New method to polarize protons in a storage ring and implications to polarize antiprotons

A feasibility test of a new method to polarize beams of strongly interacting charged particles circulating in a storage ring is described. The stored particles, here protons, pass through a polarized hydrogen gas target (thickness 6\ifmmode\times\else\texttimes\fi{}${10}^{13}$ H/${\mathrm{cm}}^{2}$) in the ring some ${10}^{10}$ times and become partially polarized because one spin state is attenuated faster than the other. The polarization buildup is clearly demonstrated in the present experiment.