The Swiss X-Ray Free-Electron Laser
Brilliant prospects for research into innovative materials and biomolecules
The new large research facility at the Paul Scherrer Institute – the Swiss X-ray free-electron-laser SwissFEL – provides new opportunities for cutting-edge Swiss research.
The major challenges facing our society are to
the ability to follow such fast processes in
find a secure, climate-neutral energy supply,
detail – and, in a certain sense, to film the
to provide long-lasting, affordable health care
action. These sources are based on electron
for an aging population, and to maintain an
accelerators that are able to generate extremely
intact environment that we can pass on to our
short pulses of coherent X-ray light (X-ray light
descendants. Scientists around the world are looking for new industrial processes, new types of substances and materials and new medicines which can help to solve these pressing problems. However, we can only search purposefully for innovations if we understand the underlying mechanisms properly; for example, we need to know the processes associated with a disease in an organism before we can develop drugs that are effective, but free of serious side effects. When scientists investigate such fundamental problems as these, they often come up against questions that are impossible to answer using the currently available research methods. For example, processes occurring in nature, in the human body and in many technical devices are so rapid that although we may be able to see their initial and final states, we cannot follow in any detail what happens in-between. As a result, we are still unable to answer many important questions for the development of better drugs, more efficient energy systems or ultra-fast computers and data storage devices. Sources that work by the X-ray free-electron laser principle (abbreviated to “XFEL”) give us 2
with the properties of laser light). The new large
the USA alone. Researchers will be able to carry
research facility at the Paul Scherrer Institute,
out investigations at the SwissFEL for up to
the SwissFEL, will be one such source. These
5000 hours per year at a number of experimen-
X-ray lasers are research facilities on a huge
scale â€“ the machine used to generate the pulses of X-ray light is housed in a tunnel measuring several hundred metres. When the SwissFEL starts with its first pilot experiments in 2017, it will be one of only five
PSI â€“ experienced with large research facilities
such facilities worldwide. With SwissFEL, PSI
PSI develops, builds and operates unique large
is responding to the growing demand for ex-
research facilities for investigations in the
perimental facilities, which cannot be covered
fields of materials science, physics, chemistry,
with the four X-ray free-electron-lasers then
biology, medicine and energy and environmen-
available in Europe, Japan, South Corea and
Laser specialist Marta Divall working on a vacuum chamber for the experiments which will be conducted in future at the SwissFEL. 3
Beamline designer Bolko Beutner working on the SwissFEL injector test facility. The electron beam generated in the injector has a diameter of a few micrometres. The transverse beam profile monitors, which render the electron beam visible, therefore have to be adjusted precisely.
PSI researchers as well as scientists from uni-
international leader in the development of
versities and industry use these facilities to
modern X-ray light sources with its Swiss Light
carry out experiments. External researchers
Source SLS. The SLS has delivered a large
receive competent and comprehensive support
number of major scientific results since that
from the PSI staff as they put their scientific
time, including the work of the American re-
research plans into action. For this reason, and
searcher Venkatraman Ramakrishnan, for
because of the high technical quality of its
which he received the Nobel Prize for Chemis-
facilities, PSI has gained an excellent world-
try in 2009.
wide reputation as a user laboratory, and its name now stands for cutting-edge research involving demanding, complex interdiscipli-
Setting international standards
nary projects. The institute has carried out pioneering work in many fields, such as energy
PSIâ€™s specialists have now used the compe-
technology for environmentally friendly vehicle
tence they gained from the SLS project to de-
drives and the development of proton therapy.
velop another technologically unique facility,
This treatment method can be used to deal less
the SwissFEL. This, like the SLS, will set inter-
invasively and more successfully with certain
national standards. For example, researchers
types of cancer than would be achievable by
at PSI have developed innovative ideas so that
conventional therapeutic techniques. As far
the SwissFEL can be built more compactly and
back as 2001, PSI had taken on the role of an
less expensively than other X-ray lasers.
