226 research outputs found
Identification of the K*± resonance decay by topological cuts and multivariate discrimination methods
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Identification of the K*± resonance decay by topological cuts and multivariate discrimination methods
Performance of ALICE pixel prototypes in high energy beams
The two innermost layers of the ALICE inner tracking system are instrumented
with silicon pixel detectors. Single chip assembly prototypes of the ALICE
pixels have been tested in high energy particle beams at the CERN SPS.
Detection efficiency and spatial precision have been studied as a function of
the threshold and the track incidence angle. The experimental method, data
analysis and main results are presented.Comment: 10 pages, 9 figures, contribution to PIX2005 Workshop, Bonn
(Germany), 5-8 September 200
Beam Test Performance and Simulation of Prototypes for the ALICE Silicon Pixel Detector
The silicon pixel detector (SPD) of the ALICE experiment in preparation at
the Large Hadron Collider (LHC) at CERN is designed to provide the precise
vertex reconstruction needed for measuring heavy flavor production in heavy ion
collisions at very high energies and high multiplicity. The SPD forms the
innermost part of the Inner Tracking System (ITS) which also includes silicon
drift and silicon strip detectors. Single assembly prototypes of the ALICE SPD
have been tested at the CERN SPS using high energy proton/pion beams in 2002
and 2003. We report on the experimental determination of the spatial precision.
We also report on the first combined beam test with prototypes of the other ITS
silicon detector technologies at the CERN SPS in November 2004. The issue of
SPD simulation is briefly discussed.Comment: 4 pages, 5 figures, prepared for proceedings of 7th International
Position Sensitive Detectors Conference, Liverpool, Sept. 200
New results from the NA57 experiment
We report results from the experiment NA57 at CERN SPS on hyperon production
at midrapidity in Pb-Pb collisions at 158 GeV/ and 40 GeV/.
, and yields are compared with those from the STAR
experiment at the higher energy of the BNL RHIC. , , \
and preliminary transverse mass spectra are presented and interpreted
within the framework of a hydro-dynamical blast wave model.Comment: 8 pages, 3 figures, contribution to the proceedings of The XXXVIIIth
Rencontres de Moriond "QCD and High Energy Hadronic Interactions
Expansion dynamics of Pb-Pb collisions at 40 A GeV/c viewed by negatively charged hadrons
In this paper we present results on transverse mass spectra and Hanbury-Brown
and Twiss correlation functions of negatively charged hadrons, which are
expected to be mostly negative pions, measured in Pb-Pb collisions at 40 A
GeV/c beam momentum. Based on these data, the collision dynamics and the
space-time extent of the system at the thermal freeze-out are studied over a
centrality range corresponding to the most central 53% of the Pb--Pb inelastic
cross section. Comparisons with freeze-out conditions of strange particles and
HBT results from other experiments are discussed.Comment: 29 pages, 18 figure
Results on hyperon production from the NA57 experiment
Recent results on hyperon production in Pb--Pb collisions from the NA57
experiment are reported. Strangeness enhancement and the transverse mass
spectra properties at 158 GeV per nucleon are described.Comment: submitted to Acta Phys. Hung. A (Heavy Ion Physics
Strange particle production in 158 and 40 GeV/ Pb-Pb and p-Be collisions
Results on strange particle production in Pb-Pb collisions at 158 and 40
GeV/ beam momentum from the NA57 experiment at CERN SPS are presented.
Particle yields and ratios are compared with those measured at RHIC.
Strangeness enhancements with respect to p-Be reactions at the same beam
momenta have been also measured: results about their dependence on centrality
and collision energy are reported and discussed.Comment: Contribution to the proceedings of the "Hot Quarks 2004" Conference,
July 18-24 2004, New Mexico, USA, submitted to Journal of Physics G 7 pages,
5 figure
Performance of prototypes for the ALICE electromagnetic calorimeter
The performance of prototypes for the ALICE electromagnetic sampling
calorimeter has been studied in test beam measurements at FNAL and CERN. A
array of final design modules showed an energy resolution of about
11% / 1.7 % with a uniformity of the response
to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV.
The electromagnetic shower position resolution was found to be described by 1.5
mm 5.3 mm /. For an electron identification
efficiency of 90% a hadron rejection factor of was obtained.Comment: 10 pages, 10 figure
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
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