Study of cold neutron extraction efficiency of the bi-spectral switch optics for the engineering ToF-diffractometer BEER at ESS.

The proposed study is focused on the characterization of the neutron optical element called “bi-spectral switch” for the engineering diffraction beamline BEER under construction at the ESS. BEER enables preferentially in-situ and in-operando neutron ToF-diffraction techniques for phase-, residual stress- and texture analysis on structural, technological relevant, engineering materials of a high symmetric crystalline structure. The bi-spectral switch is expected to increase the feed-in ratio of cold neutron fraction from the bi-spectral moderator of the ESS-source into the BEER-beamline. The characterization is targeting on the cost-benefit comparison of the bi-spectral switch in the application case. The costs here are the absorbed thermal neutron fraction when the device is placed in the beam to raise the extraction rate of the cold neutrons. The proposed characterization shall elucidate the degree of congruence between simulated and measured performance and enable a successful and time-critical installation of the device in the access-restricted bunker area of the ESS before first quarter of 2025.