Information provided by a thermal spike analysis on the microscopic processes of track formation

The author's thermal spike model is applied to ion-induced tracks in insulators and the information related to the underlying processes is reviewed. The model-independent features of the track evolution curves prove the thermal origin of the spike. The thermal diffusivity D and the gap energy do not conform with the scaling property. The heat of fusion, the melting temperature and D are discussed in the conditions of a thermal spike. A Gaussian temperature distribution with an initial width a(0)=4.5 nm can be derived from the experimental data. In high-Tc superconductors the process of track formation is affected by the band electron properties. The results prove that only a fraction (17-40%) of the electronic stopping power is transferred to the thermal spike and the contribution of the nuclear stopping power is important at low ion velocities