Diamond is a synchrotron; a huge scientific machine, half a kilometre in circumference, designed to produce very intense beams of X-rays, infrared and ultraviolet light. For centuries, scientists have used microscopes to study things that are too small to see with the naked eye. However, microscopes are limited by the visible light that they use. Optical microscopes can be used to study objects that are a few microns (0.001mm) in size, about the size of cells. However, to study smaller objects like molecules and atoms, scientists need to use the special light generated by the synchrotron.
Synchrotron light can be 10 billion times brighter than the sun. Particles called electrons are generated in an electron gun, very like the cathode ray tubes found in old television sets. They are then fired out into the machine, where they are accelerated up to very high speeds through a series of three particle accelerators. These are called the linear accelerator, or linac, the booster synchrotron and the large storage ring.
The linac and the booster synchrotron both work to accelerate the electrons so that they are travelling at nearly the speed of light. Once they enter the storage ring, the electrons are moving so fast that they could travel around the entire world 7.5 times in a single second.
The storage ring is what gives Diamond its iconic doughnut shape. It has a huge circumference; the footprint of St. Pauls Cathedral could fit inside Diamond 5 times. The storage ring is not a true circle, but a type of polygon called a tetracontakaioctagon, made of 48 straight sections angled together with 48 bending magnets, and this magnetism is used to steer the electrons around the ring. Third generation synchrotrons like Diamond also use special arrays of magnets called insertion devices. These cause the electrons to wiggle around, which produces even more intense light. When the path of the electron beam is bent by Diamond’s powerful magnets, the electrons lose energy in the form of light. This light can then be channelled out of the storage ring and into the experimental stations, called beamlines.
It is inside these beamlines that scientists carry out their experiments. The beamline contains three different sections; the optics hutch, where the light is filtered and focused; the experimental hutch, where the sample sits and the experiment is carried out; and the control cabin, where the scientists control the experiment. The beams of light are so strong that, in the case of Diamond’s X-ray beamlines, it is not safe to be in the same room whilst they are being fired at the sample.
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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