Transient metal-like electrical conductivity in swift heavy ion irradiated insulators

The irradiation of insulators with swift heavy ions leads to a transient excitation of valence band electrons into the targets conduction band. The population of the conduction band gives rise to an increased electrical conductivity of the intrinsically non-conductive insulator. Due to the transient nature of the number density of excited electrons in the conduction band, the electrical conductivity is also strongly time dependent. In this work it is demonstrated how the transient electrical conductivity can be evaluated on the basis of a combination of the Monte Carlo method and a two temperature model. As a model system, the irradiation of SiO2 with 11.4 MeV/u Ca ions, corresponding to a stopping power of dE/dx=2.7dE/dx=2.7 keV/nm, is chosen for the calculations. It is found, that the enhancement of the electrical conductivity is quite large and comparable to that of metals like gold. The striking magnitude of this enhancement may allow for an experimental measurement of the electrical conductivity of insulators during irradiation with swift heavy ions.