Polarization Measurements at PETRA

Recent measurements of beam polarization in the electron-positron storage ring PETRA are presented. A method is described for compensating the depolarizing effects caused by vertical closed orbit distortions. This technique has been successfully applied, and reproducible polarization up to 80 % has been obtained both in single beam and colliding beam operation with luminosities of about 3 · 1030 cm-2S-1· Polarization measurements as a diagnostic tool for studying other beam parameters such as absolute energy and momentum compaction factor are also briefly described. These latter measurements have been performed with the help of a fast depolarizing device.