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Frankfurt am Main, Germany

Baatar B.,Joint Institute for Nuclear Research | Barr G.,University of Oxford | Bartke J.,Polish Academy of Sciences | Betev L.,CERN | And 21 more authors.
European Physical Journal C | Year: 2013

The production of protons, anti-protons, neutrons, deuterons and tritons in minimum bias p+C interactions is studied using a sample of 385 734 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.9 GeV/c in transverse momentum and in Feynman x from -0.8 to 0.95 for protons, from -0.2 to 0.3 for anti-protons and from 0.1 to 0.95 for neutrons. Existing data in the far backward hemisphere are used to extend the coverage for protons and light nuclear fragments into the region of intra-nuclear cascading. The use of corresponding data sets obtained in hadron-proton collisions with the same detector allows for the detailed analysis and model-independent separation of the three principle components of hadronization in p+C interactions, namely projectile fragmentation, target fragmentation of participant nucleons and intra-nuclear cascading. © 2013 The Author(s). Source


Schuster T.,Fachbereich Physik der University
Journal of Physics G: Nuclear and Particle Physics | Year: 2011

Event-by-event fluctuations of produced particle multiplicities are believed to be sensitive to a deconfinement phase transition and the critical point of strongly interactingmatter. TheNA49 collaboration has conducted a systematic study of various fluctuation observables. In this contribution, recent results on hadron ratio fluctuations in central Pb+Pb collisions at √SNN= 6.3-17.3GeV are reported. These results are complemented by the centrality dependence of hadron ratio fluctuations at √SNN = 17.3GeV. A universal scaling was found, describing the energy and centrality dependence of the (K++ K? )/(π++ π - and (p +p̄)/(π+ + π -) ratio fluctuations purely by a change in the observed average hadron multiplicities. This scaling is broken for the fluctuations of the (K++ K? )/(p +p̄) and K +/p ratios, possibly hinting at a change in the baryon numberstrangeness correlation. © CERN 2011. Source


Anticic T.,Ruder Boskovic Institute | Baatar B.,Joint Institute for Nuclear Research | Barna D.,KFKI Research Institute | Bartke J.,Polish Academy of Sciences | And 73 more authors.
Physical Review C - Nuclear Physics | Year: 2010

Pion production in nuclear collisions at the Super Proton Synchrotron (SPS) is investigated with the aim to search, in a restricted domain of the phase diagram, for power laws in the behavior of correlations that are compatible with critical QCD. We analyzed interactions of nuclei of different sizes (p+p, C+C, Si+Si, Pb+Pb) at 158A GeV adopting, as appropriate observables, scaled factorial moments in a search for intermittent fluctuations in transverse dimensions. The analysis is performed for π+π- pairs with an invariant mass very close to the two-pion threshold. In this sector one may capture critical fluctuations of the sigma component in a hadronic medium, even if the σ meson has no well-defined vacuum state. It turns out that for the Pb+Pb system the proposed analysis technique cannot be applied without entering the invariant mass region with strong Coulomb correlations. As a result the treatment becomes inconclusive in this case. Our results for the other systems indicate the presence of power-law fluctuations in the freeze-out state of Si+Si approaching in size the prediction of critical QCD. © 2010 The American Physical Society. Source


Anticic T.,Ruder Boskovic Institute | Baatar B.,Joint Institute for Nuclear Research | Barna D.,Hungarian Academy of Sciences | Bartke J.,Polish Academy of Sciences | And 73 more authors.
Physical Review C - Nuclear Physics | Year: 2012

Measurements of charged pion and kaon production are presented in centrality selected Pb+Pb collisions at 40A GeV and 158A GeV beam energy as well as in semicentral C+C and Si+Si interactions at 40A GeV. Transverse mass spectra, rapidity spectra, and total yields are determined as a function of centrality. The system-size and centrality dependence of relative strangeness production in nucleus-nucleus collisions at 40A GeV and 158A GeV beam energy are derived from the data presented here and from published data for C+C and Si+Si collisions at 158A GeV beam energy. At both energies a steep increase with centrality is observed for small systems followed by a weak rise or even saturation for higher centralities. This behavior is compared to calculations using transport models (ultra-relativistic quantum molecular dynamics and hadron-string dynamics), a percolation model, and the core-corona approach. © 2012 American Physical Society. Source


Anticic T.,Ruder Boskovic Institute | Baatar B.,Joint Institute for Nuclear Research | Bartke J.,Polish Academy of Sciences | Beck H.,Fachbereich Physik der University | And 68 more authors.
European Physical Journal C | Year: 2015

We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5 % most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158A GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent is consistent with the value expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass collisions. © 2015, The Author(s). Source

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