The European X-Ray Free-Electron Laser Facility (European XFEL) is an

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

research

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

facility commissioned during 2017. The first laser pulses were produced in May 2017 and the facility started user operation in September 2017. The international project with twelve participating countries; nine shareholders at the time of commissioning (Denmark, France, Germany, Hungary, Poland, Russia, Slovakia, Sweden and Switzerland), later joined by three other partners (Italy, Spain and the United Kingdom), is located in the German federal states of

Hamburg Hamburg (, ; ), officially the Free and Hanseatic City of Hamburg,. is the List of cities in Germany by population, second-largest city in Germany after Berlin and List of cities in the European Union by population within city limits, 7th-lar ...

and

Schleswig-Holstein Schleswig-Holstein (; ; ; ; ; occasionally in English ''Sleswick-Holsatia'') is the Northern Germany, northernmost of the 16 states of Germany, comprising most of the historical Duchy of Holstein and the southern part of the former Duchy of S ...

. A

free-electron laser A free-electron laser (FEL) is a fourth generation light source producing extremely brilliant and short pulses of radiation. An FEL functions much as a laser but employs relativistic electrons as a active laser medium, gain medium instead of using ...

generates high-intensity

electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...

by accelerating electrons to relativistic speeds and directing them through special magnetic structures. The European XFEL is constructed such that the

electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

s produce X-ray light in synchronisation, resulting in high-intensity X-ray pulses with the properties of

laser light A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

and at intensities much brighter than those produced by conventional

synchrotron A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The strength of the magnetic field which bends the particle beam i ...

light sources.

Location

The long tunnel for the European XFEL housing the

superconducting Superconductivity is a set of physical properties observed in superconductors: materials where electrical resistance vanishes and magnetic fields are expelled from the material. Unlike an ordinary metallic conductor, whose resistance decreases g ...

linear accelerator A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear ...

and

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...

beamlines runs underground from the site of the

DESY DESY, short for Deutsches Elektronen-Synchrotron (English: ''German Electron Synchrotron''), is a national research centre for fundamental science located in Hamburg and Zeuthen near Berlin in Germany. It operates particle accelerators used to ...

research center in Hamburg to the town of Schenefeld in Schleswig-Holstein, where the experimental stations, laboratories and administrative buildings are located.

Accelerator

Electrons are accelerated to an energy of up to 17.5 GeV by a long linear accelerator with superconducting RF-cavities. The use of superconducting acceleration elements developed at

allows up to 27,000 repetitions per second, significantly more than other X-ray lasers in the U.S. and Japan can achieve. The electrons are then introduced into the

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

s of special arrays of magnets called

undulator An undulator is an insertion device from high-energy physics and usually part of a larger installation, a synchrotron storage ring, or it may be a component of a free electron laser. It consists of a periodic structure of dipole magnets. These ca ...

s, where they follow slalom like trajectories resulting in the emission of X-rays whose wavelength is in the range of 0.05 to 4.7 nm.

X-ray laser

The X-rays are generated by self-amplified spontaneous emission (SASE), where electrons interact with the radiation that they or their neighbours emit. Since it is not possible to build mirrors to reflect the X-rays for multiple passes through the electron beam gain medium, as with light lasers, the X-rays are generated in a single pass through the beam. The result is spontaneous emission of X-ray photons which are coherent (in phase) like laser light, unlike X-rays emitted by ordinary sources like

X-ray machine An X-ray machine is a device that uses X-rays for a variety of applications including medicine, X-ray fluorescence, electronic assembly inspection, and measurement of material thickness in manufacturing operations. In medical applications, X-ra ...

s, which are incoherent. The peak brilliance of the European XFEL is billions of times higher than that of conventional X-ray light sources, while the average brilliance is 10,000 times higher. The higher electron energy allows the production of shorter wavelengths. The duration of the light pulses can be less than 100

femtosecond A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. A femtosecond is to a second, as a second is to approximately 31.6 ...

Instruments

There are seven instruments at European XFEL, run by scientists from all over the world.

Femtosecond X-ray Experiments (FXE)

The FXE instrument allows ultrafast pump-probe experiments on time scales of less than 100

femtoseconds A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. A femtosecond is to a second, as a second is to approximately 31.6 ...

