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Henrik Tydesjö March 17 2003
OUTLINEOUTLINE
- The Quark Gluon Plasma
- The Relativistic Heavy Ion Collider (RHIC)
- The PHENIX Experiment
- Event-by-Event Net-Charge Fluctuations Simulations PHENIX Analysis
Henrik Tydesjö March 17 2003
QUARK GLUON PLASMAQUARK GLUON PLASMA
At extremely High Densities & TemperaturesNuclear Matter may undergo a Phase Transitionto a state called the Quark Gluon Plasma (QGP)
Henrik Tydesjö March 17 2003
QUARK GLUON PLASMAQUARK GLUON PLASMA
DECONFINEMENTDECONFINEMENT
PHASETRANSITION
Henrik Tydesjö March 17 2003
QUARK GLUON PLASMAQUARK GLUON PLASMA
CHIRAL SYMMETRY
RESTORATION
CHIRAL SYMMETRY
RESTORATION
Quark Masses 0
Henrik Tydesjö March 17 2003
Phase Diagram of Nuclear MatterPhase Diagram of Nuclear Matter
Early Universe
HadronGas
QGP
Neutron StarsNeutron Stars??????
Ultra-RelativisticHeavy-Ion Collisions
???
Henrik Tydesjö March 17 2003
Relativistic Heavy Ion Collider (RHIC)Relativistic Heavy Ion Collider (RHIC)
Brookhaven, Long Island, New York
Henrik Tydesjö March 17 2003
Relativistic Heavy Ion Collider (RHIC)Relativistic Heavy Ion Collider (RHIC)Au+Au Collisions 100 AGeV per
beam
Henrik Tydesjö March 17 2003
~ 460 Members
57 Institutions
12 Countries
~ 460 Members
57 Institutions
12 Countries
Collaboration
Henrik Tydesjö March 17 2003
Central Magnet
Beam-BeamCounters
Muon ArmSpectrometers Central Arm
Spectrometers
Henrik Tydesjö March 17 2003
Central Arms
Pad Chambers
Charged ParticleTracking
Electron, Photon Detection
Hadron Identification
Henrik Tydesjö March 17 2003
Pad Chambers- Multi-Wire Proportional Chambers
- Fine Granularity Pixel Pad Readout
- Provide Space Points for Track Recognition
Henrik Tydesjö March 17 2003
Pad Chambers- Multi-Wire Proportional Chambers
- Fine Granularity Pixel Pad Readout
- Provide Space Points for Track Recognition
- 172,800 Readout Channels
- Chip-On-Board Technique
Readout Cards (ROCS) Placed on the Chambers
- Data Transfer via Fiber Optic Links
Readout Card (ROC)
Henrik Tydesjö March 17 2003
Event Display
CentralAu+Au
Collision
370globaltracks
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
Event-by-EventNet Charge Fluctuations
in Local Regions of Phase Space
Decrease of Fluctuationsproposed as a signal for the QGP
Predictions range up to an 80% reduction
Henrik Tydesjö March 17 2003
Hadronization
???
Pion GasPion Gas
QGPQGP
NET CHARGE FLUCTUATIONS
+ 1/3
+ 2/3+ 1
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
Charge Q in each event:
nnQ
Variance of Q:
22)( QQQV
Random Particle Emission:
chnnnQV )(
chn
QVQv
)()(
Normalized Variance:
Henrik Tydesjö March 17 2003
1000 particles per event
assigned: charge +1 or –1 ,
azimuthal angle
NET CHARGE FLUCTUATIONS
SIMULATION
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
SIMULATION
Charge is globally conservedapQv 1)(
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
SIMULATION
Efficiency Dependenceea ppQv 1)(
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
SIMULATION
Uncorrelated Background Contribution)1(1)( bkga fpQv
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
SIMULATION
Decays of Neutral Resonances (e.g. , )introduce positive correlations between n+ and n–
width = 30º
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
SIMULATION
Decays of Neutral Resonances
fres = 0.3
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
SIMULATION
Simple QGP model:yprobabilit equal with hadronize ,,, nscombinatioquark ddudduuu
producing 2 or 3 pions, separated in azimuth (Gaussian width=10º)
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
RHIC 1st run period
GeVsNN 130
~ 500 000 events
|zvertex| < 17 cm
pT > 200 MeV/c
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
BBCs used for triggering
corresponding to 92% of inelastic cross-section
Centrality classes
determined from BBC+ZDC information
0-5%5-10%
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
pT , of positive and negative particles
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
Reduction not as large as predicted for QGPConsistent with resonance gas
Global ChargeConservation
10% most central events
Henrik Tydesjö March 17 2003
NET CHARGE FLUCTUATIONS
Fluctuations independent of centrality
)(019.0)(007.0965.0)( syststatQv 10% most central events:
Henrik Tydesjö March 17 2003Henrik Tydesjö March 17 2003
SUMMARYSUMMARY- An introduction was given to: Quark Gluon Plasma Relativistic Heavy-Ion Collider (RHIC) PHENIX Experiment
- The behavior of Net-Charge Fluctuations in different scenarios was described in simulations
- Results on Net-Charge Fluctuations in PHENIX was presented: Fluctuation result below pure global charge conservation Reduction not as drastic as predicted for a QGP Consistent with resonance gas prediction
Henrik Tydesjö March 17 2003