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.
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.
Manganaro, M.
Bellini, V.
Bocquet, J. P.
Casano, L.
D'Angelo, A.
Di Salvo, R.
Fantini, A.
Franco, D.
Gervino, G.
Ghio, F.
Giardina, G.
Giusa, A.
Girolami, B.
Ignatov, A. S.
Lapik, A. M.
Sandri, P. Levi
Lleres, A.
Mammoliti, F.
Mandaglio, G.
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.
The gamma p -> eta'p reaction was studied near the threshold, in the 1.44 GeV > E(gamma) < 1.55GeV energy range with the tagged photons of the former GRAAL experiment. The two neutral decays gamma gamma(Gamma(i)/Gamma = 2.10 +/- 0.12%) and pi(0)pi(0)eta(Gamma(i)/Gamma = 20.7 +/- 1.2%) were analized and preliminary results of the beam asymmetry were extracted together with the invariant masses.
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.
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.
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.
A multi-workstation for use in a work area of a garage having a vertically oriented pole with an upper end and a lower end and a light fixture mounted between the upper end and the lower end of the vertically oriented pole. The light fixture is capable of sliding up and down along the pole, rotating about an axis that is perpendicular to the axis of the pole, moving horizontally toward and away from the pole, and rotating about an axis that is perpendicular to the axis of the pole. Locking means is provided to lock the light fixture at a desired height and angle relative to the pole and mounting means is provided to hold the pole in a vertical position.
Significant enhancements of J/psi production at very low transverse momenta were recently observed by the ALICE and STAR collaborations in peripheral hadronic A+A collisions. The anomalous excess points to coherent photon-nucleus interactions in violent hadronic heavy-ion collisions, which were conventionally studied only in ultra-peripheral collisions. Assuming that the coherent photoproduction is the underlying mechanism responsible for the excess observed in peripheral A+A collisions, its contribution in p+p collisions with nuclear overlap, i.e. nonsingle-diffractive collisions, is of particular interest. In this paper, we perform a calculation of exclusive J/psi photoproduction in non-single-diffractive p+p collisions at the RHIC and LHC energies based on the pQCD motivated parametrization using the world-wide experimental data, which could be further employed to improve the precision of the phenomenological calculations for photoproduction in A+A collisions. The differential rapidity and transverse momentum distributions of J/psi from photoproduction are presented. In comparison with the J/psi production from hadronic interactions, we find that the contribution of photoproduction is negligible.
Let p(1),..., p(n) be positive real numbers. It is well known that for every r < 0 the matrix [(p(i) + p(j))(r)] is positive definite. Our main theorem gives a count of the number of positive and negative eigenvalues of this matrix when r > 0. Connections with some other matrices that arise in Loewner's theory of operator monotone functions and in the theory of spline interpolation are discussed.
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