The research emphasis of FXE is on the measurement of ultrafast, often nonlinear chemical or biochemical reactions of samples in solutions or condensed matter with hard

radiation. The instrument comprises two independent X-ray emission

spectrometer A spectrometer () is a scientific instrument used to separate and measure Spectrum, spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomeno ...

s, which can be used at the same time with a large-area 1 megapixel

detector A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

for

scattering In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

examinations. To excite samples, the instrument additionally has an ultra-fast

that can be used from ultraviolet (UV) to infrared (IR).

High Energy Density (HED) and HIBEF UC

The instrument has been developed together with the HIBEF user consortium (HIBEF UC) a unique platform for experiments in which matter can be investigated under extreme pressure, temperature or electrical field conditions using hard X-rays. HED and the HIBEF user consortium have access to high-energy optical

s and pulsed

magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...

s. Scientific applications include the investigation of matter such as that found inside

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

s, high-density plasmas and matter under extreme

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

s or high magnetic fields. The first user experiment took place in May 2019. Since then, further devices have been put into operation and optimised, such as the focussing, the spectrometer, the

monochromator A monochromator is an optics, optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. The name is . Uses A device that can ...

s and the sample environments. The HIBEF user consortium has contributed a second experimental chamber with

diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

anvil cells as well as special laser systems and a laser shock device.

Single Particles, Clusters, and Biomolecules & Serial Femtosecond Crystallography (SPB/SFX)

The instrument Single

Particle In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from s ...

Clusters may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Cluster II (spacecraft), a European Space Agency mission to study the magnetosphere * Asteroid cluster, a small ...

, and

Biomolecule A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. Biomolecules include large macromolecules such as proteins, carbohydrates, lipids ...

s & Serial Femtosecond

Crystallography Crystallography is the branch of science devoted to the study of molecular and crystalline structure and properties. The word ''crystallography'' is derived from the Ancient Greek word (; "clear ice, rock-crystal"), and (; "to write"). In J ...

(SPB/SFX) can provide data on objects in the micrometre range up to atomic resolution.

Soft X-ray port (SXP)

Spectroscopy and Coherent Scattering (SCS)

SCS is the soft X-rays spectroscopy and scattering instrument of the European XFEL. The scientific interest of SCS is focused on the exploration of light-induced transient phenomena in quantum materials as well as in molecules. The beamline hosts a soft X-rays grating monochromator for monochromatic operations. The instrument is equipped with three main end-stations that can be coupled to different experimental probes: * Chemistry chamber (CHEM) equipped with a liquid jet apparatus to study diluted samples, molecules and chemicals. * Forward-scattering Fixed-Target (FFT): a solid samples chamber equipped with an

electromagnet An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire (likely copper) wound into a electromagnetic coil, coil. A current through the wire creates a magnetic ...

, optimized for transmission spectroscopies, small angle X-ray scattering (SAXS), coherent diffraction imaging (CDI) and X-ray photon correlation spectroscopy (XPCS). * X-ray diffraction (XRD) chamber for solid samples equipped with a six degrees of freedom in-vacuum diffractometer. The CHEM and XRD chambers can be couple with a high-resolution resonant inelastic X-ray scattering spectrometer to perform pump and probe RIXS experiments with a very high energy and temporal resolution. The FFT and CHEM chambers can be both coupled to a forward scattering DEPMOS Sensor with Signal Compression (DSSC) detector. SCS offers a variety of different optical sources to be used as a pump to induce transient states or photoactivated reactions in the samples. All the end-stations are equipped with an optical laser in-coupling which allows for spatial and temporal overlap of the X-rays and optical laser pulses at the interaction point.

Small Quantum Systems (SQS)

The SQS instrument is developed to investigate fundamental processes of light-matter interaction in the soft X-ray wavelength radiation. Typical objects of investigation are in the range from isolated atoms to large bio-molecules, and typical methods are variety of spectroscopic techniques. The SQS instrument provides three experimental stations: * Atomic-like Quantum Systems (AQS) for atoms and small molecules * Nano-size Quantum Systems (NQS) for clusters and nano-particles * Reaction Microscope (SQS-REMI) enabling the complete characterization of the ionization and fragmentation process by analyzing all products created in the interaction of the target with the FEL pulses Photon energy range between 260 eV and 3000 eV (4.8 nm to 0.4 nm). The ultrashort FEL pulses of less than 50 fs duration in combination with a synchronized optical laser allow for capturing ultrafast nuclear dynamics with very high resolution.

