Correspondence between HBT radii and the emission zone in non-central heavy ion collisions

In non-central collisions between ultra-relativistic heavy ions, the freeze-out distribution is anisotropic, and its major longitudinal axis may be tilted away from the beam direction. The shape and orientation of this distribution are particularly interesting, as they provide a snapshot of the evolving source and reflect the space-time aspect of anisotropic flow. Experimentally, this information is extracted by measuring pion HBT radii as a function of angle with respect to the reaction plane. Existing formulae relating the oscillations of the radii and the freezeout anisotropy are in principle only valid for Gaussian sources with no collective flow. With a realistic transport model of the collision, which generates flow and non-Gaussian sources, we find that these formulae approximately reflect the anisotropy of the freezeout distribution.Comment: 9 pages, 8 figure

Validity of the Hadronic Freeze-Out Curve

We analyze hadro-chemical freeze-out in central Pb+Pb collisions at CERN SPS energies, employing the hybrid version of UrQMD which models hadronization by the Cooper-Frye mechanism, and matches to a final hadron-resonance cascade. We fit the results both before and after the cascade stage using the Statistical Hadronization Model, to assess the effect of the cascade phase. We observe a strong effect on antibaryon yields except anti-{\Omega}, resulting in a shift in T and {\mu}_B. We discuss the implications for the freeze-out curve.Comment: 5 pages, 8 figures. To appear in the proceedings of Quark Matter 2011, the XXII International Conference on Ultrarelativistic Nucleus-Nucleus Collision

Characterization of the non-standard copper concentrates and potentials for their processing

Poznavanje sastava i karakteristika nestandardnih koncentrata bakra sulfidnog tipa, termodinamiĉkih i kinetiĉkih parametara, mehanizama procesa oksidacionog prţenja koncentrata, kao i tehnoloških mogućnosti za odvajanje štetnih primesa i ukljuĉivanje u konvencionalnu pirometaluršku proizvodnju bakra, neki su od vaţnih aspekata obuhvaćenih istraţivanjem u okviru ove doktorske disertacije. Za eksperimentalna istraţivanja bila su odabrana tri polimetaliĉna koncentrata bakra sulfidnog tipa, jedna rudna sirovina enargitskog tipa i tri sintetisane mešavine polaznih koncentrata sa dodatkom odreĊene koliĉine Pb, Zn, Ni i Cd u obliku sulfida u cilju dobijanja nestandardnih koncentrata. Karakterizacija je obuhvatala: 1) odreĊivanje hemijskog sastava polaznih uzoraka putem ICP-AES, AAS, elektrogravimetrije i EDXRF; 2) odreĊivanje mineraloškog sastava polaznih uzoraka i produkata oksidacionog prţenja putem XRD analize; i 3) mikrostrukturne analize polaznih uzoraka i produkata oksidacionog prţenja putem SEM-EDS metode i optiĉke mikroskopije. U cilju boljeg poznavanja termodinamiĉkih karakteristika nestandardnih koncentrata bakra, izvršena je termodinamiĉka analiza procesa oksidacije u sistemu Cu−Me−S−O (Me = Fe, Pb, Zn, As, Ni, Cd, Hg i Sb) i konstruisani su dijagrami stabilnosti faza (Phase Stability Diagrams) kao zavisnosti log pSO2 = f ( log pO2) na temperaturama od 25 °C do 1000 °C. OdreĊene su vrednosti ΔG0T na 450, 650 i 900 °C za moguće reakcije u ispitivanim Me-S-O sistemima. Konstruisani su dijagrami ravnoteţnog sastava i odreĊeni odnosi gasa i koncentrata (šarţe) za optimalne uslove procesa oksidacionog prţenja koncentrata. Analizirano je ponašanje svake od prisutnih komponenti šarţe tokom zagrevanja do 1000 °C. Termijska analiza vršena je putem DTA-TG analize u neizotermskim uslovima na osnovu koje su definisani mehanizmi procesa oksidacije ispitivanih koncentrata i sintetisanih mešavina. Za definisanje kinetiĉkih parametara procesa oksidacionog prţenja koncentrata bakra, izvršena je kinetiĉka obrada eksperimentalnih rezultata polaznih koncentrata i sintetisanih mešavina, primenom metoda izotermske (metoda Sharpa) i neizotermske kinetike (metode Kissingera i Ozawe) i odreĊene energije aktivacije procesa oksidacionog prţenja koncentrata. Analiziran je uticaj koliĉine prisutnih štetnih primesa u koncentratima bakra, temperature i vremena na kinetiĉke pokazatelje procesa oksidacionog prţenja...Knowledge of the composition and characteristics of the non-standard sulphide type copper concentrates, thermodynamic and kinetic parameters, mechanisms of oxidative roasting process, as well as the technological possibilities for the separation of impurities and the implementation in the conventional pyrometallurgical copper production, represent some of the important aspects that were surveyed in the frame of this doctoral dissertation. For the experimental investigations three sulphide polymetallic copper concentrates, one enargite-type raw ore material and three synthesized mixtures, made from the initial concentrates with the addition of certain amounts of Pb, Zn, Ni and Cd in the form of sulfides in order to obtain non-standard concentrates, were selected. Characterization included: 1) determination the chemical composition of the initial samples by ICP-AES, AAS, electrogravimetry and EDXRF; 2) determination the mineralogical composition of the initial samples and products of oxidative roasting by XRD analysis; and 3) the microstructural analysis of the initial samples and products of oxidative roasting by SEM-EDS methods and optical microscopy. Due to better understanding of the thermodynamic properties of non-standard copper concentrates, thermodynamic analysis of oxidation process in the system Cu-S-Me-O (Me = Fe, Pb, Zn, As, Ni, Cd, Hg and Sb) was done. Phase Stability Diagrams as a functions log pSO2 = f (log pO2) were constructed at temperatures from 25 °C to 1000 °C. The values of ΔG0T at 450, 650 and 900 °C for the possible reactions in the investigated Me-S-O systems were calculated. Equilibrium composition diagrams were constructed and mole fractions of gas and concentrate (batch) for the optimal oxidation process were determined. The behaviour of the each batch component during heating up to 1000 ° C was analysed. Thermal analysis in isothermal and non-isothermal conditions was performed by DTA-TG- analysis under which the oxidation mechanisms of investigated concentrates and mixtures were defined. For defining the kinetic parameters of oxidative roasting process, the kinetic analysis of the experimental results for the initial concentrates and synthesized mixtures was done, using the methods of isothermal (Sharp’s method) and non-isothermal kinetics (methods of Kissinger and Ozawa) and activation energies of the oxidation were determined. The impacts of harmful impurities in copper concentrates and influence of temperature and time on kinetic parameters of the process were analysed..

