The size of thermal spikes in xenon-irradiated Ag/Fe bilayers

Ag/Fe bilayers in which a submonolayer of In-111 had been deposited in the Fe layer at a distance of x = 0-17 nm from the interface, were irradiated a t 80 K with 450 keV Xe ions to a fluence of 3 and 6 . 10(15) ions/cm(2). Pe rturbed Angular Correlation spectroscopy was used to monitor the microsurro unding of the In-111 tracers and to identify the radiation-induced defects. The fraction of tracer atoms being transported into the Ag layer cannot be explained by ballistic mixing, but is reproduced when assuming local therm al spikes to develop. The diffusion of In-111 into the Ag layer can be mode led if the local spikes have an average diameter of some 5 nm.