-
R. Di Salvo,
A. Fantini,
G. Mandaglio,
F. Mammoliti,
O. Bartalini,
V. Bellini,
J. P. Bocquet,
L. Casano,
A. D’angelo,
J. P. Didelez, [......],
N. Rudnev,
G. Russo,
C. Schaerf,
M. L. Sperduto,
M. C. Sutera, A. Turinge,
V. Vegna,
A. Fix,
S. S. Kamalov,
L. Tiator
[show abstract]
[hide abstract]
ABSTRACT: The S \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 1.50GeV, 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 0.82GeV and substantially different at higher energies. The results are compared with recent
partial-wave analyses.
European Physical Journal A 04/2012; 42(2):151-157. · 2.19 Impact Factor
-
G. Mandaglio,
F. Mammoliti,
M. Manganaro,
V. Bellini,
J. -P. Bocquet,
L. Casano,
A. D'Angelo,
R. Di Salvo,
A. Fantini,
D. Franco, [......],
D. Rebreyend,
N.V. Rudnev,
G Russo,
C. Schaerf,
M. L. Sperduto,
M. -C. Sutera, A. Turinge,
V. Vegna,
W. J. Briscoe,
I. I. Strakovsky
[show abstract]
[hide abstract]
ABSTRACT: The $\Sigma$ beam asymmetry in the photoproduction of negative pions from
quasi-free neutrons in a deuterium target was measured at Graal in the energy
interval 700 - 1500 MeV and a wide angular range, using polarized and tagged
photons. The results are compared with recent partial wave analyses.
Physical Review C 10/2010; 82:045209. · 3.31 Impact Factor
-
J-P Bocquet,
D Moricciani,
V Bellini,
M Beretta,
L Casano,
A D'Angelo,
R Di Salvo,
A Fantini,
D Franco,
G Gervino, [......],
C Perrin,
C Randieri,
D Rebreyend,
N Rudnev,
G Russo,
C Schaerf,
M L Sperduto,
M C Sutera, A Turinge,
V Vegna
[show abstract]
[hide abstract]
ABSTRACT: The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the two-sided limit of 1.6×10(-14) at 95% confidence level on a combination of the parity-violating photon and electron coefficients (κ(o+))(YZ), (κ(o+))(ZX), c(TX), and c(TY). This new constraint provides an improvement over previous bounds by 1 order of magnitude.
Physical Review Letters 06/2010; 104(24):241601. · 7.37 Impact Factor
-
G. MANDAGLIO,
V. BELLINI,
J. P. BOCQUET,
L. CASANO,
A. D'ANGELO,
R. DI SALVO,
A. FANTINI,
D. FRANCO,
G. GERVINO,
F. GHIO, [......],
V. G. NEDOREZOV,
C. RANDIERI,
D. REBREYEND,
N. V. RUDNEV,
G. RUSSO,
C. SCHAERF,
M. L. SPERDUTO,
M. C. SUTERA, A. TURINGE,
V. VEGNA
[show abstract]
[hide abstract]
ABSTRACT: We present the analysis of data performed in order to identify the events of the γ + n → π- + p reaction obtained by bombarding a liquid Deuterium target with a polarised γ 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 Σ of the π- fotoproduction off quasi-free neutron up to about θc.m., π- = 165° together with some theoretical multipolar analysis. For a comparison we also report the data present in literature on the same reaction for Eγ =850-1740 MeV and θc.m., π- ≤105°.
International Journal of Modern Physics E 06/2010; 19(05n06):957. · 0.60 Impact Factor
-
V. G. Gurzadyan,
V. Bellini,
M. Beretta,
J. -P. Bocquet,
A. D'Angelo,
R. Di Salvo,
A. Fantini,
D. Franco,
G. Gervino,
G. Giardina, [......],
D. Moricciani,
V. Nedorezov,
D. Rebreyend,
G. Russo,
N. Rudnev,
C. Schaerf,
M. -L. Sperduto,
M. -C. Sutera, A. Turinge,
V. Vegna
[show abstract]
[hide abstract]
ABSTRACT: When the electrons stored in the ring of the European Synchrotron Radiation
Facility (ESRF, Grenoble) scatter on a laser beam (Compton scattering in
flight) the lower energy of the scattered electron spectra, the Compton Edge
(CE), is given by the two body photon-electron relativistic kinematics and
depends on the velocity of light. A precision measurement of the position of
this CE as a function of the daily variations of the direction of the electron
beam in an absolute reference frame provides a one-way test of Relativistic
Kinematics and the isotropy of the velocity of light. The results of GRAAL-ESRF
measurements improve the previously existing one-way limits, thus showing the
efficiency of this method and the interest of further studies in this
direction.