Usage of Biologics on Tomatoes and Peppers

In fruit growing, nowadays a lot of chemical products are used (insecticide, fungicide etc.) in order to protect the plants. However, lately the markets are in need of gardening products which are not treated with pesticide but protected with biologics. In gardening, biological fight against the insects and the diseases is not much maintained because the shares are lower and the gardening products are on a great demand and are very profitable. Due to the great profit of the gardening products, less attention is paid to the biological fight for protection. However, the great environmental pollution evokes great interest in consuming healthy gardening products. Due to the mentioned reasons, lately, fruit producers show interest for usage of biologics to protect the gardening products from some insects and diseases. There appear to be many biologics but the producers of gardening products are not well informed because the interest of usage of biologics is not high. By all means, the market provides verified biologics which show good production results. The great interest in usage of biologics to protect the gardening products from diseases and insects increases, whereas the interest of research institutions to discover better biologics is getting bigger

Recent Results on Strangeness Production at RHIC

Due to its large acceptance, the STAR experiment has acquired a wealth of data on strangeness production for a variety of collisions systems and energies, from p+p to Au+Au. By using the yields and spectra, we address the evolution of the bulk system, including strangeness enhancement and the flavour dependence of radial and elliptic flow. Utilising the fact that we can identify strange baryons and mesons, we investigate different hadronization mechanisms in the intermediate and high p$_{T}$ regions. The ratios of the particle yields, measured to high p$_{T}$, are used to further investigate the range and applicability of the previously reported anomalous baryon production. We also study two-particle azimuthal correlations of identified particles in order to investigate any flavour dependence of jet fragmentation in the available p$_{T}$ range. Data was presented for a number of different collision systems and energies.Comment: Proceedings of SQM'06 Conference, LA, 2006 (submitted to J. Phys. G

