K. Ullaland

The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events

The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m(3) and is operated in a 0.5T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb-Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at root S-NN=2.76 TeV

Article history: Received 28 May 2012 Received in revised form 28 November 2012 Accepted 28 December 2012 Available online 4 January 2013 Editor: V. Metag The elliptic, v2, triangular, v3, and quadrangular, v4, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions, and (anti-)protons in Pb–Pb collisions at √ sNN = 2.76 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 |η| < 0.8 at different collision centralities and as a function of transverse momentum, pT, out to pT = 20 GeV/c. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for pT > 8 GeV/c. The small pT dependence of the difference between elliptic flow results obtained from the event plane and fourparticle cumulant methods suggests a common origin of flow fluctuations up to pT = 8 GeV/c. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least pT = 8 GeV/c indicating that the particle type dependence persists out to high pT.

J/Ψ production and nuclear effects in p-Pb collisions at √sNN=5.02 TeV

Inclusive J/psi production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy = 5.02 TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < y (cms) < 3.53 and -4.46 < y (cms) < -2.96, down to zero transverse momentum, studying the mu (+) mu (-) decay mode. In this paper, the J/psi production cross section and the nuclear modification factor R (pPb) for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/psi yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.A bstractInclusive J/ψ production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy

Charmonium and e(+)e(-) pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at root s(NN)=2.76 TeV

\sqrt{{{s_{\mathrm{NN}}}}}

Particle-Yield Modification in Jetlike Azimuthal Dihadron Correlations in Pb-Pb Collisions at root S-NN=2.76 TeV

= 5.02 TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < ycms< 3.53 and −4.46 < ycms< −2.96, down to zero transverse momentum, studying the μ+μ− decay mode. In this paper, the J/ψ production cross section and the nuclear modification factor RpPb for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/ψ yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.

Measurement of charged jet suppression in Pb-Pb collisions at √s NN = 2.76 TeV

The ALICE Collaboration at the LHC has measured the J/ψ and ψ′ photoproduction at mid-rapidity in ultra-peripheral Pb–Pb collisions at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}

Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV

\sqrt{s_{\mathrm{NN}}}=2.76~\mathrm{TeV}

K*(892)(0) and phi(1020) production in Pb-Pb collisions at root s(NN)=2.76 TeV

\end{document}. The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 μb−1. The cross section for coherent and incoherent J/ψ production in the rapidity interval −0.9<y<0.9, are \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}

Production of light nuclei and anti-nuclei in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

\mathrm{d}\sigma_{\mathrm{J}/\psi}^{\mathrm{coh}}/\mathrm{d}y = 2.38^{+0.34}_{-0.24} (\mathrm{sta+sys} )~\mathrm{mb}

Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions

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