the long term, the SwissFEL will strengthen Switzerland’s standing as a research location, while making a simultaneous and substantial contribution to the lasting competitiveness of Swiss industry. This competitiveness is largely based on the ability to bring innovative products onto the market before those of competing companies. The availability of a first-class research potential within an industry’s home country allows it to develop new discoveries at an early stage, along with innovative methods and tools, and hence to stay abreast of the global challenge. Swiss industry will also be able to benefit directly from the new research opportunities at the SwissFEL, whether through collaborative ventures with PSI and universities or through investigations undertaken at the SwissFEL as part of industry’s own development activities. This innovative project will thus further The SwissFEL is also setting new standards
strengthen the good relationships built up over
with its energy concept: it is the world’s first
the past years between PSI and industry.
energy-efficient X-ray free-electron laser,
Even before commissioning, the SwissFEL pro-
thanks to a drastic reduction in its power
ject has benefited Swiss industry: the new
consumption compared to other facilities. In
high-tech equipment was developed and im-
addition, the SwissFEL is the only XFEL to have
plemented in close cooperation with domestic
a heat recovery system. The waste heat from
companies. Partners include, for example,
the SwissFEL is fed into PSI’s heating network.
mechanical and plant engineering specialists TEL Mechatronics AG (formerly Oerlikon Mechatronics AG) and MDC Max Daetwyler AG,
SwissFEL – innovative project strengthens the competitiveness of the Swiss economy
both of which have been tasked with develop-
The SwissFEL is a national facility that is
struction and operation on the training of
strongly oriented towards the research inter-
students, post-graduates and hi-tech special-
ests and expertise of Swiss universities and
ists in areas such as power electronics,
Swiss industry, and takes account of their re-
computer technology, materials processing,
search interests and requirements. In the long
vacuum technology, sensor technology and
term, the construction of the SwissFEL will In
ing and constructing major SwissFEL components. Last but not least, the SwissFEL project will also have a positive effect during its con-
The SwissFEL facility Construction and function
The SwissFEL will generate extremely intense,
sections: an injector, a linear accelerator, an
extremely short flashes of X-ray light for scien-
arrangement of undulators and equipment for
tific experiments. This X-ray light will be emitted
experiments. In the injector, electrons are ex-
within the SwissFEL by fast-moving electrons
tracted from a metal plate by a flash of light
which are directed by powerful magnets to
and are then pre-accelerated by an electric field
follow a narrow, slalom-shaped path. This is
before continuing on to the linear accelerator
because when electrons are forced to change
where they are accelerated to the required
their velocity or direction, they emit electro-
energy by means of powerful microwaves. They
magnetic radiation – depending on the type of
are then sent on a slalom-shaped path in un-
movement of the electron; this could be in the
dulators – the technical name for a periodic
form of radio waves, visible light or the very
arrangement of alternately-oriented magnets.
In the process, the electrons generate an ava-
The SwissFEL facility will stretch over a distance
lanche of increasingly coherent radiation – the
of just under 740 metres and will consist of four
uniquely intense X-ray light of the Swiss-FEL.
Linear accelerator The electrons are accelerated to the required energy.
Injector The electrons are generated and pre-accelerated.
Quadrupole magnet This component guides the electron beam along its path.
Cavities The linear accelerator comprises 104 cavities of 113 annular copper discs each. It has an overall length of 335 metres.
12 undulators, each having 1060 magnets, are
Once the X-ray light has been emitted by the
arranged one behind another over 60 metres
electrons, the electrons are no longer required
at the SwissFEL. The high level of accuracy
and are captured in an electron absorber. The
necessary for guaranteeing good overlap of the
beam of X-ray light, however, is sent to the
electrons and the X-rays along the undulator
experimental stations, where it will be availa-
represents an outstanding achievement in the
ble to researchers for use in their experiments.
art of engineering.
The illustration is not to scale. The undulator is located in a vacuum chamber, allowing the magnets to be brought as close as possible to the electron beam.
