Experimental study of point-defect creation in high-energy heavy-ion tracks

Thin platelets of LiF crystals have been bombarded on the side with Ne (40 MeV/amu), Ar (60 MeV/amu), Kr (42 MeV/amu), and Xe (27 MeV/amu) ions at room temperature in the dose range from ${10}^8$ to ${10}^{13}$ ions ${\mathrm{cm}}^{\mathrm{-}2}$. Taking into account the large penetration depths of these high-energy ions (≃1.4, 1.8, 0.6, and 0.2 mm for Ne, Ar, Kr, and Xe, respectively), it was possible to measure the depth distribution profiles of primary point defects (F centers) and aggregated defects (${\mathit{F}}_2$ centers) using a microspectrophotometric technique. These defects are localized in tracks surrounding the ion trajectories in which the energy is deposited by the δ rays emitted. Concerning the creation of primary defects, it has been shown that each individual track is saturated with F centers (≃4×${10}^{18}$ F centers/${\mathrm{cm}}^3$). From the evolution of the F center depth profiles as a function of the ion doses, using a model of saturated tracks, it has been possible to determine the radii of the tracks all along the ion trajectories.