Neutron scattering: A subsurface application review

Geomaterials and filling fluids properties that are pertinent to a geologic porous media can be characterized using a range of methods, such as nuclear magnetic resonance, X-rays, infrared spectroscopy, and neutron scattering (NS). In this context, NS features as an important tool elucidate key properties of a porous medium, which has recently gained significant attention. Key rock properties that can be measured by NS include: rock texture (i.e. crystallographic preferred orientation), mechanical properties (i.e. stress and strain) as well as porous medium properties (pore porosity, pore size and connectivity). In addition, NS imaging can help elucidate the phase behaviour of confined reservoir fluids in rock matrix under prevailing pressures and temperatures. Thus, a precise characterization of these properties (amongst other multiphase flow attributes) is critical for several applications in varied fields such as hydrocarbon reservoirs, geothermal systems, crystallography, geomechanics and geochemistry. Low neutron attenuation by most substances (deep sample penetration) and strong neutron attenuation by hydrogen are essential features of neutrons that allow NS to collect high-quality data across a wide variety of subsurface conditions. These features enable NS to be ideally suited to some applications as compared to other techniques such as X-rays and magnetic resonance imaging (MRI). For example, X-rays may not have sufficient resolutions for examining nanopore structures and confined fluids. Contrastingly, MRI is limited by the visualization of a range of pore sizes. However, NS can capture angstrom-to-micron-scale information of atomic to meso-to-macro-scale structures of rocks and fluids (i.e. hydrogen-rich fluids) inside a porous medium. These insights are vital for predictive reservoir models, where meaningful reservoir-scale (hectometre-scale) predictions can be performed. However, when compared to X-rays, neutrons have weak sources and/or low signals; therefore, experimental time can be quite long and samples need to be relatively large. Other limitations of NS (some may be also true of other techniques) include problems like accessing neutron sources (e.g. complicated nuclear processes for neutron production and small number of available instruments when compared to X-rays), high costs, and the strong absorption of neutron signals by some elements [e.g. cadmium (Cd), boron (B), and gadolinium (Gd)]. Despite the potential of NS, a review that considers key NS subsurface applications, limitations, and outlooks is currently lacking. Thus, in this review, we describe the basic concepts, experiments, methods, requirements, restrictions, and applications of NS for rock and fluid characterization. This study finds that despite its overall challenges, NS is a promising technique for characterizing subsurface rock and fluid systems, opening diverse avenues for future technological and scientific research within this area

Leave no trace: A non-destructive correlative approach providing new insights into impactites and meteorites

Impact cratering is today recognized as a fundamental geological process on all rocky bodies in the solar system. On Earth, however, processes such as plate tectonics and erosion have eradicated most craters from the geological record, or they may be buried under sediments, oceans, and vegetation. The formation of a hypervelocity impact crater involves extreme pressures and temperatures that induce permanent changes in the target rocks, so-called shock-metamorphic effects, which can be used to identify and confirm impact structures. The research in this thesis focuses on the impact cratering process, both during the formation, and post-impact. A number of terrestrial impactites and meteorites were analyzed using a multi-modal approach, including correlative non-destructive neutron and X-ray imaging, and detailed 2D analysis using scanning electron microscopy and electron backscatter diffraction. The material encompasses (1) impactites from the Mien impact structure, (2) a sample of the Martian Miller Range (MIL) 03346 meteorite, (3) a Chicxulub drill core sample, (4) a sample of Libyan Desert Glass, and (5) a sample of impact melt rock from the Luizi impact structure. The first study investigated shock deformation in zircon grains from the Mien impact structure in Sweden, using electron backscatter diffraction (EBSD). The results show that several of these grains contain evidence of the former presence of a high-pressure phase that is only known from impact structures. These grains would be suitable candidates for refining the age of the impact event. In paper II, combined NCT and XCT were employed to investigate the three-dimensional distribution of hydrogen-rich material in MIL 03346, by utilizing the neutrons’ sensitivity to hydrogen. The results revealed that the hydrogen-rich material occurs in localized clusters, with limited interconnectivity between clusters. This suggests that the fluid source could be small patches of sub-surface ice and that the alteration event likely was short-lived, meaning that the source terrain of this sample was likely not habitable. In Paper III we combined XCT and NCT to test if these methods can be used to locate projectile material in impactites. After careful investigations of the 3D images, an iron-nickel silicide spherule could be pin-pointed in the Libyan Desert glass. The sample was then polished for detailed analysis using scanning electron microscopy. Overall, the non-destructive nature of XCT and NCT makes these methods highly relevant for studying rare samples, such as meteorites and returned samples

2nd International Workshop on Advanced Techniques for Actinide Spectroscopy (ATAS 2014) Abstract Book

In 2012, The Institute of Resource Ecology at the Helmholtz-Zentrum Dresden Rossendorf organized the first international workshop of Advanced Techniques in Actinide Spectroscopy (ATAS). A very positive feedback and the wish for a continuation of the workshop were communicated from several participants to the scientific committee during the workshop and beyond. Today, the ATAS workshop has been obviously established as an international forum for the exchange of progress and new experiences on advanced spectroscopic techniques for international actinide and lanthanide research. In comparison to already established workshops and conferences on the field of radioecology, one main focus of ATAS is to generate synergistic effects and to improve the scientific discussion between spectroscopic experimentalists and theoreticians. The exchange of ideas in particular between experimental and theoretical applications in spectroscopy and the presentation of new analytical techniques are of special interest for many research institutions working on the improvement of transport models of toxic elements in the environment and the food chain as well as on reprocessing technologies of nuclear and non-nuclear waste. Spectroscopic studies in combination with theoretical modelling comprise the exploration of molecular mechanisms of complexation processes in aqueous or organic phases and of sorption reactions of the contaminants on mineral surfaces to obtain better process understanding on a molecular level. As a consequence, predictions of contaminant’s migration behaviour will become more reliable and precise. This can improve the monitoring and removal of hazardous elements from the environment and hence, will assist strategies for remediation technologies and risk assessment. Particular emphasis is placed on the results of the first inter-laboratory Round-Robin test on actinide spectroscopy (RRT). The main goal of RRT is the comprehensive molecular analysis of the actinide complex system U(VI)/acetate in aqueous solution independently investigated by different spectroscopic and quantum chemical methods applied by leading laboratories in geochemical research. Conformities as well as sources of discrepancies between the results of the different methods are to be evaluated, illuminating the potentials and limitations of cou-pling different spectroscopic and theoretical ap-proaches as tools for the comprehensive study of actinide molecule complexes. The test is understood to stimulate scientific discussions, but not as a competitive exercise between the labs of the community. Hopefully, the second ATAS workshop will continue to bundle and strengthen respective research activities and ideally act as a nucleus for an international network, closely collaborating with international partners. I am confident that the workshop will deliver many exciting ideas, promote scientific discussions, stimulate new developments and collaborations and in such a way be prosperous. This workshop would not take place without the kind support of the HZDR administration which is gratefully acknowledged. Finally, the or-ganizers cordially thank all public and private sponsors for generous funding which makes this meeting come true for scientists working on the heavy metal research field

Synchrotron and Neutron Tomography of Paleontological Objects on the Facilities of the Kurchatov Institute

The most important results of tomographic studies of paleontological objects on the facilities of the National Research Centre “Kurchatov Institute” are described. It is shown that the use of the synchrotron and neutron tomography makes it possible to obtain new information on the structure of fossil animals, which is of fundamental importance for taxonomy and morphological analysis of extinct fauna