759 research outputs found
Physics with the ALICE experiment
ALICE experiment at LHC collects data in pp collisions at =0.9,
2.76 and 7 TeV and in PbPb collisions at 2.76 TeV. Highlights of the detector
performance and an overview of experimental results measured with ALICE in pp
and AA collisions are presented in this paper. Physics with proton-proton
collisions is focused on hadron spectroscopy at low and moderate .
Measurements with lead-lead collisions are shown in comparison with those in pp
collisions, and the properties of hot quark matter are discussed.Comment: Presented at the Conference of the Nuclear Physics Division of the
Russian Academy of Science, 11-25.11.2011, ITEP, Moscow. 16 pages, 14 figure
Multi-strange baryon elliptic flow in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV measured with the ALICE detector
We present the results on elliptic flow with multi-strange baryons produced
in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV. The analysis is performed with
the ALICE detector at LHC. Multi-strange baryons are reconstructed via their
decay topologies and the v_2 values are analyzed with the two-particle scalar
product method. The p_T differential v_2 values are compared to the VISH2+1
model calculation and to the STAR measurements at 200 GeV in Au+Au collisions.
We found that the model describes \Xi and \Omega v_2 measurements within
experimental uncertainties. The differential flow of \Xi and \Omega is similar
to the STAR measurements at 200 GeV in Au+Au collisions.Comment: Prepared for the Proceedings of the International Conference on
"Critical Point and Onset of Deconfinement - CPOD 2011", Wuhan, November
7-11, 201
Cross section normalization in proton-proton collisions at = 2.76 TeV and 7 TeV, with ALICE at LHC
Measurements of the cross sections of the reference processes seen by the
ALICE trigger system were obtained based on beam properties measured from van
der Meer scans. The measurements are essential for absolute cross section
determinations of physics processes.
The paper focuses on instrumental and technical aspects of detectors and
accelerators, including a description of the extraction of beam properties from
the van der Meer scan. As a result, cross sections of reference processes seen
by the ALICE trigger system are given for proton-proton collisions at two
energies; =2.76 TeV and 7 TeV, together with systematic uncertainties
originating from beam intensity measurements and other detector effects.
Consistency checks were performed by comparing to data from other experiments
in LHC.Comment: Quark Matter 2011 Conference Proceedings, 4 pages, 2 figure
Correlations and fluctuations studied with ALICE
The measurement of particle correlations and event-by-event fluctuations of
physical observables allows to study a large variety of properties of the
matter produced in ultra relativistic heavy-ion collisions. We will present
results for two-particle correlations, mean transverse momentum fluctuations,
and net charge fluctuations in Pb-Pb collisions at 2.76 TeV.Comment: 7 pages, 5 figures, Proceedings submitted for the 28th Winter
Workshop on Nuclear Dynamics, Puerto Rico, April 7-14, 2012; corrected typo
First Results from Pb+Pb collisions at the LHC
At the end of 2010, the CERN Large Hadron Collider started operation with
heavy ion beams, colliding lead nuclei at a centre-of-mass energy of 2.76
TeV/nucleon and opening a new era in ultra-relativistic heavy ion physics at
energies exceeding previous accelerators by more than an order of magnitude.
This review summarizes the results from the first year of heavy ion physics at
LHC obtained by the three experiments participating in the heavy ion program,
ALICE, ATLAS, and CMS.Comment: To appear in Annual Review of Nuclear and Particle Scienc
Suppression of neutral pion production at large transverse momentum measured with the ALICE experiment in Pb-Pb collisions at TeV
The ALICE collaboration at the LHC has measured the transverse momentum
spectra of neutral pions via their two photon decay in pp and PbPb
collisions at TeV over a broad transverse momentum range
with different subsystems: with the electromagnetic calorimeters PHOS and EMCAL
and with photon conversions in the inner material of the detectors using
pairs reconstructed with the Central Tracking System. In this
report, neutral pions production is compared between pp and PbPb collisions
measured with conversion photons in terms of the nuclear modification factor,
, for different centrality selections of the PbPb data sample.Comment: 4 pages, 4 figures, proceedings of QM 201
Heavy Ions: Results from the Large Hadron Collider
On November 8, 2010 the Large Hadron Collider (LHC) at CERN collided first
stable beams of heavy ions (Pb on Pb) at center-of-mass energy of 2.76
TeV/nucleon. The LHC worked exceedingly well during its one month of operation
with heavy ions, delivering about 10 microbarn-inverse of data, with peak
luminosity reaching to
towards the end of the run. Three experiments, ALICE, ATLAS and CMS, recorded
their first heavy ion data, which were analyzed in a record time. The results
of the multiplicity, flow, fluctuations, and Bose-Einstein correlations
indicate that the fireball formed in nuclear collisions at the LHC is hotter,
lives longer, and expands to a larger size at freeze-out as compared to lower
energies. We give an overview of these as well as new results on quarkonia and
heavy flavour suppression, and jet energy loss.Comment: Proceedings of Lepton-Photon 2011 Conference, to be published in
Pramana, Journal of Physics. 15 page
VISHNU hybrid model for viscous QCD matter at RHIC and LHC energies
In this proceeding, we briefly describe the viscous hydrodynamics + hadron
cascade hybrid model VISHNU for relativistic heavy ion collisions and report
the current status on extracting the QGP viscosity from elliptic flow data.Comment: 4 pages, 1 figure, the proceedings of 7th International Workshop on
Critical Point and Onset of Deconfinement, Wuhan, China, Nov. 7-11, 201
The PreAmplifier ShAper for the ALICE TPC-Detector
In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber
(TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an
ASIC that integrates 16 identical channels, each consisting of Charge Sensitive
Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network,
two second-order bridged-T filters, two non-inverting level shifters and a
start-up circuit. The circuit is optimized for a detector capacitance of 18-25
pF. For an input capacitance of 25 pF, the PASA features a conversion gain of
12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of
11.65 mW/ch and an equivalent noise charge of 244e + 17e/pF. The circuit
recovers smoothly to the baseline in about 600 ns. An integral non-linearity of
0.19% with an output swing of about 2.1 V is also achieved. The total area of
the chip is 18 mm and is implemented in AMS's C35B3C1 0.35 micron CMOS
technology. Detailed characterization test were performed on about 48000 PASA
circuits before mounting them on the ALICE TPC front-end cards. After more than
two years of operation of the ALICE TPC with p-p and Pb-Pb collisions, the PASA
has demonstrated to fulfill all requirements
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