SURFACE SWELLING OF SAPPHIRE INDUCED BY MEV AND GEV HEAVY-IONS

Alpha-Al2O3 single crystals were bombarded with MeV xenon ions from 10 (15) to 10(17) ions CM2 and GeV uranium ions from 10(11) to 10(13) ion s cm-2 to study the surface swelling of sapphire at 77 and 300 K due t o atomic collision processes (Xe) and electronic energy loss processes in the 20-45 keV/nm regime (U). The induced damage was studied by cha nneling Rutherford backscattering. Surface swelling was measured with a profilometer. The step height induced by nuclear cascades of MeV xen on increases with the ion fluence and saturates. With GeV uranium, an electronic stopping power threshold for surface swelling was observed and the step height increased with the damage for dE/dx higher than th is threshold.