neutron grating interferometry (nGi) is a unique technique allowing to probe magnetic and nuclear properties of materials not accessible in standard neutron imaging. the signal-to-noise ratio of an nGI setup is strongly dependent on the achievable visibility. Hence, for analysis of weak signals or short measurement times a high visibility is desired. We developed a new talbot-Lau interferometer using the third Talbot order with an unprecedented visibility (0.74) over a large field of view. Using the third talbot order and the resulting decreased asymmetry allows to access a wide correlation length range. Moreover, we have used a novel technique for the production of the absorption gratings which provides nearly binary gratings even for thermal neutrons. the performance of the new interferometer is demonstrated by visualizing the local magnetic domain wall density in electrical steel sheets when influenced by residual stress induced by embossing. We demonstrate that it is possible to affect the density of the magnetic domain walls by embossing and therefore to engineer the guiding of magnetic fields in electrical steel sheets. The excellent performance of our new setup will also facilitate future studies of dynamic effects in electric steels and other systems. Neutron radiography is a method allowing for non-destructive analysis of the inner structure of an object 1. Because the neutron cross-sections show no systematic dependence on the atomic number, both light and heavy elements can be visualized. Moreover, the contrast between different materials can be varied by using isotopes. Therefore, neutron imaging has been established to be a very efficient technique in materials science, research in cultural heritage, archaeology, and engineering, where imaging with X-rays fails to produce sufficient contrast. Neutron imaging is, however, limited by the coarse spatial resolution imposed by the limitations in neutron flux and the spatial resolution of the neutron detectors. Currently, the achieved spatial resolution is in the low single μm range 2-7. Paths towards resolving structures with higher resolution (e.g. water transport in fuel cells) are, for example, improving the detector resolution 3-6 or in some cases using neutron grating interferometry (nGI) 8,9 as a spatially resolved ultra-small-angle scattering technique. nGI simultaneously gathers spatially resolved information about the transmission-(TI), the differential phase contrast-(DPCI) and the scattering/dark-field (DFI) of a sample. Most notably, the contrast provided by the DFI 10,11 is generated by ultra-small-angle neutron scattering (USANS) off structures on a length scale similar to the correlation length of the interferometer setup, which is typically in the range 0.1 μm to 10 μm. Such structures are caused by variations of the nuclear or magnetic

No abstract

No abstract

No abstract

No abstract