[1] Inst Nucl Res, MSP, UA-03680 Kiev, Ukraine
[2] Ist Nazl Fis Nucl, I-50019 Florence, Italy
[3] Univ Florence, Dipartimento Fis, I-50019 Florence, Italy
[4] Inst Scintillat Mat, UA-61001 Kharkov, Ukraine
[5] Nikolaev Inst Inorgan Chem, Novosibirsk 630090, Russia
[6] Inst Mat, UA-79031 Lvov, Ukraine
[7] Lashkaryov Inst Semicond Phys, UA-03028 Kiev, Ukraine