The “standard” Hall A apparatus at Jefferson Lab (TOF and aerogel threshold Cherenkov detectors) does not provide complete identification for proton, kaon and pion. To this aim, a proximity focusing ...C
6F
14/CsI RICH (Ring Image CHerenkov) detector has been designed, built, tested and operated to separate kaons from pions with a pion contamination of a few percent up to 2.4
GeV/
c. Two quite different experimental investigations have benefitted of the RICH identification: on one side, the high-resolution hypernuclear spectroscopy series of experiments on carbon, beryllium and oxygen, devoted to the study of the lambda-nucleon potential. On the other side, the measurements of the single spin asymmetries of pion and kaon on a transversely polarized
3He target are of utmost interest in understanding QCD dynamics in the nucleon. We present the technical features of such a RICH detector and comment on the presently achieved performance in hadron identification.
Prototype of a dual-radiator RICH detector for the Electron–Ion Collider Vallarino, S.; Alexeev, M.; Antonioli, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2024, Letnik:
1058, Številka:
C
Journal Article
Nucleon form factor studies at JLab Giusa, A.; Bellini, V.; Mammoliti, F. ...
Applied radiation and isotopes,
08/2011, Letnik:
69, Številka:
8
Journal Article
Recenzirano
The ratio of the electromagnetic proton elastic form factors,
G
p
E
/
G
p
M
, has been measured at Jefferson Lab up to
Q
2
≈
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
p
E
/
G
p
M
up to
Q
2
≈
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.
Differential and total cross section measurements on η′ photoproduction were published by the CLAS Collaboration (M. Dugger et al., Phys.Rev.Lett.96, 062001 (2006) and M. Williams et al., ...Phys.Rev.C80, 045213 (2009)) for center-of-mass energies from near the threshold up to 2.84 GeV, and by the CB-ELSA-TAPS Collaboration (V. Crede et al., Phys.Rev.C80, 055202 (2009)) up to 2.36 GeV and also making a precise threshold scan of the differential cross section in the 1446 – 1527.4 MeV γ beam energy range. However, the wide information about reaction cross sections are not sufficient to understand the role of resonances involved in the process. Different theoretical works stressed the importance to have also polarization observables in order to solve the ambiguity in the choice of the parameters used in their models. We present the analysis of the η′ photoproduction off the proton, identifying the meson via the γγ, π0π0η, and π+π−η decay modes by using the GRAAL apparatus; and we show the preliminary GRAAL results on the beam asymmetry Σ from the threshold (1.446 GeV) up to 1.5 GeV.
The only recent η′ photoproduction data off proton available in literature are the differential and total cross sections published by the CLAS and CB-ELSA-TAPS Collaborations. However, the wide ...information about reaction cross sections are not sufficient to understand the role of resonances involved in the process. Different theoretical works stressed the importance to measure also polarization observables in order to solve the ambiguities in the choice of the parameters used in their models. We present the analysis of η′ photoproduction off the proton analysis, identifying the investigated meson by the π+π−η, π0π0η, and γγ decay modes by using the GRAAL apparatus; and we show the preliminary GRAAL results on the beam asymmetry Σ at beam energy of 1475 MeV.
Compact solid-state detectors based on CVD single-crystal diamonds (SCD), configured in a p-type/intrinsic/Schottky-metal layered structure, are proposed for the detection of high-energy ions at the ...15-MV tandem accelerator of the Southern National Laboratory of INFN in Catania. The spectroscopic response of two thin-film SCD detectors has been studied by varying the angle of incidence of a 27-77 MeV
12
C-scattered ion beam and a simple theoretical model is reported for the fit of the experimental curves of the collected energy vs. the angle of incidence. A rough estimation of the detector sensitive thickness and of the charge collection efficiency has thus been obtained.
Observation of a narrow structure at
W
∼ 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
γ
N
→
...πηN
reactions from GRAAL seems to reveal the signals of both
N
+
(1685) and
N
0
(1685) resonances.
The C49–C54 transformation has been studied in TiSi
2 thin films having different concentration of defects. The defect concentration in the C49 phase has been varied using different thermal processes ...in the 460–540
°C temperature range; in fact, the defect concentration decreases with increasing the temperature and/or the duration of the thermal process as attested by the large variation of the silicide residual resistivity at 4 K. The kinetics of the transformation at 650
°C has been followed by in situ resistivity measurements and, for each sample, the transition time decreases as the defect concentration in the metastable phase decreases.
Observation of a narrow structure at W ∼ 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 γN → ...πηN reactions from GRAAL seems to reveal the signals of both N+(1685) and N0(1685) resonances.
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