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Now showing items 1 - 13 of 13

  • Vertex identification of events in photonuclear reactions by cylindrical multiwire proportional chambers RID B-7657-2011 RID B-1239-2012

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

    In the framework of investigation of meson photo-production on proton and neutron in a deuterium target at the GRAAL experiment, we present a method to identify the vertex of interaction when in reaction products there are at least two charged particles, by the information provided by the cylindrical multiwire proportional chambers. By this device, we are able to obtain the direction of charged particles that leave the target after a photo-production reaction. For each charged particle, the device provides the coordinates of two points in the laboratory reference system, and the z-axis represents the beam direction. We calculate the trajectory of each charged particle and its cross point, representing the vertex of the reaction.
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  • Position sensitive disc for charged particle detection

    Bellini, V.   Palazzolo, F.   Scire, A.   Sperduto, M.L.   Albergo, S.   Poli, G.   Potenza, R.   Randieri, C.   Russo, V.   Sutera, M.C.   Capogni, M.   Schaerf, C.   D'angelo, A.   Moricciani, D.   Kuznetsov, A.V.   Girolami, B.   Ghio, F.  

    A plastic scintillating disc (NE102, 3 cm thick, 1 m diameter) has been designed for detecting charged pions in nuclear reactions at intermediate energy. A hole of 20 cm diameter was made in the middle of the disc in order to allow for the beam passage through the detector. The originality of the detector consists of the simultaneous use of four very compact central photomultiplier tubes (PMT) and eight peripheral PMTs in order to retrieve the hitting point of a charged particle onto the disc surface with a space resolution of plusmn3 cm. The original method has been developed by using polar coordinates and only the time-of-flight information (TOF) from three or four nearest PMTs, including at least one central PMT
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  • Measurement of Sigma beam asymmetry in pi(0) photoproduction off the neutron in the second and third resonances region

    Di Salvo, R.   Fantini, A.   Mandaglio, G.   Mammoliti, F.   Bartalini, O.   Bellini, V.   Bocquet, J. P.   Casano, L.   D'angelo, A.   Didelez, J. P.   Franco, D.   Gervino, G.   Ghio, F.   Giardina, G.   Girolami, B.   Giusa, A.   Guidal, M.   Hourany, E.   Kunne, R.   Lapik, A.   Sandri, P. Levi   Lleres, A.   Manganaro, M.   Moricciani, D.   Mushkarenkov, A. N.   Nedorezov, V.   Randieri, C.   Rebreyend, D.   Rudnev, N.   Russo, G.   Schaerf, C.   Sperduto, M. L.   Sutera, M. C.   Turinge, A.   Vegna, V.   Fix, A.   Kamalov, S. S.   Tiator, L.  

    The Sigma beam asymmetry in the photoproduction of neutral pions from quasi-free nucleons in a deuteron target was measured for the first time between 0.60 and 1.50 GeV, with the GRAAL polarized and tagged photon beam. The asymmetry values from the quasi-free proton were found equal to the ones extracted from a pure proton target. The asymmetries from quasi-free proton and quasi-free neutron were found equal up to 0.82 GeV and substantially different at higher energies. The results are compared with recent partial-wave analyses.
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  • Measurement of eta photoproduction on the proton from threshold to 1500 MeV RID B-1239-2012 RID A-2439-2012

    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.   Giardina, G.   Girolami, B.   Giusa, A.   Guidal, M.   Hourany, E.   Kunne, R.   Lapik, A.   Sandri, P. Levi   Lleres, A.   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.  

    Beam asymmetry and differential cross-section for the reaction gamma p -> eta p were measured from production threshold to 1500MeV photon laboratory energy. The two dominant neutral decay modes of the eta-meson, eta -> 2 gamma and eta -> 3 pi(0) , were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.
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  • Charged particle detection at GRAAL RID B-1239-2012

    Mammoliti, F.   Bellini, V.   Giusa, A.   Randieri, C.   Russo, G.   Sperduto, M. L.   Sutera, M. C.   D'Angelo, A.   Di Salvo, R.   Fantini, A.   Franco, D.   Moricciani, D.   Schaerf, C.   Vegna, V.   Sandri, P. Levi   Mandaglio, G.   Giardina, G.  