Â? Experiments The extremely short and intense X-ray flashes are transported, by mean of optical elements, to the measuring stations where the most diverse experiments are conducted.
The undulators are composed of ultra-strong neodymium magnets. Magnets with alternating polarity direct the electrons to follow a slalomshaped path, generating the X-ray light.
Hi-tech in harmony with nature The SwissFEL was built in the immediate vicinity of the Paul Scherrer Institute, in the Würen-
Respect for the sensitive location
lingen forest. The building is a two-storey build-
The Würenlingen forest is a habitat for numer-
ing. The X-ray light for the experiments is
ous species of animals and plants and also
generated on the lower floor where the injector,
provides valuable recreational space for people
accelerator and undulators are located. The
who live or work in the vicinity. In order to do
supply systems required to operate the Swiss-
justice to this sensitive location, an interdisci-
FEL’s accelerator are located on the upper floor
plinary team of experts has worked on a project
above the accelerator tunnel. The experimental area after the accelerator tunnel is a wider, single-storey building.
Wild animals will be able to circulate undisturbed thanks to two wild animal crossings at the SwissFEL facility.
The supply systems for the SwissFEL accelerator are located on the first floor. A
cele r ac
The X-ray light for the experiments will be generated in the basement, where the injector accelerators and undulators are located.
Habitat for endangered animal species
for two years, developing a concept to achieve the best-possible integration of the SwissFEL within its natural environment. The impacts of the facility on nature and the landscape have
Particular attention has also been paid to en-
been minimized as far as possible by embed-
dangered animal species: tthe Grey Long-Eared
ding it within an ecologically enhanced land-
Bat which has its home nearby is able to find
scape, which will, in turn, result in a new abun-
new food in the vicinity of the SwissFEL. Ponds
dance of species.
and open areas of land, shrubs and hedges
The facility is mostly covered with earth, so that
combine to form an appropriate natural habitat
forest users only see a sloping hillside. Rough
for threatened amphibians.
grassland, a natural landscape indigenous to
Wild animals are able to circulate without im-
Aargau, has been planted on the hillside,
pediment thanks to two wild animal crossings.
creating a habitat for butterflies and wild bees.
Vehicular transport to and from the facility is kept to an absolute minimum on a low-lying road which is barely visible from the nearby forest path and does not affect forest usersâ€™ enjoyment. The access lightning is only activated when required.
Laboratories will be made available to researchers at the SwissFEL for the duration of their experiments.
View north: The surroundings of the SwissFEL following completion of the facility. The SwissFEL buildings are hidden under the sloping hillside on the left-hand side and are not visible from the forest track. Ecologically valuable rough grassland has been planted on the hillside.
Examples of applications of the SwissFEL X-ray light
The SwissFEL makes it possible to see short-
ing of how they work. Understanding these
term changes in atomic and molecular struc-
details will help us to develop catalysts that
tures. Two examples will illustrate the applica-
convert one substance into another in a more
tion of this special X-ray light.
environmentally-friendly and energy-saving way. The fact that we don’t yet understand the de-
The foundations for a sound environment and a secure, climate-neutral supply of energy
tails of catalysis is due in part to the extremely
Consider, for example, waste gas scrubbing or
reform in a fresh molecule is often just 0.1
the manufacture of raw materials for the chem-
millionth of a millionth of a second. In order to
ical industry. Countless technical processes
properly understand the reaction processes,
involve the conversion of one substance into
scientists need to observe the short-lived in-
another by means of a chemical reaction.
termediate states in a chemical reaction, i.e.
