High energy transmission annular beam X-ray diffraction.

We demonstrate material phase retrieval by linearly translating extended polycrystalline samples along the symmetry axis of an annular beam of high-energy X-rays. A series of pseudo-monochromatic diffraction images are recorded from the dark region encompassed by the beam. We measure Bragg maxima from different annular gauge volumes in the form of bright spots in the X-ray diffraction intensity. We present the experiment data from three materials with different crystallographic structural properties i.e. near ideal, large grain size and preferred orientation. This technique shows great promise for analytical inspection tasks requiring highly penetrating radiation such as security screening, medicine and non-destructive testing.

Validation study of a ray-tracing simulator for focal construct geometry.

We present the results of a computer modelling package designed to simulate X-ray diffraction imaging employing focal construct geometry. The paths of coherently diffracted X-rays are modelled by ray-tracing. The results of the study show good agreement between simulated and measured data obtained in the laboratory. The validation of the modelling package permits the rapid optimisation and prototyping of focal construct technology, which has wide applicability in security X-ray imaging.