Characterization of oriented microstructures through anisotropic small-angle scattering by 2D neutron dark-field imaging

Jacopo Valsecchi,Chiara Carminati,Markus Strobl,Anders Kaestner,Matias Kagias,Ralph Patrick Harti,Zhentian Wang,Pavel Trtik,Konstantins Jefimovs,Christian Grünzweig

doi:10.1038/s42005-020-0308-4

Abstract

Within neutron imaging, different methods have been developed with the aim to go beyond the conventional contrast modalities, such as grating interferometry. Existing grating interferometers are sensitive to scattering in a single direction only, and thus investigations of anisotropic scattering structures imply the need for a circular scan of either the sample or the gratings. Here we propose an approach that allows assessment of anisotropic scattering in a single acquisition mode and to broaden the range of the investigation with respect to the probed correlation lengths. This is achieved by a far-field grating interferometer with a tailored 2D-design. The combination of a directional neutron dark-field imaging approach with a scan of the sample to detector distance yields to the characterization of the local 2D real-space correlation functions of a strongly oriented sample analogous to conventional small-angle scattering. Our results usher in quantitative and spatially resolved investigations of anisotropic and strongly oriented systems beyond current capabilities.

Highlights

Within neutron imaging, different methods have been developed with the aim to go beyond the conventional contrast modalities, such as grating interferometry
In order to overcome this limitation in directional sensitivity, here we demonstrate a broadband, single-shot imaging approach with 2D dark-field small-angle scattering (SAS) resolution based on a neutron far-field interferometer characterized by a grating design consisting of small pitch circular gratings arranged into a square array
The single-shot approach in contrast to the existing methods does not require any rotation of the sample nor the gratings during acquisition compared to existing methods

Summary

Introduction

Different methods have been developed with the aim to go beyond the conventional contrast modalities, such as grating interferometry. We propose an approach that allows assessment of anisotropic scattering in a single acquisition mode and to broaden the range of the investigation with respect to the probed correlation lengths This is achieved by a far-field grating interferometer with a tailored 2D-design. Most of the investigations carried out with nGI have mainly focused on the small-angle scattering information provided by the DFI20 This contrast modality provides information on the microstructures of the sample on (sub)micrometer length scales, beyond the resolution capability of conventional neutron imaging[21,22,23,24,25]. Different approaches including new grating designs, such as checkerboard and speckle patterns paved the way for further developments[52,53,54,55,56,57,58,59]

Methods

Results

Conclusion