Special substances – which chemists call cat-
to record a kind of a film with an extremely short
alysts – are used to ensure that these reactions
image exposure time. This is exactly what the
proceed as efficiently as possible. The catalysts
SwissFEL will enable them to do: by generating
take part in the reactions but are not consumed
intense X-ray light flashes lasting just 10 fem-
by them. Even though catalytic reactions have
toseconds (1 femtosecond = 0.001 millionth of
been used for many decades in countless ap-
a millionth of a second), individual steps in the
plications, we often lack a detailed understand-
reaction can effectively be “frozen”.
high speed at which chemical reactions take place; the time required for bonds in an individual molecule to be broken and for them to
X-ray pulses H2
Flash of light
Reaction time [fs]
Production of ammonia from hydrogen and nitrogen: ammonia is one of the basic materials used in the manufacture of artificial fertilizers and therefore makes an important contribution to global nutrition. The reaction involved in the production of ammonia proceeds in several stages: initially, the existing nitrogen molecules (blue) and hydrogen molecules (yellow) – each of which comprises two atoms – need to be separated into their component atoms. One nitrogen atom then combines with three hydrogen atoms to form an ammonia molecule. This reaction can only succeed with the help of a catalyst – in this case iron (grey). Although this is a well-understood reaction, it will be used as an example at the SwissFEL, in order to check the scientific potential of the facility. In this way, the scientists will learn to observe similar reactions on similarly appropriate catalysts. In a SwissFEL experiment, the catalytic reaction will be initiated by a flash of light at the beginning and then illuminated by X-ray pulses at various times to map the current status of the reaction at that time. Like this it will be possible to determine the sequence of the various stages of the reaction or the duration of each. 10
The movement of the myoglobin molecule (from position 1 to position 2), which is responsible for vital processes in breathing. We can predict this movement by computer using suitable calculation methods. The new SwissFEL facility will enable us to experimentally check such theoretical models for the very first time.
The foundations for long-term health by tailor-made drugs Proteins form the basic building blocks of living organisms, and are responsible for countless processes vital to life. Many proteins carry out a catalytic function for chemical reactions, while others interact with hormones and signal molecules to control the behaviour of cells and entire organs. A protein molecule has a complicated structure made up of many thousands of atoms; these have to be arranged in a unique configuration in order that the molecule can carry out its task. In doing so proteins are not rigid bodies within a living cell; they undergo movements lasting between femtoseconds and a few seconds.
are very difficult to investigate using this pro-
Ultra-short X-ray flashes, such as those gener-
cess; these are membrane proteins which are
ated by the SwissFEL, will allow scientists to
embedded in the outer skin of the cells. This
follow the movements of molecules over time
is why we do not know the structure of many
and to observe the processes in which these
membranes proteins. In addition to membrane
molecules are involved. For example, future
proteins, the SwissFEL will also provide an
experiments could contribute to our under-
efficient way of investigating the structures of
standing of the molecular processes that play
entire protein complexes, which occur in many
a role in infectious diseases, or diseases that
different forms within cells and organs. Such
restrict function of the cells in organs such as
investigations are not possible using conven-
the nervous system, the joints and the diges-
tional protein crystallography. The SwissFEL
tive organs or tumour diseases. The results will
also allows us to observe proteins acting as
in future enable the production of tailor-made
catalysts, so called enzymes, while “at work”.
These enzymes affect important chemical con-
The spatial structure of proteins can already
versions and facilitate the progress of chemical
be investigated with great success using the
reactions, and the targeted manufacture of
method of protein crystallography at the Swiss
chemical or biological molecules. The Swiss-
Light Source (SLS). However, these measure-
FEL’s high time-resolution capability will make
ments provide only static images of these
it possible to directly observe the individual
complex biological “machines”. However, there
steps in reactions such as the break-up and
is a large number of important proteins that
re-formation of chemical bonds. 11
How fast is “ultra-fast”?
