Kluth, PPakarinen, O. HDjurabekova, FlyuraGiulian, RRidgway, M. CByrne, A. PNordlund, K2015-11-162015-11-160021-8979http://hdl.handle.net/1885/16490We report on the observation of nanoscale density fluctuations in 2 μm thick amorphous SiO₂ layers irradiated with 185 MeV Au ions. At high fluences, in excess of approximately 5 × 10¹² ions/cm², where the surface is completely covered by ion tracks, synchrotron small angle x-ray scattering measurements reveal the existence of a steady state of density fluctuations. In agreement with molecular dynamics simulations, this steady state is consistent with an ion track “annihilation” process, where high-density regions generated in the periphery of new tracks fill in low-density regions located at the center of existing tracks.The authors acknowledge the Australian Research Council and the Australian Synchrotron Research Program for financial support and thank the staff at the ANU Heavy Ion facility for their continued technical assistance. O.P., F.D., and K.N. acknowledge financial support from the Academy of Finland under its Centre of Excellence program as well as the OPNA project, and grants of computer capacity from CSC.http://www.sherpa.ac.uk/romeo/issn/0021-8979..."Publishers version/PDF may be used on author's personal website, institutional website or institutional repository" from SHERPA/RoMEO site (as at 16/11/15). Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics and may be found at https://doi.org/10.1063/1.3671614Keywords: Annihilation process; Density fluctuation; Fluences; High-density regions; Ion track; Molecular dynamics simulations; Nano scale; Small angle X-ray scattering; Steady state; Swift heavy ions; Molecular dynamics; Nanotechnology; Silicon compounds2011-11-2310.1063/1.36716142016-02-24