Blahoslav Pastircak

CERN-LHC. Measurements of cross sections of inelastic and diffractive processes in proton--proton... more CERN-LHC. Measurements of cross sections of inelastic and diffractive processes in proton--proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass $M_X < 200$ GeV/$c^2$) $\sigma_{\rm SD}/\sigma_{\rm INEL} = 0.21 \pm 0.03, 0.20^{+0.07}_{-0.08}$, and $0.20^{+0.04}_{-0.07}$, respectively at centre-of-mass energies $\sqrt{s} = 0.9, 2.76$, and 7 TeV; for double diffraction (for a pseudorapidity gap $\Delta\eta > 3$) $\sigma_{\rm DD}/\sigma_{\rm INEL} = 0.11 \pm 0.03, 0.12 \pm 0.05$, and $0.12^{+0.05}_{-0.04}$, respectively at $\sqrt{s} = 0.9, 2.76$, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: $\sigma_{\rm INEL} = 62.8^{+...

Table 2

CERN-LHC. Measurement of the pT-differential inclusive production cross section of the prompt cha... more CERN-LHC. Measurement of the pT-differential inclusive production cross section of the prompt charm-strange meson D_s^+ in the rapidity range |y| < 0.5. The analysis was performed on a data sample of 2.98*10^8 events collected in 2010 in proton-proton collisions at sqrt(s) = 7 TeV at the LHC using the ALICE detector with a minimum-bias trigger, with a corresponding integrated luminosity of 4.8 nb^-1. The ratios of the cross sections of four D meson species (namely D^0, D^+, D*^+ and D_s^+) are determined both as a function of pT and integrated over pT after extrapolating to the full pT range, together with the strangeness suppression factor in charm fragmentation.

Table 1

CERN-LHC. Measurements of the angular correlations between charged trigger and associated particl... more CERN-LHC. Measurements of the angular correlations between charged trigger and associated particles in proton-Lead collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for trigger and associated particle transverse momentum in the range 0.5 to 4 GeV (with PT_trig>PT-assoc). The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity (multiplicity classes). Two longe-range ridge-like structures, on the near and away sides, are observed when the per-trigger yield observed in low multiplicity events is subtracted from the one in high multilplisity events. The two ridge-like structures, projected on to the azimuthal angle, are quantified with the 2nd and 3rd Fourier coefficients as well as by near-side and away-side yields and widths.

Table 5

CERN-LHC. Study of the correlations between pairs of charged particles produced in Lead-Lead coll... more CERN-LHC. Study of the correlations between pairs of charged particles produced in Lead-Lead collisions at a nucleon-nucleon centre-of mass energy of 2.76 TeV. The data were collected during the heavy-ion run in 2010 with over 15 million Lead-Lead events being analysed. The data were analysed using the Balance Function which describes the conditional probabilty that a particle in a momentum space P1 will be accompanied (balanced) by a particle of opposite charge and momentum P2. The user is refered to the text of the paper for the exact definition. Data are presented in terms of the relative differences in the pseudorapidities and of the azimuthal angles of the charged particles. In addition, results are given for a mixed data set from all two-particle non-same-event combinations from a few (~5) events with similar values of the z position and the reconstructed vertex and from the same centrality class and similar multiplicities.

Table 2

CERN-LHC. Measurements of the differential PT sepctra for the production of the multi-strange bar... more CERN-LHC. Measurements of the differential PT sepctra for the production of the multi-strange baryons OMEGA- and XI-, and separately their antiparticles, in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, collected during the 2010 running period, contain around 130 million minimum bias events and cover the mid-rapidity region (-0.5-0.5) and the PT ranges 0.6-8.5 GerV/c for XI- baryons and 0.8-5 GeV/c for OMEGA- baryons.

Table 1

CERN-LHC. Measurements of the tranverse sphericity of charged particles in minimum bias events pr... more CERN-LHC. Measurements of the tranverse sphericity of charged particles in minimum bias events produced in proton-proton collisions at centre-of mass energies of 0.9, 2.76 and 7 TeV. The data samples at 0.9 and 7 Tev(recorded in 2010) and at 2.76 (recorded in 2011) have about 4 million events , each at 7 and 2.76 TeV and 3.6 at 0.9 TeV. Mean values of the transverse sphericity and tranverse momentum, in all events and subdivided into soft and hard accordng to the maximum PT of the leading particle, as a function of charged particle multiplicty are presented together with the transverse sphericity distributions in four regions of multiplicity.

