Polarization of recoil protons from the reaction γp → π0p in the proton energy range 450–800 MeV

Abstract

Measurement of secondary-proton polarization from the reaction γp → π 0p have been performed in the proton energy range 500–800 MeV at c.m. pion emission angles 100°, 120°, 140°. The experiment was carried out using an optical spark chamber telescope at the output of the magnetic spectrometer. The obtained experimental data are included in a Walker-type analysis in order to verify the parameters of the resonances P 11(1470), D 13(1570) and S 11(1535). Proton polarization in the reaction γp → π 0p was measured for a photon energy of 450 MeV at a c.m. pion emission angle of 105° using photons linearly polarized at 45° to the reaction plane. A liquid hydrogen target in the field of a superconducting magnet was used for the separation of the P x′ and P z′ components of the secondary-proton polarization vector. Data are obtained for three components ( P x′ , P y , P z′ ) of the proton polarization. The obtained results are compared with predictions of different multipole analyses of photoproduction.