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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 - QGP Signals 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 - QGP Signals Event-by-Event Net-Charge Fluctuations Simulations PHENIX Analysis Henrik Tydesjö May 5 2004

  3. Phase Diagram of Nuclear Matter Early Universe Ultra-Relativistic Heavy-Ion Collisions ??? QGP Hadron Gas Neutron Stars ??? Henrik Tydesjö May 5 2004

  4. DECONFINEMENT PHASE TRANSITION QUARKGLUONPLASMA Henrik Tydesjö May 5 2004

  5. QUARKGLUONPLASMA CHIRAL SYMMETRY RESTORATION Quark Masses 0 Henrik Tydesjö May 5 2004

  6. Relativistic Heavy Ion Collider (RHIC) Au+Au Collisions 100 AGeV per beam Henrik Tydesjö May 5 2004

  7. Collaboration ~ 460 Members 57 Institutions 12 Countries Henrik Tydesjö May 5 2004

  8. Central Magnet Beam-Beam Counters Muon Arm Spectrometers Central Arm Spectrometers Henrik Tydesjö May 5 2004

  9. Central Arms Charged Particle Tracking Electron, Photon Detection Hadron Identification Pad Chambers Henrik Tydesjö May 5 2004

  10. Pad Chambers • - Multi-Wire Proportional Chambers • - Fine Granularity Pixel Pad Readout • - Provide Space Points for • Track Recognition Henrik Tydesjö May 5 2004

  11. 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 May 5 2004

  12. Event Display Central Au+Au Collision ~ 400 tracks in central arms Henrik Tydesjö May 5 2004

  13. QGP SIGNALS • Jet Quenching • J/Y Suppression • - Strangeness enhancement • Thermal photon production • Light vector meson decays • - Fluctuation probes Henrik Tydesjö May 5 2004

  14. QGP SIGNALS • Jet Quenching • J/Y Suppression • - Strangeness enhancement • Thermal photon production • Light vector meson decays • - Fluctuation probes Henrik Tydesjö May 5 2004

  15. QGP SIGNALS • Jet Quenching • J/Y Suppression • - Strangeness enhancement • Thermal photon production • Light vector meson decays • - Fluctuation probes Henrik Tydesjö May 5 2004

  16. 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 May 5 2004

  17. NET CHARGE FLUCTUATIONS QGP HADRON GAS charge more evenly spread in plasma, due to the fractional charges of quarks Henrik Tydesjö May 5 2004

  18. NET CHARGE FLUCTUATIONS Random Particle Emission: Charge q in each event: Normalized Variance: Variance of q: Henrik Tydesjö May 5 2004

  19. NET CHARGE FLUCTUATIONS Hadron Gas : QGP (assuming thermal distributions) : Hadronized QGP (from theorist calculation) : BUT HEY!!! WAIT A MINUTE!!! Wouldn’t this depend very much on acceptance? Henrik Tydesjö May 5 2004

  20. NET CHARGE FLUCTUATIONS SIMULATION Charge is globally conserved Henrik Tydesjö May 5 2004

  21. NET CHARGE FLUCTUATIONS SIMULATION Efficiency Dependence Henrik Tydesjö May 5 2004

  22. NET CHARGE FLUCTUATIONS SIMULATION Uncorrelated Background Contribution Henrik Tydesjö May 5 2004

  23. NET CHARGE FLUCTUATIONS SIMULATION Decays of Neutral Resonances (e.g.  , )introduce positive correlations between n+ and n– width= 30º Henrik Tydesjö May 5 2004

  24. NET CHARGE FLUCTUATIONS SIMULATION Decays of Neutral Resonances fres = 0.3 Henrik Tydesjö May 5 2004

  25. NET CHARGE FLUCTUATIONS SIMULATION Simple QGP model: producing 2 or 3 pions, separated in azimuth (Gaussian width=10º) Henrik Tydesjö May 5 2004

  26. NET CHARGE FLUCTUATIONS RHIC 1st run period ~ 500 000 events |zvertex| < 17 cm pT > 200 MeV/c Henrik Tydesjö May 5 2004

  27. Centrality of Collision b Impact parameter, b < 10 fm ~ Henrik Tydesjö May 5 2004

  28. 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 May 5 2004

  29. NET CHARGE FLUCTUATIONS pT ,  ofpositiveandnegative particles Henrik Tydesjö May 5 2004

  30. NET CHARGE FLUCTUATIONS Global Charge Conservation Reduction not as large as predicted for QGP Consistent with resonance gas 10% most central events Henrik Tydesjö May 5 2004

  31. NET CHARGE FLUCTUATIONS Fluctuations independent of centrality 10% most central events: Henrik Tydesjö May 5 2004

  32. 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 May 5 2004

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