7,551 research outputs found

    Overview and Recent Results from BRAHMS

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    The BRAHMS experiment was designed to measure and characterize in particular the properties of rapidity dependence of particle production in heavy ion collisions. The data-taking is now over, results of several years of analysis have been published and demonstrates several important features of the rapidity dependence, not envisioned from the start of the RHIC program. The bulk properties of the system formed at high rapidity resemble that of systems at lower energies at mid-rapidity when referenced via the baryo-chemical potential. New physics in AA are essentially observed at mid-rapidity including the demonstration that high-\pT suppression is a final state effect. Another key result is that in d+A collisions at forward rapidities where the very low-x region of the nucleus was probed, a strong suppression of pion production was observed consistent with the picture of gluon saturation. The latest results examines the centrality and rapidity dependence of nuclear stopping, the particle production of pions, collective expansion vs. rapidity, and the baryon enhancement at intermediate values of \pT .Comment: 8 pages, 6 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee Fixed typos and minor text issues as per organizers review reques

    Charmonium production in pp collisions with ALICE

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    The ALICE Collaboration studies the production of J/psi meson in pp collisions at the center-of-mass energies of 2.76 and 7 TeV at mid- and forward-rapidity. Inclusive production cross-sections are presented as a function of the collision energy, rapidity and transverse-momentum. The J/psi polarization measurements in the helicity and Collins-Soper frames are discussed. A novel result on the correlation between the collision charged particle multiplicity and J/psi yield is also shown.Comment: Talk given at the XX International Workshop on Deep-Inelastic Scattering (DIS2012), 26-30 March 2012, Bonn, Germany; 4 pages, 5 figure

    The management of cultural adjustment: Central-South-East European ethnic minorities in the USA

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    The paper focuses on one particular instance in the management of change as accomplished/implemented in the USA by the ethnic minorities originally from Italy, Greece and Romania. The author presents a diachronic survey of the literature against the author’s own findings. The paper identifies common patterns in the cultural adjustment of all three ethnic groups surveyed and analyses them against the specific developmental pressures in each group. Historic, economic and sociological data contribute to outlining the distinct profile of each ethnic groups under investigation, as well as the assimilation patterns at work throughout its evolution in the new US cultural environment.ethnicity affirmed, ethnicity under attack, peripheral ethnicity

    XmaxμX_{max}^{\mu} vs. NμN^{\mu} from Extensive Air Showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory

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    We study the possibility of primary mass estimation for Ultra High Energy Cosmic Rays (UHECR's) using the XmaxμX_{max}^{\mu} (the height where the number of muons produced on the core of Extensive Air Showers (EAS) is maximum) and the number NμN^{\mu} of muons detected on ground. We use the 2D distribution - XmaxμX_{max}^{\mu} against NμN^{\mu} in order to find its sensitivity to the mass of the primary particle. For that, we construct a 2D Probability Function Prob(p,Fe  Xmaxμ,Nμ)Prob(p,Fe \ | \ X_{max}^{\mu},N^{\mu}) which estimates the probability that a certain point from the plane (Xmaxμ(X_{max}^{\mu}, Nμ)N^{\mu}) corresponds to a shower induced by a proton, respectively an iron nucleus. To test the procedure, we analyze a set of simulated EAS induced by protons and iron nuclei at energies of 1019eV10^{19} eV and 2020^{\circ} zenith angle with CORSIKA. Using the Bayesian approach and taking into account the geometry of the infill detectors from the Pierre Auger Observatory, we observe an improvement in the accuracy of the primary mass reconstruction in comparison with the results obtained using only the XmaxμX_{max}^{\mu} distributions