    Experimental results on proton and charged pion detection obtained from a study of the +np+- reaction are reported in detail. Data have been collected using the tagged and linearly polarized photon beam, impinging on a deuterium target, and the large solid angle apparatus of the GRAAL facility in Grenoble (France). The energy of the charged particles was measured using a BGO calorimeter. A comparison of the experimental data with a GEANT3-based simulation is also presented.
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  • Results from polarized experiments at LEGS and GRAAL

    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   Lieres, 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.   Stroher, H.   Sutera, M. -C.   Thorn, C. E.   Turinge, A.   Vegna, V.   Whisnant, C. S.   Wang, K.   Wei, X.  

    Compton backscattering gamma ray beams are characterized by a high degree of linear and circular polarization with low unpolarized backgrounds and have proven to provide very precise measurements of polarization observables. Latest results from LEGS and GRAAL experiments on proton and deuteron targets are presented. The Sigma beam asymmetry for omega photoproduction has been measured by the GRAAL collaboration for both the omega -> pi(0)gamma and the omega -> pi(+)pi(+)pi(0) decay channels on the proton target; single and double polarization asymmetries have been provided also for the K photoproduction channel. E and G double polarization asymmetries for single pion photoproduction on the proton and deuteron have been measured at LEGS using a frozen spin HD target.
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  • PHOTOPRODUCTION OF pi(0)pi(+) ON THE PROTON AND DEUTERON AT E(gamma)=0.7-1.5 GeV RID B-1239-2012 RID A-2439-2012 RID B-7657-2011

    Mushkarenkov, A.   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.   Lapik, A.   Sandri, P. Levi   Lleres, A.   Mammoliti, F.   Mandaglio, G.   Manganaro, M.   Moricciani, D.   Nedorezov, V.   Randieri, C.   Rebreyend, D.   Rudnev, N.   Russo, G.   Schaerf, C.   Sperduto, M. L.   Sutera, M. C.   Turinge, A.   Vegna, V.  

    The preliminary results obtained by the GRAAL collaboration for the pi(0)pi(+) photoproduction on the free and quasi-free proton (deuteron) at E(gamma) = 0.7-1.5 GeV are presented. The total cross section of the gamma p -> pi(0)pi(+)n reaction and invariant mass spectra for the pi(+)pi(0), pi(+)n and pi(0)n systems are presented in the photon energy range from 0.7 to 1.5 GeV. These results are in good agreement with the 2 pi-MAID calculations.
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  • Polarization observable measurements for gamma p -> K+ Lambda and gamma p -> K+ Sigma(0) for energies up to 1.5 GeV RID B-1239-2012

    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.   Gaulard, C.   Gervino, G.   Ghio, F.   Girolami, B.   Giusa, A.   Guidal, M.   Hourany, E.   Kouznetsov, V.   Kunne, R.   Lapik, A.   Sandri, P. Levi   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.  

    Beam asymmetries and hyperon recoil polarizations for the reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma(0) have been measured from the threshold production to 1500 MeV with the GRAAL facility located at the ESRF in Grenoble. These results complement the database for the beam asymmetry, covering for the first time the production threshold region. Recent theoretical analyses are presented for which the beam asymmetry data bring interesting new information and allow to better determine some resonance parameters. Most importantly, these results strengthen the need of a new D-13 state around 1900 MeV.
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  • omega PHOTOPRODUCTION AT GRAAL RID B-1239-2012 RID A-2439-2012 RID B-7657-2011

    Vegna, V.   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.   Lleres, A.   Sandri, P. Levi   Mammoliti, F.   Mandaglio, G.   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.  

