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Analysis of UrQMD Data Obtained for Relativistic Au+Au Collisions at 17.3 GeV

Joint Institute for Nuclear Research. Analysis of UrQMD Data Obtained for Relativistic Au+Au Collisions at 17.3 GeV for STAR detector. F. Nemulodi, M.W. Paradza & D. S. Worku. UCT-CERN Research Centre, University of Cape Town. Supervised by: Dr. Armen Kechechyan, Valery Kizka

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Analysis of UrQMD Data Obtained for Relativistic Au+Au Collisions at 17.3 GeV

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  1. Joint Institute for Nuclear Research Analysis of UrQMD Data Obtained for Relativistic Au+Au Collisions at 17.3 GeV for STAR detector F. Nemulodi, M.W. Paradza & D. S. Worku UCT-CERN Research Centre, University of Cape Town Supervised by: Dr. Armen Kechechyan, Valery Kizka Prof. Dr. Mikhail Tokarev

  2. Outline • Introduction (motivation & goals)‏ • Relativistic Heavy Ion Collider (RHIC)‏ • Solenoidal Tracker At RHIC (STAR) Detector • Spatial and time evolution of a nuclear collision • Results of Monte Carlo Simulation for Au+Au collisions • Summary

  3. Motivation & Goals • Study of the deconfined • system of strongly interacting quarks and gluons produced in relativistic heavy ion collisions with characterised size more than 1 fm. • Understanding the methods of data analysis in high energy heavy ion physics. RHIC beam energy scan - Search for critical point - Chiral symmetry restoration

  4. Spatial & time evolution of heavy ion collisions • To study the QCD underextreme conditionsheavy ion collisions areinvestigated at relativisticenergies. • A new state of matter is expected to form, reflecting the early universe,few μs afterthe Big Bang. ε (GeV/fm3)‏ Tc=170 MeV Time (fm/c)‏ pre-equilibrium Hadronization, mixed phase Hadronic interactionand chemical freeze-out Elastic scattering and kinetic freeze-out QGP and Hydro. expansion initial state kinetic freeze out temperature high pT probes, anisotropy particle ratios S.Bass.

  5. Relativistic Heavy Ion Collider, RHIC • 3.83 km circumference • Two separated rings • 120 bunches/ring • 106 ns bunch crossing time • A+A, p+A, p+p • Maximum Beam Energy : • 500 GeV for p+p • 200A GeV for Au+Au • Luminosity • Au+Au: 2 x 1026 cm-2 s-1 • p+p : 2 x 1032 cm-2 s-1 • Beam polarizations • P=70% PP2PP RHIC Upton, Long Island, New York

  6. The STAR Detector

  7. MTD EMC barrel MRPC ToF barrel Ready for run 10 EMC End Cap RPSD FMS FPD TPC PMD Complete Ongoing DAQ1000 Ready for run 9 R&D HFT FGT The STAR Detector

  8. Central Au-Au s1/2=200 GeV RHIC & STAR Main goal of investigations in relativisticAAcollisions Search for and study new state of nuclear matter …, AGS, SPS, RHIC, LHC, … SPS & NA49 Central Pb-Pb s1/2=17 GeV LHC & ALICE 200 GeV Cu+Cu 3-6% Au+Au 35-40% Central Pb-Pb s1/2=5500 GeV …, NICA, FAIR, … • High energy-density and very strong • interacting matter was created at RHIC. • RHIC data on dN /dη , v2 , RCP ,… • exhibit scaling laws. • Transition to the new state of matter does not • manifest abrupt changes in observables. • What kind of interacting matter is created ? • Thermodynamics, hydrodynamics, … • Phase transition, critical point, … • Self-similarity of created matter, … “White papers” STAR, PHENIX, PHOBOS & BRAHMS

