Photo: Bax Lindhardt

Strong Danish contributions to ESS in Lund

Friday 17 Aug 18


Rasmus Toft-Petersen
Senior Researcher
DTU Physics
+45 45 25 32 93


Niels Bech Christensen
Senior Scientist
DTU Physics
+45 45 25 32 06


Ken Andersen, Head of Neutron Instruments Division, ESS.



European Spallation Source (ESS) is more than 100 times as powerful as similar facilities currently in operation. ESS is the largest Danish research project since the time of Tycho Brahe.

ESS will accelerate protons in a 500-metre-long long tunnel, after which they will hit a tungsten target and scatter neutrons away from the tungsten nuclei. The process is known as spallation. Neutrons are guided to the instruments where they can penetrate materials and show their hidden structures, right down to the location of individual atoms.

ESS in Lund has a total construction budget of EUR 1,843 billion, of which Denmark contributes about 12.5 per cent.

One of Europe's largest research facilities, the European Spallation Source (ESS), is currently taking shape in a field outside Lund in Sweden. Denmark is heavily involved in the project.

ESS will be the world’s most advanced neutron source. Like a huge microscope, it allows researchers and companies not only to examine the surfaces of materials, but also to visualize their structure down to the atomic and molecular level. ESS will therefore play a major role in the understanding of materials in diverse areas such as life science, health, energy, and information technology.

The joint hosting by Denmark and Sweden means that while the actual neutron source will be built in Lund, the associated data processing centre will be located in Copenhagen. However, Denmark is also making significant contributions to the new research complex. For example, two of the first ESS instruments have been developed and built by Danish researchers.

One of the first instruments to be made available to researchers at the start of the ESS research programme in 2023 is ‘Bifrost’. The team developing Bifrost is headed by Rasmus Toft-Petersen, a researcher from DTU physics.

“Bifrost will allow researchers to measure crystal lattice and magnetic oscillations. This has traditionally been done using time-of-flight or three-axes spectrometers. Bifrost combines the best elements from these types of instruments in a completely new way and on a large scale,” he says.

“We have spent the last few years designing and doing calculations on Bifrost—both the instrument as a whole and its components. Everything must be properly dimensioned to leverage the large volume of neutrons that will be emitted from the core of ESS to the instruments in powerful pulses. This work is almost finished, and we are now in the process of purchasing the various components to build Bifrost.”

About 8,000 different components are required. When completed, the instrument will have a 160-metre-long neutron guide—the ‘pipe’ that guides neutrons from the spallation source at ESS to the test station. From the test station, the neutrons will be scattered and detected in a six-tonne tank, which rotates 30 degrees back and forth.

Basic research
Bifrost will be used, in particular, for basic research in the fields of magnetism and quantum materials.

The experiments will focus on gaining a better understanding of how magnetic materials behave under the influence of pressure or external magnetic fields. Complex magnetic materials can be the key to increasing the efficiency of electronics used in the IT sector, for example by being able to store larger volumes of information in less space and with lower power consumption.

Bifrost will also be able to contribute new knowledge in the energy field, where a basic scientific understanding of high-temperature superconductors is an important objective, which would open up promising technological possibilities.

“Bifrost has the potential to provide us with unique information which is not available elsewhere in the world. Researchers will come here having developed new materials in their laboratories, for example materials with interesting potential in the form of magnetic or superconducting properties,” explains Senior Scientist Niels Bech Christensen from DTU Physics, who has the overall responsibility for Bifrost.

Bifrost project participants

DTU is responsible for the overall management of the project.

Other project participants are the University of Copenhagen (UCPH), EPFL Lausanne and the Paul Scherrer Institute in Switzerland, Laboratoire Leon Brillouin in France, and Institute for Energiteknikk in Norway.

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