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 $2.3-4.0$, 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.

中文翻译：

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地面运动对欧洲散裂源现实指导模型的影响

我们基于经验，通过射线追踪模拟对地面运动对长中子导管传输特性的影响进行建模。对于简单的模型，我们的结果重现了较早研究发现的巨大损失，而对于更现实的导轨安装工程模型，我们发现损失要小得多。在欧洲散裂源处对冷中子光谱仪BIFROST的指南进行的详细研究表明，对于波长为的波长，实际损耗值为7.0（5）％。$2.3-4.0$，仪器的典型工作波长范围。如先前工作中所建议的那样，这种损失量并不要求通过过度照明来减轻。我们的工作旨在量化在全球中子设施的建设或规划中长中子导管的传输特性的鲁棒性。