[1] Lomonosov Moscow State Univ, Dept Phys, Moscow 119991, Russia
[2] Lomonosov Moscow State Univ, Skobeltsyn Inst Nucl Phys, Moscow 119991, Russia
[3] Tartu Univ, Inst Phys, EE-50411 Tartu, Estonia
[4] Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia
[5] All Russia Sci Res Inst Mineral Raw Mat Synth, Aleksandrov, Russia