Summer Student Practice, Dubna, 2009
Analysis of UrQMD Data Obtained forRelativistic 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
Tc=170 MeV
initial state
pre-equilibriumQGP and
Hydro. expansion
Hadronization,mixed phase
Hadronic interactionand chemical freeze-out
Spatial & time evolution of heavy ion collisions
high pT 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 scatteringand kinetic freeze-out
Time (fm/c)
kinetic freeze out
temperature
S.Bass.
ε (G
eV
/fm
3)
Summer Student Practice, Dubna, 2009
Relativistic Heavy Ion Collider, RHIC
3.83 km circumferenceTwo separated rings• 120 bunches/ring• 106 ns bunch crossing timeA+A, p+A, p+pMaximum 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%
Upton, Long Island, New York
PP2PPRHIC
Summer Student Practice, Dubna, 2009
The STAR Detector
Summer Student Practice, Dubna, 2009
MRPC ToF barrelMRPC ToF barrel
Ready for run 10Ready for run 10
RPSD
PMD
FPD
FMS
EMC barrel
EMC End Cap
DAQ1000DAQ1000
Ready for run 9 FGT
Complete
Ongoing
MTD
R&DHFT
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 s1/2=200 GeV
RHIC & STAR
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.
Central Pb-Pb s1/2=17 GeV
SPS & NA49
LHC & ALICE
Central Pb-Pb s1/2=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, <pT>
STAR CollaborationB.Abelev et al., Run 10 Beam Energy Scan at RHICH.Crawford, AGS-RHIC Meeting, 2009L.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 GeVCentral Au-Au s1/2=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 s1/2= 17.3 GeV
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/)
UrQMD simulation
>800
Summer Student Practice, Dubna, 2009
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
Summer Student Practice, Dubna, 2009
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.
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.
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.
Summer Student Practice, Dubna, 2009
Energy density & Temperature
12π pT
d 2NdpT dy
= A exp {−mTT
}
System of charged hadrons produced in AuAu at 17.3 GeV
Energy density pT distribution
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
0
Bj
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.
http://hep.phy.uct.ac.za/~wheaton/
• Statistical model assumes a systemat thermal and chemical equilibrium described by grand canonical ensemble.
• Parameters:
• Tchem: chemical freeze outtemperature• μB and μS: baryon and strangeness chemical potential• γS: 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)