Swift heavy ion irradiation (SHI) of a solid can produce narrow trails of permanent damage along the ion paths, so called ion tracks. These nanometric objects are interesting in a variety of disciplines including materials science and engineering, nuclear physics, geochronology, archaeology, and interplanetary science. Though average structural properties of ion tracks can often be inferred from macroscopic measurements, the inner track structure remains extremely difficult to retrieve due to the lack of sufficient contrast inherent with most techniques. Small angle x-ray scattering (SAXS) provides an interesting tool to study structural details of ion tracks as it is sensitive to small density changes that often exist in the damaged regions. The presentation will give an overview of our recent results on SHI damage in a variety of materials including amorphous and crystalline SiO₂, natural minerals such as apatite and olivine, amorphous metallic alloys, and semiconductors such as InP. A focus will be put on amorphous SiO₂ (a-SiO₂). Here, a fine structure in the radial density distribution comprising a cylindrical core-shell configuration is apparent. At high ion fluences, i.e. where the material experiences multiple coverage with ion tracks, results are consistent with a track “annihilation process”. The annealing kinetics were studied using in-situ SAXS measurements where complete ion track recovery was observed at a temperature of approximately 950ºC. The influence of the ion track structure in a-SiO₂ on the shaping of embedded metal nanoparticles will be discussed. The results are complemented by molecular dynamics (MD) simulations and calculations using an inelastic thermal spike (ITS) model.

Patrick Kluth*, The Australian National University, Australia
Boshra Afra, The Australian National University, Australia
Matias Rodriguez, The Australian National University, Australia
Raquel Giulian, The Australian National University, Australia
Mark C. Ridgway, The Australian National University, Australia
David J. Sprouster, The Australian National University, Australia
Leandro L. Araujo, The Australian National University, Australia
James Leslie, The Australian National University, Australia
Aidan P. Byrne, The Australian National University, Australia
Claudia S. Schnohr, Friedrich-Schiller-Universität Jena, Germany
Olli H. Pakarinen, University of Helsinki, Finland
Flyura Djurabekova, University of Helsinki, Finland
Kai Nordlund, University of Helsinki, Finland
Nigel Kirby, Australian Synchrotron, Australia
Christina Trautmann, GSI Helmholtz Center for Heavy Ion Research, Germany
Marcel Toulemonde, Centre interdisciplinaire de recherche sur les Ions, les Materiaux et la Photonique, France
Giancarlo Rizza, Ecole Polytechnique, France
Maik Lang, University of Michigan, United States
Rodney C. Ewing, University of Michigan, United States

*presenting author