Inelastic neutron scattering is instrumental in making key discoveries in a broad range of materials, such as superconductors, multiferroic materials and quantum magnets. However, the applicability of the technique is limited by inherently weak signals, leaving parametric studies as a function of sample environment parameters relatively inaccessible.
BIFROST, currently under construction at the European Spallation Source (ESS), aims to drastically shift those limits of feasibility by combining a multiplexing crystal analyzer backend with an indirect geometry time-of-flight front end. Due to the peak brilliance and long pulse of the ESS source, the primary spectrometer enables an unprecedented polychromatic sample flux exceeding 10^10 n/s/cm2 at 5 MW accelerator power, with a primary spectrometer resolution ΔEi/Ei of 4 %, common in cold neutron spectroscopy. The multiplexing backend consists of 9 Q-channels with continuous angular sensitivity, each containing 5 fixed analyzers probing neutron energies below 5.0 meV. The analyser backend utilize position sensitive detectors to significantly improve energy resolution as compared to a normal triple-axis backend. By shaping the source pulse, an energy resolution well below 0.1 meV is obtainable even far from the elastic line while retaining a respectable flux on the sample.
Instrument construction is making significant progress, with major components installed, and the instrument slated for completion by the end of 2023.