Synchrotron's bright spark

When, on the eve of ‘Big Bang Day’, former UK chief scientist Sir David King called for a re-evaluation of scientific priorities, his comments were widely interpreted as a criticism of the £4bn Large Hadron Collider (LHC).

While some dismissed him as a party pooper, others asked whether the world’s scientific resources might be better spent on poverty and climate change, rather than the search for an elusive sub-atomic particle.

There is one notable absentee from the debate: the LHC itself which, laid low by faulty wiring, must wait to demonstrate its worth.

But as the arguments continue, an enormous space-age structure in the heart of the English countryside is testament to the fact that giant physics experiments and the real world are not necessarily mutually exclusive.

The Diamond synchrotron at Harwell in Oxfordshire, built at a cost of £350m, is the UK’s biggest scientific project. Since opening early last year it has welcomed a torrent of researchers through its doors, keen to use its dazzling beams of light to probe everything from the molecular structure of proteins to the stresses in aero-engines.

The instrument works by accelerating bunches of electrons around a 500m circumference storage ring. At just below the speed of light, these electrons are passed through magnets called insertion devices that cause them to wiggle and produce intense bursts of light.

Ranging from ultra-violet to infrared and X-rays 100 billion times brighter than those used in hospitals, this light is channelled down tubes called beamlines to experimental stations set up to probe matter with a range of advanced optical techniques.

Keeping a watchful eye over much of this activity is Prof Trevor Rayment, Diamond’s new director of physical sciences. A physical chemist and a long-serving member of the UK’s ‘synchrotron community’, Rayment is keen to expound on the real-world applications of Diamond.

‘The range of problems we want to look at is just awesome,’ said Rayment, challenging The Engineer to name an area of engineering where synchrotrons could not make a contribution.

His eyes light up at up at our somewhat predictable suggestion of ‘automotive engineering’.

‘That’s too easy,’ he said. ‘Let’s think about the steel. If you want to know the stresses and strains within the pistons then you can actually map the strain through a piston and engine body. If you want to look at the wear inside the engine then you can use surface science techniques and probes to look at the composition of the wear inside. If you want to study lubrication you could use a variety of techniques to look at those thin films.’

Clearly this capability extends to all engineered components. For instance, in the field of aerospace, Prof Phil Withers of Manchester University’s Aerospace Research Institute is using the facility to carry out tomographic strain and stress mapping of aero engine blades (The Engineer, 7 May).

Diamond is also expected to yield breakthroughs that could benefit the world of electronics, with high-resolution X-ray diffractometry techniques enabling scientists to study the intimate details of a material’s electronic structure.

Diamond’s latest tool, the Small Molecule Single Crystal Diffraction Beamline, made its debut last month, and was used by a group of Bath University researchers to study the structures of metal organic frameworks — polymer-like materials that can act as sensors and have possible future applications in the electronics industry.

Work has also begun on building the Joint Engineering, Environmental and Processing beamline facility which, once complete, will enable dense engineering components weighing up to 2 tonnes to be placed under Diamond’s X-ray beam.

It will allow researchers to understand better how components are affected by production processes and treatments and how products and systems react to strain, ageing or fatigue.

The facility can also be used as a spectroscopic tool. One of the first beamlines was an X-ray spectroscopy beamline, a technique that has been used for studies ranging for the analysis of samples brought back by NASA’s Stardust comet sample return mission, to an Imperial College project looking at the relationship between hip implants and the human body.

Though Diamond’s host of practical applications are far removed from the ‘blue-sky’ physics of the LHC, Rayment admits that synchrotron researchers owe the world of particle physics a debt of gratitude.

‘We have benefited from the investment in particle physics… the LHC is a long-term project and they needed to start planning for it 20 years ago.

‘What that meant is that it gave the motivation for sustained developments in science and engineering and there have been a lot of spin-offs along the way that other people have looked at and said, well I can use that.’

Until the construction of the UK’s first dedicated synchrotron light source at Daresbury in 1980, synchrotron light had been a largely unexplored by-product of experiments carried out on particle accelerators. Synchrotron researchers had to wait patiently in line until the particle physicists took a break. ‘If you look at the beginning of synchrotrons they emerged from redundant particle physics research facilities. We have benefited because we’ve been able to take over stuff they can no longer use,’ said Rayment.

As synchrotron research has gathered pace, it has increasingly broken away from these roots. ‘You can look through history and see how we’ve benefited but we are now independent from particle physics and we are taking many of those tools and developing them in whole new ways.’

The fundamental engineering challenges are now quite different, said Rayment. ‘Particle physics tends to accelerate quite heavy things — protons — whereas we’re concerned about controlling the properties of electrons as they move around. And because they’re 200,000 times lighter they need different engineering to get them to behave the way they do.’

Although there is a great deal of sympathy for the scientists and engineers now struggling to get LHC back up and running, Diamond is now at the forefront of a field that is certain of its own usefulness.

‘We’ve got our feet thoroughly on the ground,’ said Rayment. ‘One of the things we are aware of is that the funding from the government is focused upon applications. We’re aware of the themes that the funding councils are being pushed towards, and we’re conscious that we take taxpayers’ money and so we’re playing our part — partly because that’s where the money is but partly because that’s what we want to do anyway.

‘We’re conscious of the fact that many millions of pounds have been spent on this facility and that people look at us and say, what are you doing? We know we’re there to be critiqued and scrutinised and we’re making sure that what we do is as good and as relevant as it can be.’