1. Institute of Electrophysics; Ural Branch; Russian Academy of Sciences; ul. Amundsena 106; Ekaterinburg 620016 Russia
2. Yeltsin Ural Federal University; Yekaterinburg 620002 Russia
3. Institute of Ion Beam Physics and Materials Research; Helmholtz-Zentrum Dresden-Rossendorf (HZDR); PF 510119 Dresden 01314 Germany