Summer Student Practice, Dubna, 2009 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 Joint Institute for Nuclear Research Supervised by: Dr. Armen Kechechyan, Valery Kizka Prof. Dr. Mikhail Tokarev UCT-CERN Research Centre, University of Cape Town

Summer Student Practice, Dubna, 2009 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

Summer Student Practice, Dubna, 2009 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

Summer Student Practice, Dubna, 2009 T c =170 MeV initial state pre-equilibrium QGP and Hydro. expansion Hadronization, mixed phase Hadronic interaction and chemical freeze-out Spatial & time evolution of heavy ion collisions high p T probes, anisotropy particle ratios To study the QCD under extreme conditions heavy ion collisions are investigated at relativistic energies. A new state of matter is expected to form, reflecting the early universe, few μs after the Big Bang. Elastic scattering and kinetic freeze-out Time (fm/c) ‏ kinetic freeze out temperature S.Bass. ε (GeV/fm 3 ) ‏

Summer Student Practice, Dubna, 2009 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 cm -2 s -1 p+p : 2 x cm -2 s -1 Beam polarizations P=70% Upton, Long Island, New York PP2PP RHIC

Summer Student Practice, Dubna, 2009 The STAR Detector

Summer Student Practice, Dubna, 2009 MRPC ToF barrel Ready for run 10 RPSD PMD FPD FMS EMC barrel EMC End Cap DAQ1000 Ready for run 9 FGT Complete Ongoing MTD R&D HFT TPC The STAR Detector

Summer Student Practice, Dubna, 2009 Main goal of investigations in relativistic AA collisions Search for and study new state of nuclear matter …, AGS, SPS, RHIC, LHC, … 200 GeV Au+Au 35-40% Cu+Cu 3-6% Central Au-Au s 1/2 =200 GeV RHIC & STAR  High energy-density and very strong interacting matter was created at RHIC.  RHIC data on dN /dη, v 2, R CP,… exhibit scaling laws.  Transition to the new state of matter does not manifest abrupt changes in observables. Central Pb-Pb s 1/2 =17 GeV SPS & NA49 LHC & ALICE Central Pb-Pb s 1/2 =5500 GeV  What kind of interacting matter is created ?  Thermodynamics, hydrodynamics, …  Phase transition, critical point, …  Self-similarity of created matter, … “White papers” STAR, PHENIX, PHOBOS & BRAHMS …, NICA, FAIR, …

Summer Student Practice, Dubna, 2009 AuAu Beam Energy Scan Program at RHIC 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 Search for Phase Transition and Critical Point  Elliptic and Directed Flow  Azimuthally Sensitive HBT  Fluctuations π/p, K/π, STAR Collaboration B.Abelev et al., Run 10 Beam Energy Scan at RHIC H.Crawford, AGS-RHIC Meeting, 2009 L.Kumar, SQM08 STAR Run 10 Plan for First Energy Scan Experimental Study of the QCD Phase Diagram and Search for the Critical Point

Summer Student Practice, Dubna, 2009 STAR AuAu & 9.2 GeV Central Au-Au s 1/2 =200 GeV RHIC & STAR Monte Carlo study of AuAu collisions ? 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,… )

Summer Student Practice, Dubna, 2009 Multiplicity distribution in Au-Au at s 1/2 = 17.3 GeV  events & 3 centrality classes: 0-10%, 10-30%, %.  Usage of UrQMD code to generate events and obtain data sample for analysis ( UrQMD simulation ‏ >800

Summer Student Practice, Dubna, 2009 p T spectra of charged particles in AuAu  exponential behavior pT< 2 GeV/c  a power behavior pT >2 GeV/c  the centrality dependence of spectra

Summer Student Practice, Dubna, 2009  Data sample were generated using MC UrQMD ‏ code.  events were generated.  Data were analyzed in ROOT framework (  p T spectra of hadron species produced in Au+Au collisions at different centralities were obtained.

Summer Student Practice, Dubna, 2009 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

Summer Student Practice, Dubna, 2009  Data sample were generated using MC UrQMD ‏ code.  events were generated.  Data were analyzed in ROOT framework (  Rapidity distribution of hadron species produced in Au+Au collisions at different centralities were obtained.

Summer Student Practice, Dubna, 2009 Energy density & Temperature System of charged hadrons produced in AuAu at 17.3 GeV Energy density p T distribution Centrality Energy density (GeV/fm 3 )‏ Temperature (MeV)‏ min.bias 6.0 ± ± % 12.8 ± ± % 7.4 ± ± % 3.1± ± 0.4 0

Summer Student Practice, Dubna, 2009 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.

Summer Student Practice, Dubna, 2009 National Research Foundation of South Africa Joint Institute for Nuclear Research, Russia Supervisors: Dr. Armen Kechechyan, Valery Kizka Prof. Dr. Mikhail Tokarev Acknowledgements

Summer Student Practice, Dubna, 2009 Thank You for Attention !

Summer Student Practice, Dubna, 2009 Thank You for Attention !

Summer Student Practice, Dubna, 2009 Back up slides

Summer Student Practice, Dubna, 2009 Statistical model Stable particle ratios are well described by statistical model. Statistical model assumes a system at thermal and chemical equilibrium described by grand canonical ensemble. Parameters: T chem : chemical freeze out temperature μ B and μ S : baryon and strangeness chemical potential γ S : strangeness supression factor 200GeV Au-Au

Summer Student Practice, Dubna, 2009 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)‏