    The study of meson photoproduction on the nucleon is a very important tool to complete the puzzle of baryon excited states. GRAAL aim is the measurement of cross sections and of beam asymmetries for all the photonuclear reactions accessible in the energy range from 600 MeV up to 1.5 GeV. In the following preliminary results of the Sigma beam asymmetry for omega photoproduction on the free proton in Hydrogen and on the quasi-free nucleon in Deuterium are shown. GRAAL is the first experiment in which both the charged and the radiative decay of omega meson are studied. Since the beam asymmetry is independent of the decay mode, the comparison of the results from the two channel allows an important check on data consistency. Results on the free proton are in good agreement with theoretical prediction from Zhao model and confirm the presence of P(13)(1720) state. The analysis performed for the radiative decay is applied to the process of. photoproduction on the quasi free nucleon in Deuterium.
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  • A cellular neural network based system for cell counting in culture of biological cells

    Bertucco, L.   Nunnari, G.   Randieri, C.   Rizza, V.   Sacco, A.  

    Cell counting methods are important tools in molecular biology as well as clinical medicine. It is not always technically possible to measure quantitatively the events of cellular growth and fission. When it can be done, the procedures are neither so simple nor without excessive tedium as to lend themselves practically to the necessary replication of observations with large number of individual cells. We describe a CNN based system that uses a CNN simulator for counting cells. The performances of the proposed system are illustrated by a simple cell counting experiment using a Petroff-Hauser based counter system
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  • First measurement of the Sigma beam asymmetry in eta ' photoproduction off the proton near threshold

    Sandri, P. Levi   Mandaglio, G.   De Leo, V.   Bartalini, O.   Bellini, V.   Bocquet, J. -P.   Capogni, M.   Curciarello, F.   Didelez, J. -P.   D'Angelo, A.   Di Salvo, R.   Fantini, A.   Franco, D.   Gervino, G.   Ghio, F.   Girolami, B.   Giusa, A.   Lapik, A.   Lleres, A.   Mammoliti, F.   Manganaro, M.   Moricciani, D.   Mushkarenkov, A.   Nedorezov, V.   Randieri, C.   Rebreyend, D.   Rudnev, N.   Russo, G.   Schaerf, C.   Sperduto, M. -L.   Sutera, M. -C.   Turinge, A.   Vegna, V.   Zonta, I.  

    The Sigma beam asymmetry in eta' photoproduction off the proton was measured at the GrAAL polarised photon beam with incoming photon energies of 1.461 and 1.480 GeV. For both energies the asymmetry as a function of the meson production angle shows a clear structure, more pronounced at the lowest one, with a change of sign around 90 degrees. The observed behaviour is compatible with P-wave D-wave (or S-wave F-wave) interference, the closer to threshold the stronger. The results are compared to the existing state-of-the-art calculations that fail to account for the data.
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  • 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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  • Double pi(0) photoproduction on the neutron at GRAAL RID B-1239-2012

    Ajaka, J.   Assafiri, Y.   Bartalini, O.   Bellini, V.   Bouchigny, S.   Castoldi, M.   D'Angelo, A.   Didelez, J. P.   Di Salvo, R.   Fantini, A.   Fichen, L.   Gervino, G.   Ghio, F.   Girolami, B.   Giusa, A.   Guidal, M.   Hourany, E.   Kunne, R.   Lapik, A.   Sandri, P. Levi   Moricciani, D.   Mushkarenkov, A.   Nedorezov, V.   Randieri, C.   Rudnev, N.   Russo, G.   Schaerf, C.   Sperduto, M.   Sutera, M.   Turinge, A.  

    The photoproduction of double pi(0) on the neutron is studied in the beam energy range of 0.6 up to 1.5 GeV, using a liquid deuterium target. The cross section and the beam asymmetry are extracted and compared to those previously obtained on a proton target. The theoretical interpretation of these results is given using different models. (c) 2007 Elsevier B.V. All rights reserved.
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