Effect of stimulated radiation processes on formation of tracks and   nanocavities in solids
  It is shown that the average diameter of tracks produced by swift heavy ions in metals is determined by the size of elementary resonator. The last is introduced in the theory of thermal radiation accounting for the stimulated radiation processes. Due to the inverse density gradient, radiation produced by electronic excitations is locked in the region of track which is formed. Similar effects are applied to the process of nanocavity formation in semiconductors during ion irradiation. 
F.V.Prigara