Welcome to The International Year of Light 2015 – and it’s been quite eventful so far, with plenty more to come I’m sure.
This celebration is sponsored by the United Nations through UNESCO, and the emphasis on ONE WORLD themes and symbolism is very evident. As is that one-eyed look throughout the website.
Here is an extract from that site explaining synchchrotron technology, bearing in mind it is the by-product of CERN.
Lightsources of the world
Light is a key ingredient for large scientific research facilities known as synchrotrons and Free Electron Lasers (FELs). At the heart of one of these giant machines is a particle accelerator which is used to create an incredibly bright light. This light is so intense it can reveal the atomic and molecular detail of the world around us, and is used by scientists the world over for fundamental and applied research into almost every scientific research field imaginable. There are now more than 60 synchrotrons and FELs around the world dedicated to applications in physics, engineering, pharmacology, and new materials, to name but a few. You can browse these pages for information and links to resources that will allow you to explore the remarkable properties of these magnificent machines.
Revealing the world around us
Scientists use synchrotron light to study a vast range of subject matter, from new medicines and treatments for disease to innovative engineering and cutting-edge technology.
Whether it is fragments of ancient paintings or unknown virus structures, scientists can study their samples using a machine that is 10,000 times more powerful than a traditional microscope.
Synchrotrons are amongst the most advanced scientific facilities in the world, and their pioneering capabilities are helping us to find answers to some of the most challenging problems facing us today.
Find out where synchrotron light can make a difference…
A spectrum of possibilities.
‘Light’ refers to the breadth of the electromagnetic spectrum, which includes visible light, as well as light with wavelengths that we cannot see such as: radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays. These different types of light are used in everyday life, however. For example, airport scanners use X-rays to inspect the contents of your suitcase.
The right kind of light and the right equipment can help us see things in much finer detail than the human eye could possibly make out. This capability holds the key to answering some of the fundamental questions about the world around us, such as: what is our planet made from? What are the processes that sustain life? How can we conquer viruses?
These questions can only be answered at the molecular level, and this is where lightsources come in.
Find out more…
Where in the world?
© Diamond Light Source
Visit lightsources.org to find your nearest light source. This dedicated website is the result of collaboration between communicators from light source facilities around the world, and is a regularly updated global resource providing information and updates about light sources, and opportunities for international collaboration.
How do they work?
Lightsources can be compared to a ‘super microscope’, by providing intensely bright forms of X-ray, infrared and ultraviolet light, which enables research on samples in the tiniest detail. Each range of light is suited to a particular job.
To ‘see’ atoms, we need to use a form of light that has a much shorter wavelength than visible light. As a general rule, short-wavelength (hard) X-rays are most useful for probing atomic structure. Again as a general rule, long-wavelength (soft) X-rays and ultraviolet light are good choices for studying chemical reactions. Infrared is ideally suited to studying atomic vibrations in molecules and solids, and at its very long wavelength end (terahertz waves), it is also useful for certain types of electronic structure experiments. The identification of elements in samples is the province of X-rays.
This range of the electromagnetic spectrum is known as ‘synchrotron light’, as it is produced by a dedicated synchrotron machine. A synchrotron light source typically begins with an electron gun, containing a manmade material, to which an electrical and thermal current is applied. This results in electrons ‘lifting off’ and beginning their journey by being propelled down a linear accelerator (linac). They then enter a circular-shaped booster ring, where they are accelerated to relativistic speeds. Finally they enter another ring, often called a ‘storage ring’, where they circulate for hours. The electrons will travel in a straight line, so at points around the ring, special ‘bending’ magnets help them keep to their circular path. As the electrons circulate, powerful magnets keep them bunched together and focused.
Synchrotron light is produced when the electrons change direction around the ring. In synchrotrons, this happens when they are manipulated by bending magnets, or as they pass through insertion devices. At the points where the electrons change direction, they emit a fan of radiation (known as synchrotron light). This radiation branches off the storage ring, and enters laboratories, or ‘beamlines’. Here it is refined with devices such as monochromators and mirrors, before it is shone on the sample, enabling researchers to obtain detailed data about the sample’s structure and behaviour.
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, UK. Now there are over 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.