Acknowledgments
This study was supported by the European Union Structural
Funds Grant ‘‘LASTER’’ (No. VP1-3.1-ŠMM-10-V-02-027) and
was partly supported by sponsorship from the Department of
Nuclear Research, Institute of Physics, Center for Physical
Sciences and Technology. The authors are grateful to Artūras
Plukis, Vidmantas Remeikis, and Mindaugas Gaspariūnas for
their expertise