Extracting micro-structural and rotational information in granular materials such as: sand-piles, coffee beans, planetary rings, powders etc. is a challenging task. The limits are in general the opacity of the sample and the degree of complexity seen in granular systems. Structure and dynamics in granular matter is not only of fundamental importance, where the sandpile has become the physicist’s trendy “out of equilibrium model”, but also of great practical consequence in commercially related applications. Therefore more experiments and new techniques are needed and much sought after.
Neutron depolarisation (PANDA) has been proven successful for measuring particle rotations in powders directly and Spin-Echo Small Angle Neutron scattering (SESANS) is used to measure structure and ordering (pair-correlation function) in granular packings. Common for both techniques is the use of the high penetrability of neutrons combined with neutron-spin manipulation methods.