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We report on new measurements of the beam asymmetry for. photoproduction on protons and neutrons in hydrogen and deuterium targets from the GRAAL Collaboration. The beam asymmetry values are extracted from the reaction threshold (E-gamma = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the three-pion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement, leading to the world's most precise measurements of the beam asymmetry for omega photoproduction off free protons. First experimental results on the deuteron allow the extraction of the Sigma beam asymmetry on quasifree nucleons. The beam asymmetry angular distributions obtained for the free and the quasifree kinematics show the same behavior, similar to the findings in pseudoscalar meson photoproduction reactions. First results of the beam asymmetry on the quasifree neutrons are presented, showing different strengths and angular distributions from the results on the proton target.

First measurement of the beam asymmetry $\ensuremath{\Sigma}$ for Compton scattering off the proton in the energy range ${E}_{\ensuremath{\gamma}}=0.85--1.25\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$ is presented. The data reveal two narrow structures at ${E}_{\ensuremath{\gamma}}=1.036$ and ${E}_{\ensuremath{\gamma}}=1.119 \mathrm{GeV}$. They may signal narrow resonances with masses near 1.68 and $1.72\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$, or they may be generated by the sub-threshold $K\ensuremath{\Lambda}$ and $\ensuremath{\omega}p$ production. Their decisive identification requires additional theoretical and experimental efforts.

The study of quasifree Compton scattering on the neutron in the energy range of E{sub {gamma}}=0.75-1.5 GeV is presented. The data reveal a narrow peak at W{approx}1.685 GeV. This result, being considered in conjunction with the recent evidence for a narrow structure at W{approx}1.68 GeV in {eta} photoproduction on the neutron, suggests the existence of a nucleon resonance with unusual properties: a mass M{approx}1.685 GeV, a narrow width {Gamma}{

The -beam asymmetry {Sigma} in the photoproduction of negative pions on quasi-free neutrons in a deuterium target was measured at the Grenoble Anneau Accelerateur Laser in the energy interval 700-1500 MeV and over a wide angular range, using polarized and tagged photons. Results are compared with recent partial-wave analyses.