04/2010;
-
V. VEGNA,
V. BELLINI,
J. P. BOCQUET,
L. CASANO,
A. D’ANGELO,
R. DI SALVO,
A. FANTINI,
D. FRANCO,
G. GERVINO,
F. GHIO, [......],
A. N. MUSHKARENKOv,
V. G. NEDOREZOV,
C. RANDIERI,
D. REBREYEND,
N. V. RUDNEV,
G. RUSSO,
C. SCHAERF,
M. L. SPERDUTO,
M. C. SUTERA, A. TURINGE
[show abstract]
[hide abstract]
ABSTRACT: 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 Σ beam
asymmetry for ω 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 ω 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
P13(1720) state. The analysis performed for the radiative decay is applied to the process
of ω photoproduction on the quasi free nucleon in Deuterium.
International Journal of Modern Physics E 03/2010; 19(5&6):1241. · 0.60 Impact Factor
-
V. Vegna,
V. Bellini,
J. P. Bouquet,
L. Casano,
A. D'Angelo,
J. P. Didelez,
R. Di Salvo,
A. Fantini,
D. Franco,
G. Gervino, [......],
A. N. Mushkarenkov,
V. G. Nedorezov,
C. Randieri,
D. Rebreyend,
N. V. Rudnev,
G. Russo,
C. Schaerf,
M. L. Sperduto,
M. C. Sutera, A. Turinge
[show abstract]
[hide abstract]
ABSTRACT: The GRAAL experimental set-up consists of a polarized and tagged photon beam that covers an energy range from a minimum of 600 MeV up to a maximum of 1500 MeV, of a liquid Hydrogen or Deuterium target and of the 4π Lagrange detector optimized for photon detection. It allows the study of pseudo-scalar and vector meson photoproduction on the nucleon in the energy range corresponding to the second and the third resonance regions. In the following, the σ beam asymmetries in η and π0 photoproduction on quasi-free nucleon are shown. Also single and double polarization observables in K+Λ photoproduction on free proton are shown; they are important to confirm the role of new or poorly known resonances in the 1900 MeV mass region.
Chinese Physics C 01/2010; 33(12):1249. · 0.27 Impact Factor
-
G Mandaglio,
F Mammoliti,
M Manganaro,
V Bellini,
J P Bocquet,
L Casano,
A D'Angelo,
R Salvo,
A Fantini,
D Franco, [......],
D Rebreyend,
N V Rudnev,
G Russo,
C Schaerf,
M L Sperduto,
M C Sutera, A Turinge,
V Vegna,
W J Briscoe,
I I Strakovsky
Physical Review C - Nuclear Physics. 01/2010; 82(4).
-
A Mushkarenkov,
V Bellini,
J P Bocquet,
L Casano,
A D'Angelo,
R Di Salvo,
A Fantini,
D Franco,
G Gervino,
F Ghio, [......],
V Nedorezov,
C Randieri,
D Rebreyend,
N Rudnev,
G Russo,
C Schaerf,
M L Sperduto,
M C Sutera, A Turinge,
V Vegna
International Journal of Modern Physics E. 01/2010; 19(5-6):1197-1204.
-
A. Lleres,
O. Bartalini,
V. Bellini,
J.P. Bocquet,
P. Calvat,
M. Capogni,
L. Casano,
M. Castoldi,
A. D’Angelo,
J.-P. Didelez, [......],
D. Rebreyend,
F. Renard,
N. Rudnev,
T. Russew,
G. Russo,
C. Schaerf,
M.-L. Sperduto,
M.-C. Sutera, A. Turinge,
V. Vegna
[show abstract]
[hide abstract]
ABSTRACT: The double polarization (beam-recoil) observables Ox and Oz have been measured for the reac-
tion γp → K+Λ from threshold production to E ∼ 1500MeV. 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 1900MeV mass region.
