smoother chocolate.

So next time you tuck into a bar of dairy milk, you can thank particle accelerators for its melt in the mouth texture.

If fine wines are your thing, synchrotron radiation can help you to make sure the fancy bottle you’ve bought is the real deal. ‘You can tell if the wine is authentic by testing the structure of the glass bottle,’ explains Sheehy.

The exact chemical composition of glass bottles has changed over time and also varies depending on it where the bottle was made. By analysing the glass you can therefore pinpoint where and when a given bottle of wine originates from. ‘The dating of antique bottles of wine is definitely my favourite application of particle accelerators!’ laughs Sheehy.


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