Hyperon polarisation in the reaction p bar {sup 12} C {yields}{lambda} bar {lambda} X

Data from the p-bar {sup 12} C {yields}{lambda}-bar {lambda} X reaction, collected by the PS185 experiment at antiproton momenta around 1.44 GeV/c, 1.66 GeV/c and 1.77 GeV/c, have been analyzed and the {lambda} and {lambda}-bar polarisations have been extracted. The events are classified as quasi-free or non-quasi-free and it is found that the polarisations for {lambda} and {lambda}-bar differ in the latter case. Such an effect comes from differences in the interaction of the outgoing {lambda} and {lambda}-bar with the residual nucleus and the measurement constitutes the first information on {lambda}-bar interaction with nuclear matter.