1. Czech Technical University in Prague, Faculty of Electrical Engineering, Technicka 2, 16627 Prague 6, Czech Republic
2. Institute of High Current Electronics SB RAS, 2/3 Akademichesky Ave., 634055 Tomsk, Russia
3. National Research Tomsk Polytechnic University, 30 Lenina Ave., 634050 Tomsk, Russia
4. Institute of Physics, ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
5. Nuclear Physics Institute, ASCR, Na Truhlarce 39, 18086 Prague 8, Czech Republic