    Restoration of azimuthal symmetry of muon densities in extended air showers

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    At ground level, the azimuthal distribution of muons in inclined Extensive Air Showers (EAS) is asymmetric, mainly due to geometric effects. Several EAS observables sensitive to the primary particle mass, are constructed after mapping the density of secondary particles from the ground plane to the shower plane (perpendicular to the shower axis). A simple orthogonal projection of the muon coordinates onto this plane distorts the azimuthal symmetry in the shower plane. Using CORSIKA simulations, we correct for this distortion by projecting each muon onto the normal plane following its incoming direction, taking also into account the attenuation probability. We show that besides restoring the azimuthal symmetry of muons density around the shower axis, the application of this procedure has a significant impact on the reconstruction of the distribution of the muon production depth and of its maximum, XmaxμX_{\rm max}^{\mu}, which is an EAS observable sensitive to the primary particle mass. Our results qualitatively suggest that not including it in the reconstruction process of XmaxμX_{\rm max}^{\mu} may introduce a bias in the results obtained by analyzing the actual data on the basis of Monte Carlo simulations.Comment: Accepted for publication in Astroparticle Physic

    J/ψJ/\psi Production in Pb-Pb collisions at sNN=\sqrt{s_{NN}}=2.76 TeV

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    We report on the J/ψJ/\psi production in Pb-Pb collisions at sNN=\sqrt{s_{NN}}=2.76 TeV recorded with ALICE during the 2010 and 2011 LHC runs. The J/ψJ/\psi candidates are reconstructed using the e+ee^{+}e^{-} and μ+μ\mu^{+}\mu^{-} decay channels at mid- and forward rapidity, respectively. We show the J/ψJ/\psi nuclear modification factor RAAR_{AA} as a function of centrality, transverse momentum and rapidity. Our results are compared to the lower energy measurements from PHENIX and to model calculations.Comment: Proceedings to the FAIRNESS workshop for young scientists with research interests focused on physics at FAIR, Hersonissos, Greece, Sept. 3-8, 2012. 5 pages, 4 figures; Submitted to Journal of Physics Conference Serie

    Small-x Physics with the ALICE experiment at the CERN-LHC

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    High energy p-p, p-Pb and Pb-Pb collisions at the CERN-LHC offer unprecedented opportunities for studying wide variety of physics at small Bjorken-x. Here we discuss capabilities of the ALICE experiment at the CERN-LHC for probing small-x QCD physics. A new forward electromagnetic calorimeter is being proposed as an ALICE upgrade to explore the small-x region in more detail.Comment: Prepared for the Workshop on "Saturation, the Color Glass Condensate and Glasma: What Have we Learned from RHIC?" - to be published in Nucl. Phys.

    QCD Saturation and Deuteron-Nucleus Collisions

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    We make quantitative predictions for the rapidity and centrality dependencies of hadron multiplicities in dA collisions at RHIC basing on the ideas of parton saturation in the Color Glass Condensate.Comment: 16 pages, 5 figures; added Erratum with a discussion of centrality selection procedure and comparison to the published experimental result

    Quantification of growth hormone in serum by isotope dilution mass spectrometry

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    Inter-assay variation of antibody based routine tests is hampering comparability of measurement results for growth hormone (GH) between different laboratories and decision making in clinical practice. Here it is demonstrated, that quantification of GH by isotope dilution mass spectrometry (IDMS) constitutes a way to precise and reliable results which can be referred to in evaluation of performance of commercial test kits. With the IDMS method developed, tryptic cleavage products YSFLQNPQTSLCFSESIPTPSNR (T6) and LEDGSPR (T12) of GH are quantified by LC/MS-MS using the isotopically labeled forms of the peptides as internal standards. The GH cleavage fragments are obtained by whole-serum tryptic proteolysis and then extracted from the resulting mixture by semi-preparative reversed phase liquid chromatography followed by strong cation-exchange chromatography. Method validation basing on recovery of recombinant 22 kDa GH spiked to blank serum in defined amounts covering the intended concentration range (3-30 µg/L) would yield mean recoveries of 101.6% (100.7%), standard deviations of 2.5% (2.4%) and combined uncertainties (_u~c~_) of 3.0% (2.5%) if quantifying T6 (T12) as GH derived fragments, while the LOQ were 1.7 µg/L (2.7 µg/L). Potential to acquisition of reference values is exemplified by application to serum materials used in a recent quality assessment exercise for routine laboratories
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