Bachelor's defense: Amalie Falkenberg Davidsen

The Instrument Concept for KVASIR

At the European Spallation Source (ESS) a proposal round for new instruments to be built is pending, and the neutron scattering group at the Niels Bohr Institute (NBI) is co-proposing a quasi elastic backscattering instrument for hard condensed matter, with optimized energy and momentum transfer resolution. The concept is named KVASIR.
The instrument is proposed to have a constant Ef of 1.95 meV in order to optimize the energy resolution within the range of the scattering triangle, aiming at an energy resolution of the secondary spectrometer of 4 μeV. In order to optimize the energy resolution for the primary spectrometer, a flight path of 160mis suggested, making the primary flight path relatively long for the time of flight conversion of the energy. In addition to this, the secondary spectrometer will utilize modern methods to optimize the energy resolution. The secondary spectrometer is optimized, not only for energy resolution, but also for q-resolution, making the instrument ideal for hard condensed matter experiments. A q-resolution of 0.03 ˚A−1 is estimated. In order to test the instrument concept, the McStas package has been used to numerically simulate a 160mguide along with a secondary spectrometer. Both the primary and secondary spectrometer are optimized for energy and q-resolution. An energy resolution of 9 μeV along with a q-resolution of 0.03 ˚A−1 is simulated.
The long term goal of the project is to develop the simulated secondary spectrometer into a full digital twin, providing insight into the performance. KVASIR will make it possible to access regions in reciprocal space in hard condensed matter with yet unseen accuracy.