Neutron Dark-Field Tomography

We report how a grating interferometer yields neutron dark-field scatter images for tomographic investigations. The image contrast is based on ultrasmall-angle scattering. It provides otherwise inaccessible spatially resolved information about the distribution of micrometer and submicrometer sized structural formations. Three complementary sets of tomographic data corresponding to attenuation, differential phase, and small-angle scattering can be obtained from one measurement. The method is compatible with conventional imaging and provides significantly higher efficiency than existing techniques.

Figure 1

Grating interferometer. (a) Setup with three gratings, sample, and detector system. (b) The interference pattern induced by grating G1 smeared due to scattering in the sample.

Figure 2

Radiographic images: (a) attenuation, (b) differential phase (refraction), and (c) ultrasmall-angle scattering (dark-field image). (d) Attenuation parameter $a_0$ (offset), differential phase parameter $b_1$ (interferometer phase shift), and dark-field parameter basis $a_1$ (amplitude). (e) Line profiles corresponding to lines in (a–c).

Figure 3

Neutron dark-field tomography. (a) Reconstructed cross section from dark-field data of an Al matrix. (b) Representation of a detail of the volumetric reconstruction from dark-field data.

Figure 4

Detail of tomographic reconstruction. (a) Phase contrast. (b) Dark-field contrast. (c) Isolated three-dimensional representation of the sediments found in the dark-field data.