Ways to make polarized antiproton beams

For producing polarized antiproton beams the so called spin filter method is normally discussed. The method has been proven by the FILTEX collaboration with a proton beam and detailed studies are presently performed by the PAX collaboration at COSY. A well known source for polarized antiprotons is the antilambda decay. It was used in the only experiment with polarized $\bar{p}$ antiprotons so far at FERMILAB. Furthermore the antiproton production process itself, if showing polarization, would be by far the simplest and best way to get polarized beams because one could use the existing antiproton facility. Up to now $\bar{p}$ production has never been investigated in detail.