1. FLNR; JINR; Joliot-Curie 6 141980 Dubna Russia
2. Center for Free-Electron Laser Science at DESY; Notkestr. 85 22607 Hamburg Germany
3. NRC Kurchatov Institute; Kurchatov Sq. 1 123182 Moscow Russia
4. LPI of the Russian Academy of Sciences; Leninskij Prospekt, 53 119991 Moscow Russia