Thermal neutron cross sections of aluminum and magnesium fluorides and quantum kinetic energy of fluorine

We provide the modeling and experimental validation of thermal neutron cross sections, including scattering and absorption contributions, of aluminum fluoride and magnesium fluoride, as well as MgF2-AlF3 and AlF3-LiF mixtures, in the neutron energy range between 0.6 meV and 1 keV. The neutron scattering properties have been investigated as a function of temperature, between 10 and 370 K, and sample microscopic structure, focusing in particular on differences between powder and sintered samples. Concurrent measurements of neutron transmission, neutron diffraction, neutron resonance capture analysis, and neutron Compton scattering provide a comprehensive picture of scattering and transport properties of these materials. We provide crystallographic information at the atomic scale, the effect of sintering on the grain size at the nanometer scale, the related occurrence of small angle scattering, and the impact of fluorine zero-point nuclear energy at different temperatures, requiring the use of an effective temperature to model its scattering within the impulse approximation. Finally, combining this self-consistent experimental information, we discuss the application of the uncertainty principle to the fluorine single-particle potential. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) license (https://creativecommons.org/licenses/by-nc-nd/4.0/).