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OUTLINE - 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 PLASMA At extremely High Densities & Temperatures Nuclear Matter may undergo a Phase Transition to a state called the Quark Gluon Plasma (QGP) Henrik Tydesjö March 17 2003 QUARK GLUON PLASMA DECONFINEMENT PHASE TRANSITION Henrik Tydesjö March 17 2003 QUARK GLUON PLASMA CHIRAL SYMMETRY RESTORATION Quark Masses Henrik Tydesjö March 17 2003 0 Phase Diagram of Nuclear Matter Early Universe Ultra-Relativistic Heavy-Ion Collisions ??? QGP Hadron Gas Henrik Tydesjö March 17 2003 Neutron Stars ??? Relativistic Heavy Ion Collider (RHIC) Brookhaven, Long Island, New York Henrik Tydesjö March 17 2003 Relativistic Heavy Ion Collider (RHIC) Au+Au Collisions Henrik Tydesjö March 17 2003 100 AGeV per beam Collaboration ~ 460 Members 57 Institutions 12 Countries Henrik Tydesjö March 17 2003 Central Magnet Beam-Beam Counters Muon Arm Spectrometers Central Arm Spectrometers Henrik Tydesjö March 17 2003 Central Arms Charged Particle Tracking Electron, Photon Detection Hadron Identification Pad Chambers 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 Readout Card (ROC) - 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 Henrik Tydesjö March 17 2003 Event Display Central Au+Au Collision 370 global tracks Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS Event-by-Event Net Charge Fluctuations in Local Regions of Phase Space Decrease of Fluctuations proposed as a signal for the QGP Predictions range up to an 80% reduction Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS QGP Pion Gas +1 Henrik Tydesjö March 17 2003 + 1/3 + 2/3 NET CHARGE FLUCTUATIONS Charge Q in each event: Random Particle Emission: Q n n V (Q) n n nch Variance of Q: Normalized Variance: V (Q) Q Q 2 Henrik Tydesjö March 17 2003 2 V (Q) v(Q) nch NET CHARGE FLUCTUATIONS SIMULATION 1000 particles per event assigned: charge +1 or –1 , azimuthal angle Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS SIMULATION Charge is globally conserved v(Q) 1 pa Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS SIMULATION Efficiency Dependence v(Q) 1 pa pe Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS SIMULATION Uncorrelated Background Contribution v(Q) 1 pa (1 fbkg ) 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: quark combinatio ns uu , ud , du , dd hadronize with equal probabilit y producing 2 or 3 pions, separated in azimuth (Gaussian width=10º) Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS RHIC 1st run period s NN 130 GeV ~ 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 Henrik Tydesjö March 17 2003 5-10% 0-5% NET CHARGE FLUCTUATIONS pT , of positive and negative particles Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS Reduction not as large as predicted for QGP Consistent with resonance gas 10% most central events Global Charge Conservation Henrik Tydesjö March 17 2003 NET CHARGE FLUCTUATIONS Fluctuations independent of centrality 10% most central events: v(Q) 0.965 0.007( stat ) 0.019( syst ) Henrik Tydesjö March 17 2003 SUMMARY - 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 Henrik Tydesjö March 17 2003