[1] Univ Basque Country, Fac Quim, Dept Fis Mat, E-20080 San Sebastian, Spain
[2] Univ Basque Country, Escuela Univ Politecn, Dept Fis Aplicada 1, San Sebastian 20018, Spain
[3] AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, PL-30059 Krakow, Poland
[4] Magnet & Cryoelect Syst Ltd, Moscow 121351, Russia