Billy Rayner

Development of lab-based X-ray computed tomography, to be applied to the study of geological materials at high pressure and temperature.

PhD project title:

X-ray tomography of geological materials at extreme conditions

Project description:

Billy rayner

The structure and composition of the Earth’s deep interior cannot be directly measured, but instead must be inferred from indirect geophysical observations, predominantly the interpretation of seismic velocity data. This approach relies on the availability of high-quality data for the seismic properties of all the potential deep Earth minerals, fluids and melts. Despite their importance for understanding the basic properties of the deep Earth, there are very few measurements of seismic properties for minerals or melts at the pressure and temperature conditions of the deep Earth. Currently, instead of using data, we rely on large extrapolations of low pressure and temperature data or on theoretical estimates.

My PhD project aims to extend recently developed techniques at UCL for performing lab-based measurements of the physical properties of Earth at high pressure and temperature conditions. In these experiments high-pressure samples contained within a Paris-Edinburgh press are imaged using X-rays to observe changes in their internal structure. By collecting multiple X-ray radiographs as the sample is rotated, a micro-resolution 3-dimensional tomogram of the sample’s internal structure may be generated. Measurements can be performed at upper mantle conditions extending to ~ 10 GPa and > 1200 K, which makes the scope for this technique extremely broad and exciting.

The current aim of the project, once our ability to image objects at high pressure and temperature within the Paris-Edinburgh press has been established, is to measure the densities/compressibilities of hydrous felsic melts, which has potential applications to computational modelling of volcanic processes.

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