1. Prokhorov General Physics Institute of RAS, Vavilov str. 38, Moscow 119991 Russia
2. Moscow Institute of Physics and Technology, Institutskii per. 9, Dolgoprudny, Moscow Region 141700 Russia
3. National Research Nuclear University "MEPhI", Kashirskoe Shosse 31, Moscow 115409 Russia
4. Frantsevich Institute for Problems of Materials Science NAS, Krzhyzhanovsky str. 3, Kiev 03680 Ukraine
5. Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice, Slovakia