Starting from 1996 February GRAAL photon beam is operated at ESRF storage ring in Grenoble (France). The tagged and polarized photon beam is obtained by means of the Compton backscattering technique of the light produced by an Argon laser at energy 2.41 eV or 3.53 eV against ultrarelativistic electrons of 6 GeV energy. The Compton scattering is determined, as well known, by a two body kinematics and the energy of the scattered photons gets a maximum for backscattering processes and equal to 1500 Me V in the case of the GRAAL beam. By changing the laser energy row it’s possible to vary easily the maximum energy of the photon beam. A further property of the beams produced by means of this technique, is their high polarization degree. Namely the electron which scatters is ultrarelativistic and its elicity is a good quantum number; hence the polarization of the scattered photon is the same of the incident photon, linear or circular. We already reported preliminary results concerning meson photoproduction at several Conferences, see for example the report, and articles holding partial results about the η and π+ photoproduction have been already published. Now we made it available a complete set of data, here reported, concerning the π and η photoproduction and including both angular distributions and cross sections as a function of the incident photon energy. Data have been obtained by using the full setup of GRAAL detectors: the very large sol id angle 4π -BGO together with the energy tagger for the photon beam and the scintillating fibers-lead beam quantameter.
O. Bartalini, V. Bellini, J. P. Bocquet, M. Capogni, M. Castoldi, A. D’Angelo, J. P. Didelez, R. Di Salvo, D. Garozzo, G. Gervino, F. Ghio, B. Girolami, M. Guidal, E. Hourany, I. Kilvington, V. Kouznetsov, F. Kunne, A. Lapik, P. Levi Sandri, A. Lleres, D. Moricciani, V. Nedorezov, L. Nicoletti, D. Rebreyend, F. Renard, C. Randieri, M. Sanzone, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge, A. Zucchiatti (2001).
Communication to the Conference Hadron Structure 2000 Stara Lesna, High Tatra Mountains, Slovak Republic, 2-8 October 2000.