Conveners
Source Materials
- Jeroen Plomp (Delft University of Technology)
- Paul Zakalek (Forschungszentrum Jülich GmbH)
We present the development of a model to describe the interactions of neutrons in normal and superfluid He-4 at temperatures below 2.17 K. The model was constructed based on the separation of the single-phonon and multi-phonon excitations at low temperatures. Below around 3.4 Å-1, the single-phonon excitations are described exactly by the dispersion relation, while the multi-phonon excitations...
Cold neutron moderator design evolution has led to two main solutions. Flux-hungry instruments using large samples and limited angular resolution require a large bright surface and are better served by the LD2 moderators. Brilliance-hungry instruments using small samples and requiring a fine angular resolution are best served by L-pH2 moderators with sizes exactly matching the required....
Clathrate hydrates [1] are water-based solids with large unit cells which show promise as moderators for use in the development of new and more intense sources of very cold neutrons (VCN). Such sources have the potential to enhance existing neutron scattering techniques as well as to increase the reach of particle physics experiments employing beams of slow neutrons
The moderation potential...
The way to identify and characterize potentially interesting neutron-moderating materials is to measure their neutronic properties: vibrational density of states (VDoS) and total cross-section. The idea behind the VDoS measurements is to look for low energy vibrational modes that can enable efficient moderation of neutrons in the so-called cold energy region.
TOSCA instrument [1] at the...
A major milestone in cold neutron moderator developments has been the invention of low-dimensional geometries [1], such as the butterfly moderator of ESS. Monte-Carlo simulations have shown that if para-hydrogen is used as moderator material, these novel moderators can increase significantly the brightness, desired by most types of neutron instruments. Various designs were extensively studied...
