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Welcome to the Wonderful World of Daresbury

Updated Tuesday 26th February 2008

Paul Hatherly explains how the synchrotron radiation source is able to unravel tales from the pigments of historic artefacts.

We’re here, and ready to get going at Daresbury Laboratory. Before I tell you about the place, let me introduce you to the team. Maria Gallagher is a Visiting Fellow at the Open University, and has joined me in previous runs at Daresbury. She's a veteran at this game, and has come equipped with the coffee! Nicola Freebody is a Project Student at the University of Reading, and is a Daresbury "novice" - she'll get the night shifts!!! And very importantly, Nigel Poolton from Aberystwyth University, who designed the key piece of apparatus we'll be using, and will be making sure we don't break it!

Roman Wall Plaster Team Copyrighted image Icon Copyright: Paul Hatherly
The Roman Wall Plaster Team with a small part of the machine. [Image: Paul Hatherly] Top – Nigel Poolton. Bottom – Maria Gallagher (left) and Nicola Freebody (right)

So, on to the Daresbury machine, the SRS, itself. What's so special about this, and why do we have to drag ourselves away from our homes? Well, the SRS is one of a few machines in the world which exploits the phenomenon of synchrotron radiation. A good analogy to synchrotron radiation might be to think about a car going round a corner at high speed - the tyres squeal! In a synchrotron radiation machine, electrons (negatively charged components of atoms) are accelerated close to the speed of light in a circular vacuum tube, and kept moving in a circular path by strong magnets. Now, when the high speed electrons are forced to turn by the magnets, they “squeal”, but not in sound, but light. This light is synchrotron radiation. Why is this special? Light comes in many forms - optical, from a light bulb, lower energy infra-red, from heat lamps (also used in surveillance) and higher energy ultraviolet, in tanning lamps (and from the Sun!). But light goes further! If you go to lower energy than infra-red, you come to microwaves and radio, and, interestingly for us, if you go to higher energy than ultraviolet, you end up with x-rays and gamma rays. Normally, for each type of light, you would need a different lamp or source. Uniquely, synchrotron radiation has all energies of light in it, which is why people build these machines, and why so many people want to use them for so many purposes.

The Daresbury synchrotron Creative commons image Icon ofey under CC-BY-NC-ND licence under Creative-Commons license
The Daresbury synchrotron in action

We now need to connect this advanced light source to our Roman material. What we will be doing is shining x-rays of particular energies on to our Roman paint. The energy from the x-rays will be dumped into the material of the paint, and eventually come out as visible light which we can easily detect. As we change the x-ray energy, we home in on particular types of atom in the paint, and as we look at the colours of light emitted, we learn about how the atoms are arranged in the material. So we don’t just learn about what is present, but how it is combined with other atoms. More than that, the apparatus designed by Nigel Poolton images the material through a microscope, so uniquely we can get all the information we need at different points on the surface - important, as we may have a mix of different paints - especially if the painters were ripping off their customers!

Better get on now, and get everything ready to roll! In my next post, we should have some first results, and I can show you some pictures. I will also introduce you to a few of the other researchers here, and tell you a little of their work.

Bye for now,

Paul.

 

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