The SwissFEL X-ray laser will generate extremely short, intense X-ray pulses to provide completely new insights into the processes taking place within materials and into the structure of the type of molecules that are essential to life. The resulting findings will contribute to the development of more efficient processes in the chemical industry, faster computers and new medicines. The experimental opportunities at SwissFEL take into account the needs of Swiss universities and Swiss industry, allowing the facility to make an important contribution to Switzerland’s standing as a hi-tech location.
The Paul Scherrer Institute (PSI) is planning to build a new large-scale scientific facility – the SwissFEL X-ray laser. This facility will open the door to discoveries in many areas of current research that cannot be obtained using existing methods. The unique properties of the SwissFEL will enable experiments to be carried out at a very high resolution in both time and space. For example, it will be possible to observe the progress of extremely fast chemical and physical processes, including details down to the scale of a molecule or even a single atom. Not only will this result in a significant increase in knowledge – it will also provide the basis for a vast range of technical and scientific developments.
SwissFEL – the facilityWhen fast-moving electrically-charged particles are forced to change their speed or direction of travel, they generate electromagnetic radiation. Depending on their structure, this could be in the form of radio waves, visible light or X-ray light. The SwissFEL makes use of this physical principle. In the SwissFEL, X-ray light is emitted from electrons moving at almost the speed of light. These are forced by devices called magnet undulators – special combinations of many magnets – onto a wave-shaped path. The special feature of an XFEL is not only that the electrons generate X-ray pulses, but also that the X-ray light exerts a countereffect on the electrons. The electrons and X-ray light see-saw backwards and forwards against each other in such a way that they produce a snowball effect, which leads to the generation of laser-quality X-ray light. The electrons are speeded up in advance to the required high velocity by a combination of several accelerators. The X-ray light is then transmitted with the help of special optical elements to the experimental stations, where it shines on the objects to be examined. Each component is unique and represents the very highest level of technical achievement. For example, the magnet undulators measure a total length of 60 metres and are made up of several thousand magnets, all of which have to be aligned to an accuracy of a fraction of a millimetre.
The plan is to build the 700-metre long SwissFEL next to the existing site of the Paul Scherrer Institute in the Canton of Aargau. The facility is expected to come into operation in 2016. The overall cost is estimated to be CHF 275.5 million. The initial stages of the accelerator for the SwissFEL will be tested at a test facility that has been set up in a special experimental hall on the Paul Scherrer Institute’s site during 2010.
Short pulses of light reveal what nobody has ever seen before
These special insights are made possible by the extremely short and extremely intense pulses of X-ray light that will be generated by the SwissFEL. Because the pulses only last for 10 to 60 femtoseconds (1 femtosecond = 0.000 000 000 000 001 seconds), it will be possible to record very fast processes as they are happening. In a chemical reaction, for example, the individual steps can be observed as the molecules in a substance dissolve and the atoms subsequently join together to form new molecules. In other experiments, researchers will be able to see how the direction of magnetism changes in a magnetic material – a process that is crucial to the storage of information on magnetic media.
However, these pulses are not just short; they are also very intense and highly focused. The professionals in this field talk about a high “peak brilliance”, referring to the level of brightness during the pulse. This will be ten billion times higher than the brilliance of the best sources of X-ray light currently available for similar investigations – such as the Paul Scherrer Institute’s own synchrotron light source, known as the Swiss Light Source or SLS. In experimental terms, this high peak brilliance means that the sample will not just be illuminated for a very short time, it will also be illuminated intensely enough that extremely comprehensive information can be obtained about the processes and structures observed during this short interval.
Very fine structures (such as the distance between two atoms) can only be observed using X-ray light, which is why the SwissFEL will generate X-ray light. Not only will it be important for observing atoms during chemical reactions, it will also, for example, be vital for investigations into the structure of protein molecules, where it will be possible to establish the exact arrangement of the atoms by means of a single SwissFEL pulse in each case. Researchers will then be able to determine the structures of many molecules which are vital to life, but which are not accessible by means of the processes that are currently available.
For Swiss universities and Swiss industry
Many of the research results produced at the SwissFEL may well lead to important innovations in a large variety of different sectors, just as the examples of research topics referred to above can be expected to result in more efficient, energy-saving processes in the chemical industry, faster, smaller computers or new tailor-made drugs with few side effects. These applications may be the product of pure research carried out by universities, which concentrates on the fundamental understanding of the processes, or of industrial research, which takes a targeted approach to finding solutions to particular technological or medical problems. The SwissFEL offers researchers from universities and from industry equal opportunities to carry out experiments. They can choose between a number of different cooperation models. The success of this tried-and-tested approach is clearly demonstrated by the huge demand for testing slots at the PSI’s current large-scale facilities and the many important results that have been achieved there.
An important component of the international research network
The SwissFEL is an example of an XFEL facility (where the “FEL” stands for free electron laser and the “X” for X-rays). The first such XFEL in the world was the LCLS in Stanford, California, which began operation in 2009. Two further facilities are currently under construction: the first is in Japan and the other (the European XFEL) is an international project in Hamburg. The SwissFEL will benefit from the experience of these other facilities in many ways, but will also incorporate many innovative ideas from the Paul Scherrer Institute, which will ensure that it is a unique facility. The PSI is also developing vital components for the pan-European project – a sign of the international confidence in the PSI’s technologies. At the same time, this collaboration also offers PSI researchers the opportunity to gather experience for the development of the SwissFEL. In contrast to the European XFEL, particular attention will be paid during the design of the SwissFEL to ensuring that the research opportunities on offer will meet the needs of Swiss researchers and businesses and that sufficient test slots will also be available for their use.
