Naver Estrid Buhl, Yetik Okan, Ott Noémie, Busi Matteo, Trtik Pavel, Theil Kuhn Luise, Strobl Markus
Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark.
Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen, Switzerland.
Sci Rep. 2024 Oct 16;14(1):24218. doi: 10.1038/s41598-024-75264-w.
Neutron imaging has gained significant importance as a material characterisation technique and is particularly useful to visualise hydrogenous materials in objects opaque to other radiations. Fields of application include investigations of hydrogen in metals as well as metal corrosion, thanks to the fact that neutrons can penetrate metals better than e.g. X-rays and are highly sensitive to hydrogen. However, at interfaces refraction effects sometimes obscure the attenuation image, which is used for hydrogen quantification. Refraction, a differential phase effect, diverts the neutron beam away from the interface in the image leading to intensity gain and intensity loss regions, which are superimposed to the attenuation image, thus obscuring the interface region and hindering quantitative analyses of e.g. hydrogen content in the vicinity of the interface. For corresponding effects in X-ray imaging, a phase filter approach was developed and is generally based on transport-of-intensity considerations. Here, we compare such an approach, that has been adapted to neutrons, with another simulation-based assessment using the ray-tracing software McStas. The latter appears superior and promising for future extensions which enable fitting forward models via simulations in order to separate phase and attenuation effects and thus pave the way for overcoming quantitative limitations at refracting interfaces.
中子成像作为一种材料表征技术已变得极为重要，尤其有助于在对其他辐射不透明的物体中可视化含氢材料。其应用领域包括对金属中的氢以及金属腐蚀的研究，这得益于中子比例如X射线能更好地穿透金属且对氢高度敏感这一事实。然而，在界面处，折射效应有时会使用于氢定量分析的衰减图像变得模糊。折射是一种微分相位效应，它会使图像中的中子束偏离界面，导致强度增加和强度损失区域，这些区域叠加在衰减图像上，从而模糊了界面区域并阻碍了对例如界面附近氢含量的定量分析。对于X射线成像中的相应效应，人们开发了一种相位滤波器方法，该方法通常基于强度传输的考虑。在此，我们将这种已适用于中子的方法与另一种使用射线追踪软件McStas的基于模拟的评估方法进行比较。后者似乎更具优势，并且对于未来的扩展很有前景，这些扩展能够通过模拟拟合正向模型，以便分离相位和衰减效应，从而为克服折射界面处的定量限制铺平道路。
