Spin effects in pp-bar interaction and their possible use to polarize antiproton beams

The polarization buildup in a pp-bar beam which is due to the interaction of stored antiprotons with polarized protons of a hydrogen target is considered. The corresponding cross section is calculated using the Paris nucleon-antinucleon optical potential in the energy interval 20<Tlab<100 MeV. It follows from this estimate that, at realistic parameters of a storage ring and a target, the filtering mechanism can provide a noticeable polarization in a time comparable with the beam lifetime