A model reasoning low-energy track-formation and enhanced nuclear energy loss in Si irradiated with C60 ions

Ion energy dependence of track radius in Si was investigated under C 60 ion irradiation between 30 keV and 9 MeV. The tracks were observed from 9 MeV down to 60 keV but not at 30 keV. The track radius gradually decreased with decreasing the energy from 9 MeV to 500 keV, showing a tentative increase around 300 keV followed by further decrease. Both (i) the track formation at exceptionally low energies and (ii) the non-monotonic energy dependence of the track radius, are explained by the ion energy dependence of electronic and nuclear energy losses of C 60 ions in Si, i.e., the cluster-ion energy loss (CIEL) model.