1. Department of Nuclear Physics and Biophysics , Faculty of Mathematics, Physics and Informatics, , Mlynská dolina F-1, Bratislava 841 04, Slovak Republic
2. Comenius University , Faculty of Mathematics, Physics and Informatics, , Mlynská dolina F-1, Bratislava 841 04, Slovak Republic
3. Geophysical Division, Earth Science Institute, Slovak Academy of Sciences , Dúbravská cesta 9, Bratislava 840 05, Slovak Republic