European Physical Journal A 09/2009; 39:149. · 2.19 Impact Factor
-
The GRAAL Collaboration,
A. Lleres,
O. Bartalini,
V. Bellini,
J. P. Bocquet,
P. Calvat,
M. Capogni,
L. Casano,
M. Castoldi,
A. D’Angelo, [......],
D. Rebreyend,
F. Renard,
N. Rudnev,
T. Russew,
G. Russo,
C. Schaerf,
M. -L. Sperduto,
M. -C. Sutera, A. Turinge,
V. Vegna
[show abstract]
[hide abstract]
ABSTRACT: The double polarization (beam-recoil) observables Ox\ensuremath O_x and Oz\ensuremath O_z have been measured for the reaction g \gamma
p → K
+
L \Lambda from threshold production to Eg ~ 1500\ensuremath E_{\gamma} \sim 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 1900MeV mass region.
European Physical Journal A 01/2009; 39(2):149-161. · 2.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Total (atomic+nuclear) photoabsorption cross section of $^{52}Cr$ was for the first time measured in the energy range of 8-70 MeV. Experimental data was produced with small statistic and systematic errors. The results deviate from calculations of atomic cross section at photon energies above 40 MeV. Photonuclear cross section in the region of the E1 giant dipole resonance (GDR) clearly exhibits three peaks at 18.9, 20.9 and 23.1 MeV. At higher energies, the measured cross section hints a dip-peak structure at 40-48 MeV.
01/2009;
-
A. Lleres,
O. Bartalini,
JP. Bocquet,
P. Calvat,
M. Capogni,
L. Casano,
A. D'Angelo,
JP Didelez,
R. DiSalvo,
A. Fantini, [......],
C. Randieri,
D. Rebreyend,
F. Renard,
N. Rudnev,
T. Russew,
G Russo,
C. Schaerf,
ML. Sperduto,
MC. Sutera, A. Turinge
[show abstract]
[hide abstract]
ABSTRACT: The double polarization (beam-recoil) observables Ox and Oz have been measured for the reaction gamma p -> K Lambda from threshold production to Egamma = 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. Comment: 19 pages, 15 figures, 3 tables
07/2008;
-
A Fantini,
R Di Salvo,
O Bartalini,
V Bellini,
J P Bocquet,
L Casano,
M Castoldi,
A D'Angelo,
D Franco,
G Gervino, [......],
N Rudnev,
G Russo,
C Schaerf,
M -L Sperduto,
M -C Sutera, A Turinge,
V Vegna,
A Fix,
L Tiator,
S Kamalov
[show abstract]
[hide abstract]
ABSTRACT: We present the first measurement of the � beam asymmetry in η photoproduction on the neutron in the photon energy range from threshold to 1.5 GeV. Data have been collected by using the tagged and linearly polarized photon beam and the large solid angle apparatus of the GRAAL facility. Neutron data have been selected among η photoproduction events on the deuteron in the quasi-free kinematics approximation. Proton data, extracted in the same way, are within errors identical to those previously obtained on free protons at the GRAAL facility, except for a few points falling in certain energy bins. This difference is, however, well understood in terms of the Fermi motion of the nucleons in the deuteron. We take the consistency of free and quasi-free proton data as an indication that nuclear effects are negligible also for neutron data. The ETAMAID model, in which a strong coupling of the D15(1675) resonance to the η-neutron channel is introduced, can explain the proton data very well, but it cannot describe the beam asymmetry for the neutron.
