[1] Belarusian State Univ, Res Inst Nucl Problems, Minsk 220030, BELARUS
[2] Vilnius State Univ, Radiophys Dept, LT-10022 Vilnius, Lithuania
[3] Bulgarian Acad Sci, Inst Mech, Open Lab Expt Mech, BU-1113 Sofia, Bulgaria
[4] ENSTIB, IJL UMR CNRS 7198, F-88026 Epinal, France
[5] Riga Tech Univ, Inst Polymer Mat, Riga, Latvia
[6] Natl Inst Nucl Phys, Frascati Natl Lab, I-00044 Frascati, Italy
[7] Univ Namur, Dept Phys, B-5000 Namur, Belgium