A method to polarise antiprotons in storage rings and create polarised antineutrons

An intense circularly polarised γ -beam interacts with a cooled antiproton beam in a storage ring. Due to spin-dependent absorption cross-sections for the reaction γ+ anti p→π-+ anti n a built-up of polarisation of the stored antiprotons takes place. Figures of merit around 0.1 can be reached in principle over a wide range of antiproton energies. In this process polarised antineutrons with polarisation Pbarn succeeds 70% emerge. The method is presented for the case of a 300 MeV/c cooled antiproton beam. (orig.)