Physical Review C 07/2008; 78(1):015203. · 3.31 Impact Factor
-
J Ajaka,
Y Assafiri,
O Bartalini,
V Bellini,
S Bouchigny,
M Castoldi,
A D'Angelo,
J P Didelez,
R Di Salvo,
M Döring, [......],
A Mushkarenkov,
V Nedorezov,
E Oset,
C Randieri,
N Rudnev,
G Russo,
C Schaerf,
M Sperduto,
M Sutera, A Turinge
[show abstract]
[hide abstract]
ABSTRACT: The analysis of the gammap-->etapi(0)p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S11(1535) and Delta(1700) are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the Delta(1700) excitation, followed by the decay into etaDelta(1232), is found to be dominant.
Physical Review Letters 02/2008; 100(5):052003. · 7.37 Impact Factor
-
J Ajaka,
Y Assafiri,
O Bartalini,
V Bellini,
S Bouchigny,
M Castoldi,
A D'Angelo,
J P Didelez,
R Di Salvo,
M Döring, [......],
A Mushkarenkov,
V Nedorezov,
E Oset,
C Randieri,
N Rudnev,
G Russo,
C Schaerf,
M Sperduto,
M Sutera, A Turinge
Physical Review Letters 01/2008; 100(5). · 7.37 Impact Factor
-
A Fantini,
R Di Salvo,
O Bartalini,
V Bellini,
J P Bocquet,
L Casano,
M Castoldi,
A D'angelo,
D Franco,
G Gervino, [......],
N Rudnev,
G Russo,
C Schaerf,
M -L Sperduto,
M -C Sutera, A Turinge,
V Vegna,
A Fix,
L Tiator,
S Kamalov
Physical Review C - Nuclear Physics. 01/2008; 78(1).
-
O. Bartalini,
V. Bellini,
J. -P. Bocquet,
P. Calvat,
M. Capogni,
L. Casano,
M. Castoldi,
A. D'Angelo,
J. -P. Didelez,
R. Di Salvo, [......],
D. Rebreyend,
F. Renard,
N. Rudnev,
T. Russew,
G Russo,
C. Schaerf,
M. L. Sperduto,
M. -C. Sutera, A. Turinge,
V. Vegna
[show abstract]
[hide abstract]
ABSTRACT: Beam asymmetry and differential cross section for the reaction gamma+p->eta+p were measured from production threshold to 1500 MeV photon laboratory energy. The two dominant neutral decay modes of the eta meson, eta->2g and eta->3pi0, 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.
08/2007;
-
A. D’Angelo,
O. Bartalini,
V. Bellini,
J. P. Bocquet,
P. Calvat,
M. Capogni,
L. Casano,
M. Castoldi,
J. -P. Didelez,
R. Di Salvo, [......],
D. Rebreyend,
F. Renard,
N. Rudnev,
T. Russew,
G. Russo,
C. Schaerf,
M. -L. Sperduto,
M. -C. Sutera, A. Turinge,
V. Vegna
[show abstract]
[hide abstract]
ABSTRACT: Meson photoproduction with polarized photons has proved to be a powerful tool to identify contributions of baryon resonances that are not evident in the differential cross-sections. It provides information that are complementary to those extracted using pion-nucleon scattering data. Extensive results have been produced in the past on beam asymmetries by the Graal collaboration
for η and π
0 on the proton. New results are now available for the same reactions on the quasi-free neutron and for the K + photoproduction on the proton. Contributions from hitherto undetected baryon resonances may be important to understand the
results.
European Physical Journal A 03/2007; 31(4):441. · 2.19 Impact Factor
-
The GRAAL Collaboration,
O. Bartalini,
V. Bellini,
J. P. Bocquet,
P. Calvat,
M. Capogni,
L. Casano,
M. Castoldi,
A. D'Angelo,
J. -P. Didelez, [......],
D. Rebreyend,
F. Renard,
N. Rudnev,
T. Russew,
G. Russo,
C. Schaerf,
M. -L. Sperduto,
M. -C. Sutera, A. Turinge,
V. Vegna
[show abstract]
[hide abstract]
ABSTRACT: Beam asymmetry and differential cross-section for the reaction γp → ηp were measured from production threshold to 1500MeV photon laboratory energy. The two dominant neutral decay modes of the
η -meson, η → 2γ and η → 3π0 , 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.
European Physical Journal A 01/2007; 33(2):169-184. · 2.19 Impact Factor
