Title: Single-Pass Lazer Polarization of Ultrarelativistic Positrons

Abstract: The new method for producing of the polarized relativistic positrons is suggested. A beam of unpolarized positrons accelerated up to a few GeV can be polarized during a head-on collision with an intense circularly polarized lazer wave. After a multiple Compton backscattering process the initial positrons may lose a substantial part of its energy and, as consequence, may acquire the significant longitudinal polarization. The simple formulas for the final positron energy and polarization degree depended on the laser flash parameters have been obtained. The comparison of efficiences for the suggested technique and known ones is carried out. Some advantages of the new method were shown.