We model the effect of ground movement, based on empirical experience, on the transport properties of long neutron guides by ray-tracing simulations. For a simple model, our results reproduce the large losses found by an earlier study, while for a more realistic engineering model of guide mounting, we find the losses to be significantly smaller. A detailed study of the guide for the cold neutron spectrometer BIFROST at the European Spallation Source shows that a realistic loss value is 7.0(5)% for wavelengths of 2.3–4.0 Å, the typical operational wavelength range of the instrument. This amount of loss does not call for mitigation by overillumination as suggested in the previous work. Our work serves to quantify the robustness of the transport properties of long neutron guides, in construction or planning at neutron facilities worldwide.

• Received 27 May 2020
• Accepted 14 September 2020

DOI:https://doi.org/10.1103/PhysRevAccelBeams.23.103501

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society