The ratio of the yields of antiprotons to protons in pp collisions has been measured by the ALICE experiment at sqrt[s]=0.9 and 7 TeV during the initial running periods of the Large Hadron Collider. The measurement covers the transverse momentum interval 0.45

The p t -differential inclusive production cross sections of the prompt charmed mesons D 0 , D + , and D * + in the rapidity range |y| < 0.5 were measured in proton-proton collisions at √ s = 7 TeV at the LHC using the ALICE detector. Reconstructing the decaysand their charge conjugates, about 8,400 D 0 , 2,900 D + , and 2,600 D * + mesons with 1 < p t < 24 GeV/c were counted, after selection cuts, in a data sample of 3.14×10 8 events collected with a minimum-bias trigger (integrated luminosity L int = 5 nb −1 ). The results are described within uncertainties by predictions based on perturbative QCD.

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Centrality dependence of the pseudorapidity density distribution for charged particles in Pb-Pb collisions at √ s NN = 2.76 TeV ✩ .ALICE Collaboration a r t i c l e i n f o a b s t r a c tWe present the first wide-range measurement of the charged-particle pseudorapidity density distribution, for different centralities (the 0-5%, 5-10%, 10-20%, and 20-30% most central events) in Pb-Pb collisions at √ s NN = 2.76 TeV at the LHC. The measurement is performed using the full coverage of the ALICE detectors, −5.0 < η < 5.5, and employing a special analysis technique based on collisions arising from LHC 'satellite' bunches. We present the pseudorapidity density as a function of the number of participating nucleons as well as an extrapolation to the total number of produced charged particles (N ch = 17 165 ± 772 for the 0-5% most central collisions). From the measured dN ch /dη distribution we derive the rapidity density distribution, dN ch /dy, under simple assumptions. The rapidity density distribution is found to be significantly wider than the predictions of the Landau model. We assess the validity of longitudinal scaling by comparing to lower energy results from RHIC. Finally the mechanisms of the underlying particle production are discussed based on a comparison with various theoretical models.ICE detector. The employed method relies on using so-called 'satellite' bunch collisions and is based on measurements from three ✩ © CERN for the benefit of the ALICE Collaboration. different ALICE sub-detectors. This method is applicable for the 30% most central events where the trigger efficiency for these 'satellite' collisions remains high. These measurements extend considerably the former results obtained at the LHC [8-10] and can be compared to the wealth of results on the charged-particle pseudorapidity density from lower energy Au-Au collisions at RHIC [6,11, 12] as well as model calculations. Experimental setupA detailed description of the ALICE detector can be found in [13]. In the following, we will briefly describe the detectors used in this analysis, namely the Silicon Pixel Detector (SPD), the Forward Multiplicity Detector (FMD), the VZERO, and the Zero Degree Calorimeter (ZDC) (see Fig. 1).The SPD is the innermost element of the ALICE inner tracking system [13]. It consists of two cylindrical layers of hybrid silicon pixel assemblies positioned at radial distances of 3.9 and 7.6 cm from the beam line, with a total of 9.8 × 10 6 pixels of size 50 × 425 μm 2 , read out by 1200 electronic chips. The SPD coverage for particles originating from the nominal interaction point at the center of the detector is |η| < 2 and |η| < 1.4 for the inner and outer layers, respectively.The VZERO detector [14] consists of two arrays of 32 scintillator tiles (4 rings of increasing radii each with 8 azimuthal sectors) placed at distances of 3.3 m (VZERO-A) and −0.9 m (VZERO-C) from the nominal interaction point along the beam axis, covering the full azimuth within 2.8 < η < 5.1 and −3.7 < η < −1.7, 0370-2693/

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