1. Institute of Experimental Physics SAS, Watsonova 47, 04001 Košice, Slovakia
2. Institute of Nuclear Sciences Vinca, University of Belgrade, 11001 Belgrade, Republic of Serbia
3. Faculty of Science,P.J. Šafárik University, Moyzesova 11, 04001 Košice, Slovakia
4. Institute of Geotechnics SAS, Watsonova 45, 04001 Košice, Slovakia