Figure 1
Experimental ToF 3DND setup. The sample is illuminated by a time-of-flight neutron beam and an imaging detector is installed in transmission geometry. When, at a sample rotation angle ω, a grain satisfies the Bragg condition, a region of missing intensity (extinction spot) is visible in transmission. The diffracted beam forms a bright diffraction spot. In the plot, the laboratory, sample and detector reference systems are denoted by (X l , Y l , Z l ), (X s , Y s , Z s ) and (Y d , Z d ) respectively. While the 3D shape of the grains can be reconstructed using extinction spots only, uniquely determining their orientation requires considering also the location of the diffraction spots. In real space, this position is determined by the direction of the diffraction vector L Lab , which connects the centre of mass (CM) of the grain, located by x l , with the centre of mass of the related diffraction spot. The relationship between x l and the position, in the laboratory reference system, of the centre of mass x d of the diffraction spot on the detector plane is x d = x l + L Lab · s.
