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Now showing items 17 - 21 of 21

  • BEAM ASYMMETRY Sigma OF THE pi(-) PHOTOPRODUCTION OFF NEUTRON RID B-1239-2012 RID A-2439-2012

    Mandaglio, G.   Bellini, V.   Bocquet, J. P.   Casano, L.   D'Angelo, A.   Di Salvo, R.   Fantini, A.   Franco, D.   Gervino, G.   Ghio, F.   Giardina, G.   Girolami, B.   Giusa, A.   Ignatov, A. S.   Lapik, A. M.   Sandri, P. Levi   Lleres, A.   Mammoliti, F.   Manganaro, M.   Moricciani, D.   Mushkarenkov, A. N.   Nedorezov, V. G.   Randieri, C.   Rebreyend, D.   Rudnev, N. V.   Russo, G.   Schaerf, C.   Sperduto, M. L.   Sutera, M. C.   Turinge, A.   Vegna, V.  

    We present the analysis of data performed in order to identify the events of the gamma + n -> pi(-) + p reaction obtained by bombarding a liquid Deuterium target with a polarised. beam of 0.55-1.5 GeV at the Graal-experiment. We show the effect of different kinematic and hardware constraints used to reduce the contamination coming from the concurrent reaction channels. By the simulation we estimate the contamination degree due to the other reaction channels so we can test the reliability of our method. We describe a new three-dimensional cut based on the Fermi momentum reconstruction and its effect on the suppression of the concurrent double charged pion photoproduction. We present the preliminary beam asymmetry Sigma of the pi(-) fotoproduction off quasi-free neutron up to about theta(c.m.), (pi-) = 165 degrees together with some theoretical multipolar analysis. For a comparison we also report the data present in literature on the same reaction for E(gamma) -850-1740 MeV and theta(c.m.), (pi-) <= 105 degrees.
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  • Measurement of beam-recoil observables O(x), O(z) and target asymmetry T for the reaction gamma p -> K(+)Lambda

    Lleres, A.   Bartalini, O.   Bellini, V.   Bocquet, J. P.   Calvat, P.   Capogni, M.   Casano, L.   Castoldi, M.   D'Angelo, A.   Didelez, J. -P.   Di Salvo, R.   Fantini, A.   Franco, D.   Gaulard, C.   Gervino, G.   Ghio, F.   Girolami, B.   Giusa, A.   Guidal, M.   Hourany, E.   Kunne, R.   Kuznetsov, V.   Lapik, A.   Sandri, P. Levi   Mammoliti, F.   Mandaglio, G.   Moricciani, D.   Mushkarenkov, A. N.   Nedorezov, V.   Nicoletti, L.   Perrin, C.   Randieri, C.   Rebreyend, D.   Renard, F.   Rudnev, N.   Russew, T.   Russo, G.   Schaerf, C.   Sperduto, M. -L.   Sutera, M. -C.   Turinge, A.   Vegna, V.  

    The double polarization (beam-recoil) observables O(x) and O(z) have been measured for the reaction gamma p -> K(+) Lambda from threshold production to E gamma similar to 1500 MeV. The data were obtained with the linearly polarized beam of the GRAAL facility. Values for the target asymmetry T could also be extracted despite the use of an unpolarized target. Analyses of our results by two isobar models tend to confirm the necessity to include new or poorly known resonances in the 1900 MeV mass region.
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  • Complete Photo-production Experiments

    D'Angelo, A.   Ardashev, K.   Bade, C.   Bartalini, O.   Bellini, V.   Blecher, M.   Bocquet, J. -P.   Capogni, M.   Caracappa, A.   Casano, L. E.   Castoldi, M.   Di Salvo, R.   Fantini, A.   Franco, D.   Gervino, G.   Ghio, F.   Giardina, G.   Gibson, C.   Girolami, B.   Giusa, A.   Gluekler, H.   Hicks, K.   Hoblit, S.   Honig, A.   Kageya, T.   Khandaker, M.   Kistner, O. C.   Kizilgul, S.   Kucuker, S.   Lapik, A.   Lehmann, A.   Sandri, P. Levi   Lleres, A.   Lowry, M.   Lucas, M.   Mahon, J.   Mammoliti, F.   Mandaglio, G.   Manganaro, M.   Miceli, L.   Moricciani, D.   Mushkarenkov, A.   Nedorezov, V.   Norum, B.   Pap, M.   Preedom, B.   Seyfarth, H.   Randieri, C.   Rebreyend, D.   Rudnev, N.   Russo, G.   Sandorfi, A.   Schaerf, C.   Sperduto, M. -L.   Stroeher, H.   Sutera, M. -C.   Thorn, C. E.   Turinge, A.   Vegna, V.   Whisnant, C. S.   Wang, K.   Wei, X.  

    The extraction of resonance parameters from meson photo-reaction data is a challenging effort, that would greatly benefit from the availability of several polarization observables, measured for each reaction channel on both proton and neutron targets. In the aim of obtaining such complete experiments, polarized photon beams and targets have been developed at facilities, worldwide. We report on the latest results from the LEGS and GRAAL collaborations, providing single and double polarization measurements on pseudo-scalar meson photo-production from the nucleon.
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  • Observation of Narrow N (+)(1685) and N (0)(1685) Resonances in (gamma) N -> pi eta N Reactions

    Kuznetsov, V.   Mammoliti, F.   Tortorici, F.   Bellini, V.   Brio, V.   Gridnev, A.   Kozlenko, N.   Russo, G.   Sperduto, M. L.   Sumachev, V.   Sutera, C.  

    Observation of a narrow structure at W similar to 1.68 GeV in the excitation functions of some photon- and pion-induced reactions may signal a new narrow isospin-1/2 N(1685) resonance. New data on the (gamma) N -> pi eta N reactions from GRAAL seems to reveal the signals of both N (+)(1685) and N (0)(1685) resonances.
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  • Nucleon form factor studies at JLab RID B-1239-2012

    Giusa, A.   Bellini, V.   Mammoliti, F.   Russo, G.   Sperduto, M. L.   Sutera, C. M.   Cisbani, E.   Garibaldi, F.   Urciuoli, G. M.   Capogni, M.   Cates, G. D.   de Jager, K.   Wojtsekhowski, B.  

    The ratio of the electromagnetic proton elastic form factors, G(E)(p)/G(M)(p), has been measured at Jefferson Lab up to Q(2) approximate to 9 (GeV/c)(2), by using the CEBAF 6 GeV electron beam, and revealing an unexpected and challenging physical behaviour. The 2014 scheduled 12 GeV upgrade will allow the measurement of G(E)(p)/G(M)(p) up to Q(2) approximate to 15 (GeV/c)(2), by taking advantage of the new large-acceptance forward spectrometer Super BigBite (SBS) in Hall A. Measurements of neutron form factors in the region around 10 (GeV/c)(2), where quark confinement plays an important role, are expected to show the behaviour already observed in the proton case. (C) 2010 Elsevier Ltd. All rights reserved.
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