If we want to be able to observe ultra-fast
react. This is about a million times faster than
processes, we need ultra-short X-ray flashes,
the exposure time of a normal camera! By
such as those that will be produced by the
comparison, pictures taken by the SwissFEL
SwissFEL, lasting for about 10 femtoseconds.
will be shot another million times faster than
How can we get a feel for this short time inter-
Lucky Luke can draw. In other words: the Swiss-
val? Recall the comic hero Lucky Luke, who
FEL has an exposure time of 10 femtoseconds,
could draw his gun “quicker than his own
which is a thousand billion times faster than a
shadow”. To perform this feat, how fast does
Lucky Luke really have to be? Since light requires about 10 nanoseconds to cover a distance of 3 metres, Lucky Luke has this much time to draw his gun before his shadow will
Using the SwissFEL to “photograph” the way molecules form a new compound
Lucky Luke, quicker than his own shadow 10 femtoseconds (0.00000000000001 s)
Photography with a normal camera 10 nanoseconds (0.00000001 s)
10 milliseconds (0.01 s)
Technical information about the SwissFEL Length: approx. 740 metres Final energy of electrons: 6 giga electron volts (billion electron volts) Repetition rate: 100 Hz (pulses per second) Number of accelerated electrons per pulse: 2 × 1 250 000 000 (two electron bunches) Wavelength of X-ray light: between 0.1 and 7 nanometres, depending on the beam line Duration of an X-ray pulse: 1–60 femtoseconds (1–60 × 10–15 s) Brilliance: almost 10 billion times the peak brilliance of a modern synchrotron radiation source Availability for experiments: approx. 5000 hours per year First pilot experiments: 2017 Cost: The cost of constructing SwissFEL will be approximately CHF 275 million, the majority of which will be borne by the Swiss federal government. The Canton of Aargau is also making a financial contribution of CHF 30 million from its Swisslos Fund.
Site of the SwissFEL at the Paul Scherrer Institute
Swiss Light Source SLS The SLS is a synchrotron light source which has been used for top-level research since 2001. The SwissFEL The SwissFEL will complement the research opportunities at the SLS.
Central control Control room for all PSI‘s accelerator facilities. In future the SwissFEL will also be controlled from here.
Birdâ€™s-eye view of the Paul Scherrer Institute.
PSI in brief
The Paul Scherrer Institute PSI is a research institute for natural and engineering sciences, conducting cutting-edge research in the fields of matter and materials, energy and environment and human health. By performing fundamental and applied research, we work on sustainable solutions for major challenges facing society, science and economy. PSI develops, constructs and operates complex large research facilities. Every year more than 2500 guest scientists from Switzerland and around the world come to us. Just like PSIâ€™s own researchers, they use our unique facilities to carry out experiments that are not possible anywhere else. PSI is committed to the training of future generations. Therefore about one quarter of our staff are post-docs, post-graduates or apprentices. Altogether PSI employs 2000 people, thus being the largest research institute in Switzerland.
Cover picture: The Daetwyler Group developed and built essential components for the undulators of the Swiss X-ray Free Electron Laser SwissFEL: Peter Daetwyler (left) with SwissFEL project leader Hans Braun in the beam tunnel in front of the undulators, ready for operation.
Imprint Concept/Editing Paul Scherrer Institute Photography Frank Reiser, PSI Markus Fischer, PSI Design and layout Monika BlĂŠtry, PSI Printing Paul Scherrer Institute Available from Paul Scherrer Institute Events and Marketing 5232 Villigen PSI, Switzerland Telephone +41 56 310 21 11 Villigen PSI, May 2017
More information about the SwissFEL is available from: SwissFEL Project Manager, Accelerator Dr. Hans Braun Tel. + 41 56 310 32 41 email@example.com SwissFEL Project Manager, Experiments Dr. Luc Patthey Tel. +41 56 310 45 62 firstname.lastname@example.org SwissFEL Science Officer Dr. Mirjam van Daalen Tel. + 41 56 310 56 74 email@example.com A film about the SwissFEL can be seen at www.psi.ch/en/media/film-swissfel 15
Paul Scherrer Institut :: 5232 Villigen PSI :: Switzerland :: Tel. +41 56 310 21 11 :: www.psi.ch
Published on Jun 19, 2012
Published on Jun 19, 2012
The Paul Scherrer Institute is planning to construct a new scientific large-scale facility – the SwissFEL X-ray free electron laser. This wi...