Measurement of the polarization of the Λ0 in the reaction γ + p → K+ + Λ0 in the resonance region

At the Bonn 2.5 GeV synchrotron the polarization of the Λ⁰ was measured at 40° and 90° for three energies. The kaon was detected with a strong focussing magnetic spectrometer and separated from other particles with the help of a differential liquid ?erenkov counter. The polarization was determined by means of the angular distribution of the decay proton which was measured with a combination of sonic spark chambers and a scintillation counter hodoscope. The typical statistical errors are about 13%. The systematic errors add up to 8%.