A synchrotron is a type of circular particle accelerator. It works by accelerating charged particles (electrons) through sequences of magnets until they reach almost the speed of light. These fast-moving electrons produce very bright light, called synchrotron light. This very intense light, predominantly in the X-ray region, is millions of times brighter than light produced from conventional sources and 10 billion times brighter than the sun. Scientists can use this light to study minute matter such as atoms and molecules.
No. Synchrotrons fall into two major categories; high energy physics machines and sources of synchrotron light. They were first developed in the 1950’s to study high energy particle collisions. These particle colliders are still used today; for example, the Large Hadron Collider at CERN. However, since the 1960s, synchrotrons have also been used, not to smash particles together, but to exploit the light produced by high energy particles undergoing acceleration.
Diamond is dedicated to the exploitation of synchrotron light. Each synchrotron is optimised to produce light with a particular energy for specific applications – Diamond produces a 3 GeV (Giga-electron-volt) electron beam, and is therefore classed as a medium energy synchrotron. Newer synchrotrons like Diamond are built on more advanced technology, and so are capable of producing more stable and brighter light.
The history of synchrotrons can be traced back to 1873, when James Clerk Maxwell published his theory of electromagnetism; this theory changed our understanding of light. Some years later in 1895, Wilhelm Rontgen expanded on Maxwell’s theory and identified X-ray light, and by 1906 Charles Barkla had discovered that X-rays could be used as a tool to determine the elements present in gases. In 1912 Max von Laue found another use for X-rays: the beams could help to identify the structure of very small matter, like atoms, based on their crystal structure. In 1913, William Henry and Lawrence Bragg, a father and son team, solved the formula for determining an object’s structure based on the pattern formed by X-rays passing through it. The Braggs’ discovery opened up the field of crystallography, making it possible to investigate the atomic nature of our world.
The first synchrotron, built in 1946, was designed to study collisions between high energy particles. In this role they were very successful, and the Large Hadron Collider at CERN is still dedicated to this purpose. But scientists soon noticed that these machines also had a by-product: they generated very bright light.
In 1956, the first experiments were carried out using synchrotron light siphoned off from a particle collider at Cornell in the USA. Over the years, the number of experiments using synchrotron light increased, but the scientists still had to use the light that was a by-product of particle collider machines; there was no dedicated synchrotron light source. This changed in 1980, when the UK built the world's first synchrotron dedicated to producing synchrotron light for experiments at Daresbury in Cheshire. Now there are around 40 large synchrotron light sources around the world. These scientific facilities produce bright light that supports a huge range of experiments with applications in engineering, health and medicine, cultural heritage, environmental science and many more.
The generation of a synchrotron is related to the technology it uses to produce synchrotron light. Synchrotrons were originally developed as "atom-smashers", used by particle physicists to study the basic constituents of matter.
The synchrotron light produced by these machines was considered a nuisance. However, in the 1960’s, physicists began to think about using the synchrotron light generated by the particle accelerators as a tool to study matter. First generation synchrotrons were built primarily for high-energy particle physics, with synchrotron light experiments performed parasitically. Second generation synchrotrons were solely dedicated to the production of synchrotron light, and used bending magnets to generate synchrotron light; the UK built the first of these at Daresbury in 1980. Third generation synchrotrons are different, because they use special arrays of magnets called insertion devices, which cause the electrons to wiggle, creating even more intense and tuneable beams of light. The next generation of synchrotron is likely to be free electron lasers, which will offer even more advanced capabilities.
All synchrotrons are optimised to produce an electron beam with a specific energy; at Diamond the electron energy is 3 GeV (Giga-electron-volt). This is classed as medium energy. Prior to Diamond being built, consultation with the scientific community highlighted the need for a medium energy source, as the UK already has access to a high energy source, the ESRF in Grenoble. Diamond provides this medium energy source, and due to advances in technology, medium energy synchrotrons can support a very wide range of applications.
There are approximately 70 synchrotrons around the world in various stages of development. There are technical differences between the use and capabilities of synchrotrons, with some being used for appliance and others for fundamental/theoretical research. A list of the main large synchrotrons can be found on the lightsources.org website.
Yes. Diamond has already been used to investigate the structure of sodium at very high pressures. The UK synchrotron has also helped research into the detailed surface properties of magnetic materials, which may have an application in the future.
Yes. Giant magneto-resistance, the phenomenon behind portable mp3 players, was studied using synchrotrons. The anti-flu drug Tamiflu was developed using synchrotron based research, and the structures of many proteins, viruses and vaccines were successfully mapped using synchrotron light. Synchrotrons have also been used to monitor the air at Ground Zero following the attacks on the World Trade Centre, to study the degradation of the Dead Sea scrolls, and to provide a window into our atomic and molecular world.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
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