Table 4

CERN-LHC. Measurement of the effect of event background fluctuations on charged particle jet reco... more CERN-LHC. Measurement of the effect of event background fluctuations on charged particle jet reconstruction in PB-PB collisions at a centre-of-mass energy of 2.76 TeV/nucleon. Rigid cones with radius R=0.4 are placed in each reconstructed event at random PHI and ETA with their centroid within |ETA|<0.5 and the background fluctuations are characterized by DeltaPT which is the difference of the scalar sum of all track PT in the cone and the expected background. See the text of the paper for more details. Probability densities are presented for different random cone scenarios.

img1. gif, img2. gif and img3. gif production at mid-rapidity in Pb-Pb and p-Pb collisions at 158 A GeV/c

Journal of Physics G Nuclear Physics, 1999

... Affiliation: AA(Fysisk institutt, Universitetet i Bergen, Bergen, Norway ), AB(), AC(Dipartim... more

Table 3

CERN-LHC. This publication describes the methods used to measure the centrality of inelastic Pb-P... more CERN-LHC. This publication describes the methods used to measure the centrality of inelastic Pb-Pb collisions at a center-of-mass energy of 2.76 TeV per colliding nucleon pair with ALICE. The centrality is a key parameter in the study of the properties of QCD matter at extreme temperature and energy density, because it is directly related to the initial overlap region of the colliding nuclei. Geometrical properties of the collision, such as the number of participating nucleons and number of binary nucleon-nucleon collisions, are deduced from a Glauber model with a sharp impact parameter selection, and shown to be consistent with those extracted from the data. The centrality determination provides a tool to compare ALICE measurements with those of other experiments and with theoretical calculations.

Table 7

CERN-LHC. Measurement of the effect of event background fluctuations on charged particle jet reco... more CERN-LHC. Measurement of the effect of event background fluctuations on charged particle jet reconstruction in PB-PB collisions at a centre-of-mass energy of 2.76 TeV/nucleon. Rigid cones with radius R=0.4 are placed in each reconstructed event at random PHI and ETA with their centroid within |ETA|<0.5 and the background fluctuations are characterized by DeltaPT which is the difference of the scalar sum of all track PT in the cone and the expected background. See the text of the paper for more details. Probability densities are presented for different random cone scenarios.

Table 24

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 21

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 20

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 17

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 15

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 12

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 11

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 1

CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB ... more CERN-LHC. Measurements of the inclusive PT distributions of primary charged particles from PB-PB collisions at a centre-of-mass energy per nucleon of 2.76 TeV. The data, based on 1.6*10**7 minimum-bias events recorded in 2010 covering the |eta| range < 0.8 and PT range 0.15-50 GeV/c, are presented as the charged particle distributions and nuclear modification factors RAA as a function of PT in 9 centrality intervals from 70-80% to 0-5%.

Table 5

CERN-LHC. Measurement of the pT-differential inclusive production cross section of the prompt cha... more CERN-LHC. Measurement of the pT-differential inclusive production cross section of the prompt charm-strange meson D_s^+ in the rapidity range |y| < 0.5. The analysis was performed on a data sample of 2.98*10^8 events collected in 2010 in proton-proton collisions at sqrt(s) = 7 TeV at the LHC using the ALICE detector with a minimum-bias trigger, with a corresponding integrated luminosity of 4.8 nb^-1. The ratios of the cross sections of four D meson species (namely D^0, D^+, D*^+ and D_s^+) are determined both as a function of pT and integrated over pT after extrapolating to the full pT range, together with the strangeness suppression factor in charm fragmentation.

Table 4

CERN-LHC. Measurement of the pT-differential inclusive production cross section of the prompt cha... more CERN-LHC. Measurement of the pT-differential inclusive production cross section of the prompt charm-strange meson D_s^+ in the rapidity range |y| < 0.5. The analysis was performed on a data sample of 2.98*10^8 events collected in 2010 in proton-proton collisions at sqrt(s) = 7 TeV at the LHC using the ALICE detector with a minimum-bias trigger, with a corresponding integrated luminosity of 4.8 nb^-1. The ratios of the cross sections of four D meson species (namely D^0, D^+, D*^+ and D_s^+) are determined both as a function of pT and integrated over pT after extrapolating to the full pT range, together with the strangeness suppression factor in charm fragmentation.

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