2. Henrik Tydesjö March 17 2003 O UTLINE - The Quark Gluon Plasma - The Relativistic Heavy Ion Collider (RHIC) - The PHENIX Experiment - Event-by-Event Net-Charge Fluctuations Simulations PHENIX Analysis

3. Henrik Tydesjö March 17 2003 Q UARK G LUON P LASMA At extremely High Densities & Temperatures Nuclear Matter may undergo a Phase Transition to a state called the Quark Gluon Plasma (QGP)

4. Henrik Tydesjö March 17 2003 Q UARK G LUON P LASMA D ECONFINEMENT PHASE TRANSITION

5. Henrik Tydesjö March 17 2003 Q UARK G LUON P LASMA C HIRAL S YMMETRY R ESTORATION C HIRAL S YMMETRY R ESTORATION Quark Masses 0

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

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

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

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

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

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

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

13. 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)

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

15. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS 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

16. Henrik Tydesjö March 17 2003 Hadronization ??? Pion Gas QGP N ET C HARGE F LUCTUATIONS +  1/3 +  2/3 +  1

17. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS Charge Q in each event: Variance of Q: Random Particle Emission: Normalized Variance:

18. Henrik Tydesjö March 17 2003  1000 particles per event  assigned: charge +1 or –1, azimuthal angle  N ET C HARGE F LUCTUATIONS SIMULATION

19. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS SIMULATION Charge is globally conserved

20. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS SIMULATION Efficiency Dependence

21. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS SIMULATION Uncorrelated Background Contribution

22. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS SIMULATION Decays of Neutral Resonances (e.g. ,  ) introduce positive correlations between n + and n –  width = 30º

23. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS SIMULATION Decays of Neutral Resonances f res = 0.3

24. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS SIMULATION Simple QGP model: producing 2 or 3 pions, separated in azimuth (Gaussian width=10º)

25. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS RHIC 1 st run period ~ 500 000 events |z vertex | < 17 cm p T > 200 MeV/c

26. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS BBCs used for triggering corresponding to 92% of inelastic cross-section Centrality classes determined from BBC+ZDC information 0-5% 5-10%

27. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS p T,  of positive and negative particles

28. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS Reduction not as large as predicted for QGP Consistent with resonance gas Global Charge Conservation 10% most central events

29. Henrik Tydesjö March 17 2003 N ET C HARGE F LUCTUATIONS Fluctuations independent of centrality 10% most central events:

30. Henrik Tydesjö March 17 2003 S UMMARY - 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

31. Henrik Tydesjö March 17 2003