Positive pion photoproduction from hydrogen at photon energies between 500 MeV and 1,400 MeV in forward direction

The differential cross section of the reaction #betta#+p->π+-n was measured at pion CM-angles of 200 and 300 for photon energies between 500 MeV and 1,400 MeV. The pions were detected in a magnetic spectrometer. By measuring each pion trajectory and by offline calculation of the initial pion parameters an energy resolution of about 2.5% FWHM was achieved. The results complete a set of data which were measured in recent years at the Bonn 2.5 GeV synchrotron. In comparison to photoproduction analyses two effects were revealed: the eta cusp appears in the energy dependence of the cross section as a sharp drop at Ksub(#betta#)=710 MeV. In the region of the third resonance the data show a greater enhancement that predicted by most of the analyses. (orig.)