Materials imaging and dynamics (MID)

The scope of the MID instrument are material science experiments using the unprecedented coherent properties of the X-ray laser beams of the European XFEL. The scientific applications reach from condensed matter physics, studying for example glass formation and magnetism, to soft and biological material, such as colloids, cells and viruses. ;Imaging Imaging covers a broad range of techniques and scientific fields, from classical phase-contrast X-ray imaging to coherent X-ray diffraction imaging ( CXDI) and with applications, e.g. in strain imaging inside nanostructured materials to bio-imaging of whole cells. In many cases the aim is to obtain a 3D representation of the investigated structure. By

phase retrieval Phase retrieval is the process of algorithmically finding solutions to the phase problem. Given a complex spectrum F(k), of amplitude , F (k), , and phase \psi(k): ::F(k) = , F(k), e^ =\int_^ f(x)\ e^\,dx where ''x'' is an ''M''-dimensional spat ...

methods it is possible to pass from the measured

diffraction Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation ...

patterns in

reciprocal space Reciprocal lattice is a concept associated with solids with translational symmetry which plays a major role in many areas such as X-ray diffraction, X-ray and Electron diffraction, electron diffraction as well as the Electronic band structure, e ...

to a real space visualization of the scattering object. ;Dynamics Complex nanoscale dynamics is an ubiquitous phenomenon of fundamental interest at the forefront of condensed matter science, and comprises a multitude of processes from visco-elastic flow or dissipation in liquids and glasses to polymer dynamics, protein folding, crystalline phase transitions, ultrafast spin transitions, domain wall dynamics, magnetic domain switching and many more. The extremely brilliant and highly coherent X-ray beams will open up unseen possibilities to study dynamics in disordered systems down to atomic length scales, with timescales ranging from femtoseconds to seconds using techniques such as XPCS.

Control

The experiments in the facility are controlled via the in-house developed control system named '' Karabo''. It is a distributed

SCADA SCADA (an acronym for supervisory control and data acquisition) is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also cove ...

system written in C++ and python.

Research

The short laser pulses make it possible to measure chemical reactions that are too rapid to be captured by other methods. The

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

of the X-ray laser may be varied from 0.05 to 4.7 nm, enabling measurements at the

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

ic length scale. Today, three

beamlines with seven instruments can be used. Later this will be upgraded to five photon beamlines and a total of ten experimental stations. The experimental beamlines enable unique scientific experiments using the high intensity, coherence and time structure of the new source to be conducted in a variety of disciplines spanning

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

materials science Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials sci ...

biology Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, History of life, origin, evolution, and ...

and

nanotechnology Nanotechnology is the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). At this scale, commonly known as the nanoscale, surface area and quantum mechanical effects become important in describing propertie ...

History

The

German Federal Ministry of Education and Research The Federal Ministry of Research, Technology and Space (; abbreviated BMFTR) is a Cabinet of Germany, cabinet-level ministry of Germany. It is headquartered in Bonn, with an office in Berlin. The Ministry provides funding for research projects an ...

granted permission to build the facility on 5 June 2007 at a cost of €850 million, under the provision that it should be financed as a European project. The European XFEL

GmbH (; ) is a type of Juridical person, legal entity in German-speaking countries. It is equivalent to a (Sàrl) in the Romandy, French-speaking region of Switzerland and to a (Sagl) in the Ticino, Italian-speaking region of Switzerland. It is a ...

that built and operates the facility was founded in 2009. Civil construction of the facility began on 8 January 2009. Construction of the tunnels was completed in summer 2012, and all underground construction was completed the following year.European XFEL news
"European XFEL underground construction completed"
/ref> The first beams were accelerated in April 2017, and the first X-ray beams were produced in May 2017. XFEL was inaugurated in September 2017. The overall cost for the construction and commissioning of the facility is estimated at €1.22 billion (price levels of 2005).

References

External links

European XFEL website
*
Interactive Map

{{authority control Buildings and structures in Altona, Hamburg Buildings and structures in Pinneberg (district) Free-electron lasers International research institutes Physics in Germany Research institutes in Germany Research lasers Science and technology in Europe X-ray instrumentation