  9. STAR Run 10 Plan for First Energy Scan  AuAuBeam Energy Scan Program atRHIC Experimental Study of the QCD Phase Diagram and Search for the Critical Point Search for Phase Transition and Critical Point • Elliptic and Directed Flow  • Azimuthally Sensitive HBT • Fluctuationsπ/p, K/π, <pT> Turn off of QGP Signatures  and Other New Phenomena • Constituent Quark Number Scaling • High & Intermediate pT Spectra:  • QGP Opacity and the Baryon Anomaly • Pair Correlations in ∆φ&∆η • Local P violation in Strong Interactions STAR Collaboration B.Abelev et al., Run10 Beam Energy Scan at RHIC H.Crawford, AGS-RHIC Meeting, 2009 L.Kumar, SQM08

  10. Monte Carlo study of AuAucollisions AuAu & 9.2 GeV Central Au-Au s1/2=200 GeV STAR RHIC & STAR 9.2 GeV 17.3 GeV 200 GeV ? Search for location of critical point and clear signatures of phase transition over a wide kinematical range (collision energy, size of nucleus, centrality,… )

  11. Multiplicity distribution in Au-Au at s1/2= 17.3 GeV UrQMD simulation‏ >800 • 11000 events&3 centrality classes: 0-10%, 10-30%, 30-60 %. • Usage of UrQMD code to generate events and obtain data • sample for analysis (http://th.physik.uni-frankfurt.de/~urqmd/)‏

  12. pT spectra of charged particles in AuAu • exponential behavior • pT< 2 GeV/c • a power behavior • pT >2 GeV/c • the centrality dependence of spectra

  13. Data sample were • generated using MC • UrQMD ‏ code. • 11000 events were • generated. • Data were analyzed • in ROOT framework • (http://root.cern.ch/)‏ • pT spectra of hadron • species produced in • Au+Au collisions at • different centralities • were obtained.

  14. Rapidity distributions of charged hadrons • Smooth behavior of a multiplicity density vs. rapidity y. • Width of the dN/dy decreases as centrality increases. *) arbitrary scaling factor

  15. Data sample were • generated using MC • UrQMD ‏ code. • 11000 events were • generated. • Data were analyzed • in ROOT framework • (http://root.cern.ch/)‏ • Rapidity distribution • of hadron species • produced in Au+Au • collisions at different • centralities were • obtained.

  16. Energy density & Temperature Centrality Energy density (GeV/fm3)‏ Temperature (MeV)‏ min.bias 6.0 ± 0.1 198.8 ± 0.2 0-10% 12.8 ± 0.6 203.1 ± 0.2 10-30% 7.4 ± 0.3 200.9 ± 0.3 30-60% 3.1± 0.5 194.5 ± 0.4 System of charged hadrons produced in AuAu at 17.3 GeV Energy density pT distribution 0

  17. Summary • Monte Carlo study of Au-Au collisions at the energy 17.3 GeV using UrQMD generator in the ROOT framework was performed. • Monte Carlo data sample for Au-Au collisions was analyzed. Rapidity distribution of produced pions, kaons, protons and antiprotons at different centralities were obtained. • Transverse momentum spectra of pions, kaons, proton and antiprotons at different centralities were obtained. • Temperature and energy density values for system consisted of charged hadrons with respect to each centrality classes were estimated. Higher statistics of generated MC events is necessary for comparison with future STAR data.

  18. Acknowledgements National Research Foundation of South Africa Joint Institute for Nuclear Research, Russia Supervisors: Dr. Armen Kechechyan, Valery Kizka Prof. Dr. Mikhail Tokarev

  19. Thank You for Attention !

  20. Thank You for Attention !

  21. Back up slides

  22. Statistical model • Statistical model assumes a system at thermal and chemical equilibrium described by grand canonical ensemble. • Parameters: • Tchem: chemical freeze out temperature • μB and μS: baryon and strangeness chemical potential • γS: strangeness supression factor 200GeV Au-Au • Stable particle ratios are well describedby statistical model. http://hep.phy.uct.ac.za/~wheaton/

  23. Spatial evolution of a heavy ion collision • Lorenz contracted heavy ions approaching.. relativistic speeds cause the ions to appear disk –like • Ions interpenetrates, individual particles scatter • Deconfined quarks and gluons, plasma forms:- very short –lived, not observable • Formation of hadrons observable particles, analysis of this reveals information about QGP (quark gluon plasma)‏

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