How do synchrotrons work?

Synchrotrons are powerful machines that tell us about the fabric of the world around us but how do they actually work?
04 August 2014

Interview with 

Ed Rial, Diamond Light Source


The Diamond Light Source is a synchrotron, which is a form of Diamond Light Sourceparticle accelerator. It uses a powerful magnetic field to propel a stream of negative particles - called electrons - in a long circular path at close to the speed of light. As the electrons follow the curve of the half-a-kilometre long path they give off beams of x-rays 10,000 times brighter than the Sun, which scientists are able to tap-off and use to study the structures of crystals or jet engine parts and even to read ancient manuscripts! Graihagh Jackson went to Diamond, in Oxfordshire's countryside, to see how it works...

Ed -   My name is Ed Rial.  I work here as an Insertion Device Physicist.  So, I make some of the special magnets here that make Diamond especially bright.  Diamond is a series of particle accelerator that accelerate electrons up to pretty much the speed of light and basically, used light like a diamond microscope to really see the very small details of matter.

Graihagh -   How is Diamond different from CERN?

Ed -   So, CERN is a giant machine in the Swiss Alps and they accelerate particles called protons.  They smash those together at massive energies to really look at fundamental sequence of matter and what was going on in the early stage of the universe. 

At Diamond, we accelerate electrons and we put them into our storage room and we accelerate them into the light and then we don't want smashing into anything because we want to use the radiation they emit when they go through a magnet. 

So, in terms of technology, we're very similar, but in terms of output, we're looking a very different science.

Graihagh -   We're currently in the storage chamber and I can see multiple magnets of all different colours and sizes and cooling equipment and so many different wires.  But this is only one facet of the whole of Diamond.  Perhaps you can talk me through the very beginning of what happens and how we end up here in the storage room.

Ed -   The electron will start their life at the centre of the facility.  So, you look down at Diamond from the sky, you look at this giant spaceship donut.  Inside of the donut, you have a short line and then a small donut, and then the large donut.  The electron starts from the beginning of the short line and the electron, they're fired from a heated cathode and they're then traveling at about walking pace.  Electrons then travel through their proper tube and this is the linear accelerator.  It takes the electron from the initial 90-kilo electron volts up to 100 mega electron volts which is already 99.99% the speed of light. 

Once we are at our operating energy, we head out into the main storage room of which we're sat in now in fact.  We're just up as looking around of curved tunnel to where the electrons likely enter the main storage room.  They then travel around the 560-meter circumference.  They then travel in a vacuum vessel and that vessel is threaded through all of our electron magnets in the main storage room. 

The magnets themselves are kind of big blocks of steel and that creates just a straight magnetic field that then bends the bunch of electrons and keeps them on the orbit in our ring.  It's a little bit like a swing ball set.  Once it turn, the swing ball comes around and you hit it with your bat and the electrons regain the energy that they've lost that they've gone around the storage room. 

As they get bent, they emit very hard x-ray radiation and also lights down into the infrared.  That light, the infrared visible, the x-rays then are sent down through beamlines into experimental stations where scientists do a variety of studies on crystals and other materials to find out their structure.

Graihagh -   What happens in the beamlines?

Ed -   There was a lot of techniques used here.  A lot of beamlines here use crystallography, so they select their energy of x-rays, they will fire them through a small tiny crystal and they'll get a pattern of spots which they can then use to determine the actual structure of the protein or the molecule they're looking at.

Graihagh -   So really, Diamond is like a giant microscope that enables you to see molecular levels of a material.  So, whilst a regular microscope, that you might get in a lab you can then see cells, you can see a much higher fidelity atoms in the placements of atoms within a material.

Ed -   That would be a very broad version brushstroke, there would be an awful lot of computing and an awful lot of science that goes into parts and terminal of these things.  We really are standing on the shoulders of many generation for scientists here.

Ginny -   Physicist Ed Rial speaking with Graihagh Jackson at the Diamond Synchrotron.


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