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Net Charge Fluctuations in Ultra-Relativistic Nucleus-Nucleus Collisions

Net Charge Fluctuations in Ultra-Relativistic Nucleus-Nucleus Collisions. Henrik Tydesjö. O UTLINE. - The Quark Gluon Plasma - The Relativistic Heavy Ion Collider (RHIC) - The PHENIX Experiment - Event-by-Event Net-Charge Fluctuations Simulations PHENIX Analysis.

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Net Charge Fluctuations in Ultra-Relativistic Nucleus-Nucleus Collisions

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  1. Net Charge Fluctuations in Ultra-Relativistic Nucleus-Nucleus Collisions Henrik Tydesjö

  2. 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

  3. QUARKGLUONPLASMA 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

  4. DECONFINEMENT PHASE TRANSITION QUARKGLUONPLASMA Henrik Tydesjö March 17 2003

  5. QUARKGLUONPLASMA CHIRAL SYMMETRY RESTORATION Quark Masses 0 Henrik Tydesjö March 17 2003

  6. Phase Diagram of Nuclear Matter Early Universe Ultra-Relativistic Heavy-Ion Collisions ??? QGP Hadron Gas Neutron Stars ??? Henrik Tydesjö March 17 2003

  7. Relativistic Heavy Ion Collider (RHIC) Brookhaven, Long Island, New York Henrik Tydesjö March 17 2003

  8. Relativistic Heavy Ion Collider (RHIC) Au+Au Collisions 100 AGeV per beam Henrik Tydesjö March 17 2003

  9. Collaboration ~ 460 Members 57 Institutions 12 Countries Henrik Tydesjö March 17 2003

  10. Central Magnet Beam-Beam Counters Muon Arm Spectrometers Central Arm Spectrometers Henrik Tydesjö March 17 2003

  11. Central Arms Charged Particle Tracking Electron, Photon Detection Hadron Identification Pad Chambers Henrik Tydesjö March 17 2003

  12. Pad Chambers • - Multi-Wire Proportional Chambers • - Fine Granularity Pixel Pad Readout • - Provide Space Points for • Track Recognition Henrik Tydesjö March 17 2003

  13. Readout Card (ROC) • - 172,800 Readout Channels • - Chip-On-Board Technique • Readout Cards (ROCS) • Placed on the Chambers • - Data Transfer via • Fiber Optic Links Pad Chambers • - Multi-Wire Proportional Chambers • - Fine Granularity Pixel Pad Readout • - Provide Space Points for • Track Recognition Henrik Tydesjö March 17 2003

  14. Event Display Central Au+Au Collision 370 global tracks Henrik Tydesjö March 17 2003

  15. NET CHARGE FLUCTUATIONS Event-by-Event Net Charge Fluctuationsin 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

  16. NET CHARGE FLUCTUATIONS + + + 1/3 2/3 1    Hadronization ??? QGP Pion Gas Henrik Tydesjö March 17 2003

  17. NET CHARGE FLUCTUATIONS Charge Q in each event: Random Particle Emission: Normalized Variance: Variance of Q: Henrik Tydesjö March 17 2003

  18. NET CHARGE FLUCTUATIONS SIMULATION • 1000 particles per event • assigned: charge +1 or –1 , • azimuthal angle  Henrik Tydesjö March 17 2003

  19. NET CHARGE FLUCTUATIONS SIMULATION Charge is globally conserved Henrik Tydesjö March 17 2003

  20. NET CHARGE FLUCTUATIONS SIMULATION Efficiency Dependence Henrik Tydesjö March 17 2003

  21. NET CHARGE FLUCTUATIONS SIMULATION Uncorrelated Background Contribution Henrik Tydesjö March 17 2003

  22. NET CHARGE FLUCTUATIONS SIMULATION Decays of Neutral Resonances (e.g.  , )introduce positive correlations between n+ and n– width= 30º Henrik Tydesjö March 17 2003

  23. NET CHARGE FLUCTUATIONS SIMULATION Decays of Neutral Resonances fres = 0.3 Henrik Tydesjö March 17 2003

  24. NET CHARGE FLUCTUATIONS SIMULATION Simple QGP model: producing 2 or 3 pions, separated in azimuth (Gaussian width=10º) Henrik Tydesjö March 17 2003

  25. NET CHARGE FLUCTUATIONS RHIC 1st run period ~ 500 000 events |zvertex| < 17 cm pT > 200 MeV/c Henrik Tydesjö March 17 2003

  26. NET CHARGE FLUCTUATIONS BBCs used for triggering corresponding to 92% of inelastic cross-section Centrality classes determined from BBC+ZDC information 5-10% 0-5% Henrik Tydesjö March 17 2003

  27. NET CHARGE FLUCTUATIONS pT ,  ofpositiveandnegative particles Henrik Tydesjö March 17 2003

  28. NET CHARGE FLUCTUATIONS 10% most central events Global Charge Conservation Reduction not as large as predicted for QGP Consistent with resonance gas Henrik Tydesjö March 17 2003

  29. NET CHARGE FLUCTUATIONS Fluctuations independent of centrality 10% most central events: Henrik Tydesjö March 17 2003

  30. 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

  31. Henrik Tydesjö March 17 2003

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