Advances in Nuclear Data and Software Development for the HighNESS Project.

The European Spallation Source, which is under construction in Lund, Sweden, aims to be the world's brightest source of neutrons. During the first phase of construction, users will have access to a suite of 15 instruments, which will produce neutrons through a butterfly-shaped moderator system located above the spallation target. The HighNESS project, funded by the European Union Horizon 2020 program, has the goal of providing a new design for the second moderator, which will be situated below the spallation target and will be the most intense neutron source in the world. The new moderator will provide a higher intensity of neutrons in the cold, very cold, and ultracold energy regions, which will advance research in several areas of condensed matter and offer unique opportunities in fundamental physics. Work Package 2 of the HighNESS project is focused on supporting the design of the second moderator by providing nuclear data support for neutronics calculations and improving the accompanying physics software. This paper showcases recent advancements in NJOY + NCrystal, a tool for creating thermal neutron scattering–evaluated nuclear data files and continued work on nanodiamonds as advanced neutron reflectors. [ABSTRACT FROM AUTHOR]