Xi and AntiXi production in Pb+Pb collisions at 40 AGeV at CERN SPS

First results on the production of Xi and AntiXi hyperons in Pb+Pb interactions at 40 AGeV are presented. The AntiXi/Xi ratio at midrapidity is studied as a function of collision centrality. The ratio shows no significant centrality dependence within statistical errors; it ranges from 0.07 to 0.15. The AntiXi/Xi ratio for central Pb+Pb collisions increases strongly with the collision energy.Comment: 6 pages, 6 figures, proceedings of SQM03, to be published in Journal of Physics G; V2: changes in table 1 and figure

Recent results on strangeness production from NA49

We present a summary of measurements of strange particles performed by the experiment NA49 in inelastic p+p interactions, as well as semi-central C+C and Si+Si, central Pb+Pb, and minimum bias Pb+Pb collisions in the energy range $\sqrt{s_{NN}}$ = 6.3 - 17.3 GeV. New results on $\pi^{-}$, $K^{+}$ and $K^{-}$ production in minimum bias Pb+Pb collisions at $\sqrt{s_{NN}}$ = 8.7 and 17.3 are shown. Furthermore the strangeness enhancement factor at $\sqrt{s_{NN}}$ = 17.3 GeV is presented and compared to the results from NA57 and STAR. Energy dependence of strange particle yields normalized to pion yields is presented. New data on $$ production are shown at $\sqrt{s_{NN}}$ = 17.3 GeV. Furthermore we present the energy dependence of $K/\pi$ and $K/p$ fluctuations. The data are compared with model predictions.Comment: 9 pages, 7 figures, Submitted to J. Phys. G (Proceedings of the International Conference on Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, September 27 - October 2, 2009

Interferometry signatures for QCD first-order phase transition in heavy ion collisions at GSI-FAIR energies

Using the technique of quantum transport of the interfering pair we examine the Hanbury-Brown-Twiss (HBT) interferometry signatures for the particle-emitting sources of pions and kaons produced in the heavy ion collisions at GSI-FAIR energies. The evolution of the sources is described by relativistic hydrodynamics with the system equation of state of the first-order phase transition from quark-gluon plasma (QGP) to hadronic matter. We use quantum probability amplitudes in a path-integral formalism to calculate the two-particle correlation functions, where the effects of particle decay and multiple scattering are taken into consideration. We find that the HBT radii of kaons are smaller than those of pions for the same initial conditions. Both the HBT radii of pions and kaons increase with the system initial energy density. The HBT lifetimes of the pion and kaon sources are sensitive to the initial energy density. They are significantly prolonged when the initial energy density is tuned to the phase boundary between the QGP and mixed phase. This prolongations of the HBT lifetimes of pions and kaons may likely be observed in the heavy ion collisions with an incident energy in the GSI-FAIR energy range.Comment: 16 pages, 4 figure

Omega and AntiOmega production in Pb+Pb and p+p collisions at 30, 40 and 158 AGeV

We report preliminary results on Omega and AntiOmega production in central Pb+Pb collisions at 30, 40 and 158 AGeV and p + p interactions at 158 GeV. The midrapidity AntiOmega/Omega ratio is estimated to be 0.45 +- 0.05 and 0.41 +- 0.18 for central Pb+Pb collisions at 158 and 40 AGeV, respectively. The corresponding value for 158 GeV p+p interactions is 0.67 +- 0.62. For central Pb+Pb collisions at 158 AGeV fully corrected distributions are obtained. The inverse slope parameters of the transverse mass spectrum and total yields are T(Omega) = 276 +- 23 MeV, = 0.47 +- 0.07 and T(AntiOmega) = 285 +- 39 MeV, = 0.15 +- 0.02.Comment: Contribution to the proceedings of "Strangeness in Quark Matter 2003" (March 2003, Atlantic Beach NC, USA), to be published in Journal of Physics G., 6 pages, 6 figure

Estimations of Ωˉ+/Ω−\bar{\Omega}^+/\Omega^- at RHIC from a QGP Model with Diquarks

Assuming that axial-vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature $T_c$, baryons can be produced from quark-diquark interactions. In RHIC conditions ($\sqrt{s_{NN}} = 130GeV$ and $200GeV$), the ratio $\bar{\Omega}^+/\Omega^-$ may be larger than 1, based on the concept that QGP with diquarks would exist. This unusual result might be a helpful evidence for QGP existing in RHIC.Comment: 6 pages, 1 figure. accepted by J.Phys.