Instruments at Large Scale Facilities

The BIFROST spectrometer at ESS

Through the efforts of lead instrument scientist Rasmus Toft-Petersen and Lead Engineer Liam Whitelegg DTU Physics is leading the construction of the BIFROST spectrometer at the European Spallation Source (ESS) in Lund, Sweden. The construction project runs from 2016 to 2022. BIFROST is expected to enter the hot commissioning phase in the summer of 2022 and to be ready for external users at the start of the ESS user program in 2023. The BIFROST construction project is a multi-partner collaboration between

  • DTU Physics
  • The University of Copenhagen (Niels Bohr Institute), Denmark
  • The Paul Scherrer Institute (PSI), Switzerland,
  • Laboratoire Léon Brillouin (LLB), France
  • The Institute of Energy Technology (IFE), Norway.

In addition, the project benefits from input from EPFL Lausanne.

What is BIFROST?

BIFROST is an innovative indirect time-of-flight spectrometer with multi-energy analysis.

The instrument is capable of using the entire long pulse of ESS, guaranteeing a flux of neutrons incident on the sample which can be very large in the highest flux operational mode of the instrument (Up to 1010 neutrons per second per cm2 over a band-width of 1.7 Å) while maintaining good and flexible incident energy resolution.

On the secondary spectrometer side, BIFROST, neutrons of 5-6 different energies will be energy-analyzed simultaneously (exploiting the favorable transmission through the graphite analyzer crystals) over a broad range of (horizontal) scattering angles.

The combination of very large incident flux and the ability to probe the sample scattering function S(Q,ω) efficiently is expected to allow BIFROST to out-perform present world-leading instruments by a factor of 10.

Figure: The BIFROST spectrometer at ESS.

The science case of BIFROST

The science case of BFIROST is primarily centered on problems related to magnetism and quantum materials. Examples include strongly correlated electron materials e.g. high-temperature superconductors, quantum magnets, multiferroics etc. The very large flux of BIFROST will also enable novel geoscience and bioscience.


Rasmus Toft-Petersen
DTU Physics
+45 45 25 32 09


Liam Whitelegg
Lead instrument engineer
DTU Physics


Finn B. Saxild
Research Technician
DTU Physics
+45 46 77 47 57


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