V.I. Ponomarenko – Dr.Sc.(Phys.-Math.), Professor, 
Department of Experimental Physics, V.I. Vernadsky Crimean Federal University (Simferopol) E-mail: vponom@gmail.com

I.M. Lagunov – Senior Lecturer, 
Department of Experimental Physics, V.I. Vernadsky Crimean Federal University (Simferopol)
E-mail: lagunov.igor@gmail.com