Final PhD Seminar
Matter that is subjected to high-energetic heavy particles typically displays structural damages. In particular, when swift heavy ions interact with the electrons of the atomic system and dissipate their energy, so-called ion tracks, cylindrical damage zones along the ion trajectory, can form. In geology, these tracks occur naturally in minerals from the spontaneous fission of radioactive impurities such as uranium isotopes. These fission tracks are essential in the field of thermochronology as they can partially anneal and shrink in length when exposed to elevated temperatures. The partial reduction can be utilized to derive the thermal history of the corresponding mineral. Inevitably, fission tracks of rocks from several thousand metres below the Earth’s surface have been thermally annealed in the presence of several thousand atmospheres pressure. However, pressure is currently not taken into account into routine fission track analysis.
In this Final PhD Seminar I am showing a detailed investigation of ion tracks in apatite and quartz, including a characterisation of their structure, formation properties, and their thermal stability under pressure. All tracks were characterised at the Australian Synchrotron in Melbourne, Australia, by means of small angle x-ray scattering (SAXS). This approach allows obtaining a precise value of the track diameter with sub-nanometer precision and without altering the track structure. The combination of well-controlled track formation and their characterisation with SAXS was used to study the creation of ion tracks under a range of different environmental parameters. In situ SAXS under pressure has allowed thermal annealing of the tracks, while monitoring their change in size.