Investigation of a Monturaqui Impactite by Means of Bi-Modal X-ray and Neutron Tomography

Abstract

X-ray and neutron tomography are applied as a bi-modal approach for the 3D characterisation of a Monturaqui impactite formed by shock metamorphism during the impact of an iron meteorite with the target rocks in the Monturaqui crater (Chile). The particular impactite exhibits structural heterogeneities on many length scales: its composition is dominated by silicate-based glassy and crystalline materials with voids and Fe/Ni-metal and oxihydroxides particles generally smaller than 1 mm in diameter. The non-destructive investigation allowed us to apply a novel bi-modal imaging approach that provides a more detailed and quantitative understanding of the structural and chemical composition compared to standard single mode imaging methods, as X-ray and neutron interaction with matter results in different attenuation coefficients with a non-linear relation. The X-ray and neutron data sets have been registered, and used for material segmentation, porosity and metallic content characterization. The bimodal data enabled the segmentation of a large number of different materials, their morphology as well as distribution in the specimen including the quantification of volume fractions. The 3D data revealed an evaporite type of material in the impactite not noticed in previous studies. The present study is exemplary in demonstrating the potential for non-destructive characterisation of key features of complex multi-phase objects such as impactites.

The XTRA Option at the NEUTRA Facility—More Than 10 Years of Bi-Modal Neutron and X-ray Imaging at PSI

“…In these cases, the registration is mostly done using commercial software such as VG Studio MAX. This enables, in many cases, the identification of specific material phases due to their complementary contrast behavior and specific combinations of neutron and X-ray attenuation (Figure 4) [12,13]. Specifically, in [12] the registration was done using a combination of commercially available and custom-developed Monte Carlo-based algorithms.…”

“…(i) Visualization based on color coding using the measured intensity of the modalities directly based on different color models and opacity: a. Let each contrast modality control a color channel in an RGB image [13] (Figure 4). The remaining color channel is usually the average of the two modalities; b.…”

The Bimodal Neutron And Photon Imaging Driven By A Single Electron Linear Accelerator

“…This bimodal imaging approach was rst implemented by E.H. Lehmann in 2006 by two separate facilities for X-ray and neutron radiography 1 . Analogous facilities were later constructed by many institutes such as PSI, NIST, and ILL [9][10][11][12] . All the studies are conducted on large neutron sources (reactor or spallation neutron sources) with the aid of a 100 ~ 200 kV X-ray tube.…”

A structural insight into the Chelyabinsk meteorite: neutron diffraction, tomography and Raman spectroscopy study

“…The measurements of the chemical composition and spatial distribution of components of the Chelyabinsk meteorite could gain new insights into its origin [3,18,19]. Due to uniqueness of the meteoritic matter, an application of non-destructive testing methods provides particular advantages [18,20,21]. The conventional methods like the X-ray fluorescence analysis, scanning electron microscopy or X-ray diffraction have a significant limitation on the depth of penetration into the thickness of the studied samples.…”

“…In contrast, neutron diffraction and neutron tomography methods provide a non-destructive probe of structural organization of objects with high bulk penetration [22][23][24][25][26]. The fundamental difference in the nature of neutron interactions with matter compared to X-rays provides additional benefits including sensitivity to light elements, a notable difference in contrast between neighboring elements like nickel and iron [18,21,22]. All these features make neutron methods highly demanded tool with a growing range of applications in industry [25], archeology [26,27] and geophysics [28] including studies of meteorites [18,20,21].…”