Time-series analysis of 2D diffraction patterns for Synchrotron rock physics

Overview

The interaction between deformation, fluid flow, chemical reactions, and heat flow in rocks constitutes a research frontier in the Earth Sciences. In addition to fundamental academic interest in this subject, there are many applied industrial problems, which require a sound understanding of this coupling. Examples include: the long-term sequestration of carbon dioxide in rocks, the energy-efficient processing of future-mineral resources, the design of unconventional geothermal-energy operations, and the prediction of earthquakes and volcanic eruptions.

The advisory team pioneered new methods for in-situ rock physics experiments monitored with Synchrotron radiation to investigate multi-physics processes in real time, from the scale of 0.1 nm to 1 cm. One of these breakthrough techniques is Synchrotron small- and wide-angle X-ray scattering (SAXS/WAXS). X-ray scattering at wide angles (WAXS) monitors processes at the scale of the crystal lattice and is thus used to track chemical reactions and phase transformations. Scattering at small angles (SAXS) reflects, in most instances, processes in cracks and pores from the scale of 1 nm to ca. 500 nm.

SAXS and WAXS signals are recorded as 2D intensity maps with highly sensitive detectors that count single photons. Image processing and mathematical model-fitting are required to convert these scattering patterns into quantitative information on chemical reactions, fluid flow, phase transformation, and pore formation.

In our experimental rock-physics set-up, hundreds to thousands of SAXS/WAXS maps are produced for each single experiment. Therefore, the development of unsupervised image-analysis and modelling approaches is needed to analyse and interpret our large time-series experiments.

Two categories of student projects are available:

• [A] Development and testing of new methods for automated analyses of time-series SAXS/WAXS datasets
• [B] Analysis and interpretation of SAXS/WAXS time-series experiments with software provided by the advisory team and their collaborators.

Research activities

Project category A: Development and testing of new methods for automated analyses of time-series SAXS/WAXS datasets

There are many well-defined problems available in this category. For example: time-series indexing and tracking of crystallographic reflections in WAXS; quantitative time-series analysis of anisotropic SAXS patterns; quantitative analysis of 1D and 2D multi-phase scattering problems; time-series model fitting to SAXS data; etc.

The successful candidates will mainly work in the field of quantitative image analyses with respect to diffraction data. Research activities include: image analysis, code development, model fitting, and visualisation of time-series results.

Project category B: Analysis and interpretation of SAXS/WAXS time-series experiments

We are working on the question how the coupling of stress, rock microstructure, temperature, and water-vapour pressure affect the dehydration kinetics and microstructural evolution of dehydrating gypsum rock. The successful candidates will help with analysing our large array of existing Synchrotron experiments or, timing and qualification permitting, running new experiments at the Australian Synchrotron. A wide array for research activities can be offered, from quantitative analyses of the SAXS/WAXS data to complementary imaging with scanning-electron microscopes and supplementary chemical analyses with XRF and XRD.

Outcomes

Project outcomes include:

• [a] Advances in our fundamental understanding of the coupling between stress, microstructure, and dehydration kinetics in solids
• [b] Development of novel analytical techniques for the inversion of time-series SAXS/WAXS data

All work done in this project has a very high probability to contributing to articles published in international high-impact journals. We strongly encourage and support student authorship on research papers.

Skills and experience

We would benefit most from working with students with an interest, and ideally background, in one or more of these fields:

1. Image analysis
2. Coding
3. Synchrotron science
4. (X-ray) Diffraction
5. Mathematics
6. Material Science
7. Mineralogy/Earth Science

Scholarships

You may be eligible to apply for a research scholarship.

Explore our research scholarships

Keywords

• X-ray diffraction
• Dehydration reactions
• Synchrotron science
• Gypsum
• Kinetics
• SAXS/WAXS

Contact

Contact the supervisor for more information.