1. Frank Laboratory of Neutron Physics; Joint Institute for Nuclear Research; RU-141980 Dubna Russian Federation
2. Bogoliubov Laboratory of Theoretical Physics; Joint Institute for Nuclear Research; RU-141980 Dubna Russian Federation
3. Institute of Inorganic Chemistry; Riga Technical University; Miera Street 34 LV-2169 Salaspils Latvia
4. Institute of Solid State Physics; University of Latvia; Kengaraga Street 8 LV-1063 Riga Latvia
5. Institute of Physics; University of Tartu; Ravila 14c 50411 Tartu Estonia