nan Bellini

GDH at GRAAL with polarized H D target

Within the GRAAL collaboration, we have constructed a Polarized HD Target Factory, implanted at IPN Orsay. The expected properties of the HD targets and the results already obtained for the polarization of HD samples and the relaxation times are given. New possibilities to perform GDH experiments on polarized proton, neutron and deuteron are now opened, by using the high circular polarization of the GRAAL backscattered photon beams and the large effective longitudinal polarization of the HD target, resulting essentially from its good dilution factors. Polarized total cross sections concerning the isovector Drell-Hearn Gerasimov Sum Rule related to the proton neutron difference, could be measured with minimum systematic uncertainties: the target containing both polarized protons and neutrons. An experimental method, taking advantage of the 4pi GRAAL experimental set-up is described.

Meson photoproduction at GRAAL

Precise measurements of the differential cross section and the beam polarization asymmetry E have been obtained by the GRAAL collaboration for the (gamma) over right arrow + p --> n + p and the (gamma) over right arrow + p --> pi(0) + p reactions, at incoming photon energies up to 1.48 GeV. Preliminary data are presented and compared with different theoretical calculations. First measurements of the E observable are also available for the (gamma) over right arrow + p --> K(+)Lambda reaction channel.

eta and pi degrees photoproduction on the deuteron: Beam asymmetries

Preliminary results on the beam asymmetry for the eta and pi0 photoproduction off the quasi-free proton and the quasi-free neutron in the deuteron were obtained in the energy range 0.65-1.5 GeV of the incoming photon.