Interior View of
the Test Facility
The XFEL will be a facility that produces high-intensity ultra-short x-ray flashes. The basic components are an electron source, a 2.1km accelerator tunnel (operating at –271 degrees celsius) and an arrangement of magnets (undulators) that will allow the electrons to travel at close to the speed of light and produce flashes of x-ray laser light. The last kilometre will see the tunnel fan out into five separate tunnels where the x-ray flashes are generated – with an underground experimental hall and, eventually, ten experimental stations.
The x-ray flashes will be on average 10 000 times brighter than conventional x-ray light sources (peak brilliance is billions of times higher). The light pulses’ duration is 100 femtoseconds (thousandths of a millionth of a millionth of a second), allowing them to capture chemical reactions that cannot currently be recorded. The wavelength can be varied from 0.085 to 6 nanometres (billionth of a meter), allowing for details at the atomic level. As the flashes have laser light properties, it will allow for three-dimensional recording.
The brief, intense x-ray pulses will allow scientists to basically film different states of matter at the atomic length and timescale. For the first time, it will be possible to actually film chemical reactions, the atomic details of molecules, and capture three-dimensional images of the nano-world. Imagine being able to actually record and watch the process whereby hydrogen and oxygen combine to form water – that is the potential that XFEL has.
Being able to watch and record accurately at the nano, or atomic, scale opens up a world of research. XFEL research could be of great importance to fields such as materials science, plasma physics, structural biology, geology and chemistry. New technologies and applications could be developed, for example in biomedicine, or in the optimisation of combustion and catalysis technologies.
The basis for XEFL has already been tested. The Free-electron laser facility in Hamburg (called FLASH) started operations at the German Electron Synchroton (DESY) in 2004 (DESY is a German national research centre in Hamburg, and one of the leading accelerator facilities in the world). FLASH has been used for research with shortwave ultraviolet radiation.
FLASH does not have the power and accuracy of XEFL (it will generate a wavelength of up to six billionth of a metre), but it is an important pilot for the XEFL, and until 2009 it will be the only free-electron laser in the world for radiation in the soft x-ray region. At the same time, scientists and engineers will use FLASH to continue development work on a new linear collider for particle physics.
The total cost of the project has been estimated at €1.1 billion (2005 prices). The project is being co-financed by 12 international partners – China, Denmark, France, Greece, Hungary, Italy, Poland, Russia, Spain, Sweden, Switzerland, the United Kingdom, and Germany. Hosting the site, Germany will be covering 75 percent of the costs, and the intention is to form a limited liability company responsible for the construction and operation of XEFL. Having a strong connection to the DESY centre, which is a pioneer in developing superconducting accelerator technologies, it is also hoped that the facilities will attract scientists from across the world.
The European XEFL is also one of the major research infrastructure projects highlighted in the Roadmap published by the European Strategy Forum on Research Infrastructures (ESFRI). The Roadmap, published in October 2006, identifies new research infrastructures, of pan-European interest, which serve the long-term needs of European research communities. Of the 35 projects highlighted in the brochure, XEFL is amongst the top five most expensive and is the first to launch. But besides cost, it is in reinforcing Europe’s place at the forefront of cutting-edge science that XEFL should be conceived.