Compton scattering by the proton

Compton scattering by the proton has been measured over a wide range coveri ng photon energies 250 MeV less than or similar to E-gamma less than or sim ilar to 800 MeV and photon scattering angles 30 degrees less than or simila r to theta (lab)(gamma) less than or similar to 150 degrees, using the tagg ed-photon facility at MAMI (Mainz) and the large-acceptance arrangement LAR A. The data are in good agreement with the dispersion theory based on the S AID-SM99K parameterization of photo-meson amplitudes. From the subset of da ta between 280 and 360 MeV the resonance pion-photoproduction amplitudes we re evaluated leading to the multipole E2/M1 ratio EMR(340 MeV) = (-1.6 +/- 0.4(stat+syst) +/- 0.2(model))% From all data below 455 MeV the proton's ba ckward spin polarizability was determined to be gamma pi = (-37.9 +/- 0.6(s tat+syst) +/- 3.5(model)) x 10(-4) fm(4). (C) 2001 Elsevier Science B.V. Al l rights reserved.