We present recent Graal results on beam-polarization asymmetries in the photoproduction of η meson on protons and neutrons in Hydrogen and Deuterium for the incoming photon energy range from threshold to 1.5 GeV. Data have been obtained using the tagged and linearly polarized photon beam and the large solid angle apparata of the Graal facility, located at the ESRF in Grenoble (France).The comparisons between the free and bound (in the deuteron) proton and between bound proton and bound neutron are shown. In particular we measured for the first time the beam asymmetry Σ in the η photoproduction on the bound neutron. Data have been obtained from a deuteron target, selecting η events from both bound necleons in the quasi-free kinematics. In this kinematical condition the results obtained from free and quasi-free proton are almost identical within the experimental errors; hence we deduce that nuclear effects are negligible when measuring the beam-polarization asymmetries for η photoproduction on the quasi-free nucleon.
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V. Bellini, A. Giusa, F. Mammoliti, C. Randieri, G. Russo, M. L. Sperduto, M. C. Sutera, G. Giardina, G. Mandaglio, M. Manganaro, O. Bartalini, A. D’Angelo, A. Fantini, L. Nicoletti, C. Schaerf, L. Casano, R. Di Salvo, D. Moricciani, M. Capogni, P. Levi Sandri, G. Gaulard, B. Girolami, F. Ghio, J. P. Bocquet, P. Calvat, A. Lleres, D. Rebreyend, F. Renard, T. Russew, J. P. Didelez, M. Guidal, E. Hourany, R. Kunne, A. Lapik, A. N. Mushkarenkov, V. Nedorezov, R. Rudnev, A. Turinge, M. Castoldi, G. Gervino, V. Kouznetsov (2008).
Nuclear Physics A – Vol. 805, pp. 84-86, ISSN: 0375-9474, doi: 10.1016/j.nuclphysa.2008.02.032.
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Nuclear Physics A focuses on the domain of nuclear and hadronic physics and includes the following subsections: Nuclear Structure and Dynamics; Intermediate and High Energy Heavy Ion Physics; Hadronic Physics; Electromagnetic and Weak Interactions; Nuclear Astrophysics. The emphasis is on original research papers. A number of carefully selected and reviewed conference proceedings are published as an integral part of the journal. Conference proceedings on the topics covered by Nuclear Physics A are published in the (separately available) journal Nuclear and Particle Physics Proceedings.
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