# Angströmquelle Karlsruhe

ANKA (abbreviation for „Angströmquelle Karlsruhe“) is a synchrotron light source facility at the Karlsruhe Institute of Technology (KIT) in Karlsruhe, Germany. The KIT runs ANKA as a national synchrotron light source and as a large scale user facility for the international science community. Being a large scale machine of the performance category LK II of the Helmholtz Association (Helmholtz Association of German Research Centres), ANKA is part of a national and European infrastructure offering research services to scientific and commercial users for their purposes in research and development. The facility was opened to external users in 2003.

## History

In 1997, the decision was formed to realize the project of building the large scale facility ANKA on the premises of the former Research Center Karlsruhe. By the end of 1998, the outer structure of ANKA was erected, and already in 1999, the first electrons were inducted into the storage ring. After a few more years of machine and laboratory development, in March 2003 ANKA opened its doors for users from the science community and industry, initially featuring seven beamlines: six analytical beamlines and one for the generation of microstructures using X-ray lithography. Since then further improvements and extensions were continuously developed and implemented: Currently 15 beamlines are in operation, three more are in the process of installation. The machine itself saw the implementation of several updated generations of its insertion devices (undulators and wigglers) that were in part developed at ANKA. Moreover, a fully developed infrastructure supports users at ANKA, as for example fully equipped user apartments on the premises of the KIT Campus North can be booked by external ANKA users.

## Technical Details

ANKA features a storage ring with a circumference of 110.4 m (120.7 yards) that stores electrons at the energy of 2.5 GeV. For this purpose, electrons (90 keV) are generated by a triode and preaccelerated to 500 MeV via a “Racetrack Microtron” (53 MeV) and a booster. The actual working energy is finally reached in the storage ring, where the electrons are now spinning at almost the speed of light. The storage ring contains an ultra-high vacuum of 10$^{−9}$ mbar. The synchrotron light is thereby generated by the constant deflection of 16 magnets that keep the electrons focused in the center of the tube. In addition to that, wigglers and undulators – specialized magnet configurations with alternating straight and reverse polarity – are used to deflect the electrons into a sinus-curve-like course on which they emit synchrotron radiation. A special feature of the ANKA synchrotron configuration is the super conducting SCU15 undulator that was – as its predecessor SCU14 – co-developed at the ANKA facility. This new undulator does not only generate synchrotron light of enhanced brilliance, but also a much more variable spectrum of radiation easily adjustable to the respective research requirements.

## ANKA beamlines and their applications
### Imaging methods
#### IMAGE

    Use of X-rays for imaging procedures in 2D- and 3D-fields, static as well as dynamic – in the state of installation

#### MPI-MF

    Conducted by the Max-Planck-Institute for Intelligent Systems, Specialized on in situ analyses of interfaces and thin films

#### NANO

    High definition in-situ X-ray diffraction – in the final phase of installation

#### PDIFF

    Analysis using the Debye-Scherrer-Powder diffraction (examination and identification of crystalline substances in powdered samples

#### SCD

    Analysis of X-ray diffraction on single crystals

#### TOPO-TOMO

    Topography, microradiology and microtomography using polychromatic light and X-rays

### Spectroscopy
#### FLUO

    X-ray fluorescence spectroscopy, non-destructive qualitative and quantitative identification of the elemental composition of a sample

#### INE

    Installed and conducted by the KIT Institute for Nuclear Waste Disposal for the sake of actinide-research

#### IR1

    Infrared spectroscopy and infrared ellipsometry including terahertz radiation

#### IR2

    Infrared spectroscopy and infrared microscopy including terahertz radiation

#### SUL-X

    Absorption, fluorescence- and diffraction analysis as part of the synchrotron environmental laboratory

#### UV-CD12

    Conducted by the KIT Institute for Biological Interfaces, UV-circular dichroism-spectroscopy (structural analysis of biological substances)

#### WERA

    Soft X-ray analysis conducted by the KIT Institute for Solid-State Physics

#### XAS

    X-ray absorption spectroscopy, XANES (chemical composition of a sample) and EXAFS (Number, distance and type of neighboring atom (also in non-crystalline form)

### Microfabrication
#### LIGA I, II, III

    Deep X-ray lithography according to the LIGA-procedure developed at the KIT. The three beamlines differ regarding the level of available energy

## Access for scientific users

Besides the scientists at ANKA and IPS that contribute to the development of the synchrotron and its components, external users in particular have the opportunity to use the radiation generated at ANKA for their own research projects. Users of the international science community are coordinated by ANKA's user office. Twice a year, proposals for beamtime at ANKA are collected via an online application procedure. The actual beamtime is then allocated by an international scientific committee that evaluates the submitted proposals. On the premises of KIT Campus North a guest house grants the accommodation of external users for the time of their project at ANKA. More information on the allocation of beamtime can be found on the web pages of the user office.