Synchrotrons making the light fantastic
This topic is sponsored by the Australian Government's National Innovation Awareness Strategy, and
the Victorian Department of Innovation, Industry and Regional Development.
The Victorian Government is building a $206 million synchrotron in Melbourne. Why invest so much money in a machine that most people have never heard of?
|You will get more from this topic if you have mastered the basics of atoms and molecules and electromagnetic radiation these links will take you to an annotated list of sites with helpful background information.|
Synchrotrons are particle accelerators massive machines built to accelerate sub-atomic particles to almost the speed of light. They produce synchrotron radiation an amazing form of light that researchers are shining on molecules, atoms, crystals and innovative new materials in order to understand their structure and behaviour. Synchrotron radiation really is the 'light fantastic' because it gives researchers unparalleled power and precision in probing the fundamental nature of matter.
The nature of synchrotron radiation
Synchrotron radiation also referred to as synchrotron light is a type of electromagnetic radiation energy that travels in the form of electromagnetic waves.
What makes synchrotron radiation or light so special? Well, for a start, most devices can only generate one type of electromagnetic radiation. For example, light globes emit visible light, heat lamps emit infrared light and X-ray tubes emit X-rays. Each device emits a set range of wavelengths. Synchrotron radiation extends over a broad range, from the infrared to X-rays. Different parts of this broad spectrum can be used for different purposes.
What’s more, the intensity of light being produced is staggering a million times brighter than sunlight and a billion times greater than the radiation from a typical laboratory X-ray source. This makes synchrotron radiation possibly the most powerful light produced by humans. The emerging beams are extremely fine just a few thousandths of a millimetre across and are emitted in extremely short pulses, typically 10-100 picoseconds in length (a picosecond is a trillionth of a second).
Uses of synchrotron radiation
The uses of synchrotron X-rays are many and range from designing drugs to making micromachines. Let’s explore some of these applications.
Currently the most important use of synchrotron X-rays is X-ray crystallography, a technique first developed by William and Lawrence Bragg. With this technique, X-rays are fired through crystals and the resulting patterns reveal the atomic content and molecular structure of the crystal often a protein. Studies using synchrotron X-rays for protein crystallography can help scientists understand and imitate complex structures from cellulose fibre to spiders' silk.
Analysing viral proteins
Understanding viral proteins is critical when designing new drugs to fight viral disease. For example, the Australian-designed anti-flu drug Relenza was developed following the analysis of a surface protein of the influenza virus using synchrotron X-rays (from a Japanese synchrotron). Synchrotron radiation will be at the centre of the growing revolution in designer drugs for a wide range of diseases. The advantage of using intense X-rays from a synchrotron is that an analysis can now be completed in hours or days instead of the months or years needed when conventional X-rays are used.
Investigating cell structure
Different forms of synchrotron light are being used to capture images of internal cell features that are up to a thousand times smaller than was previously possible. Synchrotron light is also being used to construct high precision 3-D cell maps and to monitor cellular processes as biochemical reactions are taking place.
Lithography for computer chips
X-rays can be focused to such a fine point that they can cut out tiny machine components from silicon or plastic with incredible precision on a scale of thousandths of a millimetre. They can also be used to etch patterns in microchips.
Synchrotron studies are a major foundation of modern materials science. Synchrotron light is being used to develop ceramics, structural composites and a wide range of plastics. It can be used to determine structural and chemical change at the level of individual atoms and molecules in processes such as corrosion and metal fatigue.
The powerful penetrating characteristics of synchrotron light also allow researchers to probe below the surface of electronic devices or to check the integrity of metal joining processes such as welding.
Particle accelerators and types of synchrotrons
The first particle accelerators were built in the 1930s by physicists who were interested in finding out about the elementary particles that make up atoms. These machines atom smashers accelerated particles to tremendous speeds then collided them into an atom, thus breaking the atom into its component parts. In some accelerators the particles were propelled around a circular track, and when the particles were forced to move around the circle, they lost energy by emitting a beam of synchrotron radiation.
This beam made the experiments of the particle physicists difficult to perform (Box 1: The first particle accelerators and synchrotrons). But researchers soon realised that synchrotron radiation was a valuable research tool, and began to use these machines as a source of radiation. They became known as first-generation synchrotrons.
Second-generation synchrotrons were built solely for their ability to generate synchrotron radiation. They were basically circular rings with ports arranged around the outside through which the intense synchrotron radiation passed.
In the last two decades, synchrotron technology has reached new heights. Magnetic devices are now installed within the ring, causing the stream of speeding electrons to oscillate as it passes by. This greatly increases the intensity of the beam. This type of facility is known as a third-generation synchrotron.
Using synchrotron radiation
With third-generation synchrotrons, special magnetic devices such as undulators and wigglers are inserted in straight sections of the machine to give even more intense beams of light than from second-generation synchrotrons. The storage ring containing the accelerating electrons has many ports around it, through which the synchrotron light emerges. Each port opens onto a beamline and each beamline has mirrors and optical devices to manipulate the light. A researcher doing an experiment at a workstation at the end of one beamline can specify the precise form of the radiation to be delivered for the experiment. All beamlines can be operated simultaneously and independently.
The Australian synchrotron, which is a third-generation machine, will initially have nine beamlines but will have the capacity to increase to 35 beamlines in the future, making it possible for 35 completely different experiments to be conducted at the same time. The Australian synchrotron is due to open in 2007 with the first nine beamlines.
Is it worth the cost?
There are few areas of modern research and development where synchrotron light doesn’t have some potential role to play. But is it worth several hundred million dollars of investment? Most Australian research institutions believe it is.
A national facility means we won’t have to rely on limited access to overseas facilities. We’ll have a greater capacity to develop our own projects and provide local industry with dedicated, cutting-edge synchrotron support. And we’ll give our own top scientists a better reason for staying in Australia, while attracting top researchers from overseas.
Page updated February 2006.