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Motivation

Motivation. Collaboration. EllipticFlow Measurements with PHENIX. I N T E R N A T I O N A L   W O R K S H O P O N   T H E    P H Y S I C S   O F T H E    Q U A R K   -     G L U O N     P L A S M A. Roy A. Lacey (SUNY Stony Brook) PHENIX Collaboration. Motivation.

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Motivation

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  1. Motivation Collaboration

  2. EllipticFlow Measurements with PHENIX I N T E R N A T I O N A L   W O R K S H O P O N   T H E    P H Y S I C S   O F T H E    Q U A R K   -    G L U O N    P L A S M A Roy A. Lacey (SUNY Stony Brook) PHENIX Collaboration

  3. Motivation The Notion of an EOS /Phase Transitions is Pervasive

  4. Motivation Which Observable Provides an Important Opportunity to Probe the EOS and QGP Formation ? Elliptic Flow (Differential Elliptic Flow)

  5. Low Energy: ---- Squeeze-out High Energy : In-plane Emission Elliptic Flow Azimuthal Asymmetry in the Flow of Particle Momentum or Energy

  6. Elliptic Flow The Transition from Negative to Positive Elliptic Flow Occurs ~ 4 AGeV

  7. Elliptic Flow d1 d2 • The Driving Forces for Elliptic Flow are Understood • Differential Elliptic Flow Studies are Important

  8. PHENIX 2% Central ~ 4.6 GeV/fm3 RHIC ? • Significant Variation in the Energy Density Variations~ x 3 Lattice Calculations - Phase Transition ~ 1 GeV/fm3 A Wide Range Energy Densities are Accessible at RHIC

  9. Differential Elliptic Flow Sorge The onset of QGP provides a Characteristic Signal

  10. Analysis • Study Correlation • between particles: • Event by event reaction plane determination & Dispersion Corrections Circumvented • Uncertainties associated with Acceptance, efficiencyReduced Smaller Signal !!

  11. Correlation Function Wang et al., PRC 44, 1091 (1991) Lacey et al. PRL 70, 1224 (1993) Good Signal to Noise

  12. “Spectators” 15-20% “Participants” 10-15% 5-10% “Spectators” 0-5 % Centrality Selection .

  13. Correlation Functions • Anisotropy Shows Clear CentralityAnd pT Dependence • Viable Method

  14. Differential Flow (pt , cent) PHENIX Preliminary Strong pt Dependence

  15. Differential Flow (pt) STAR PHENIX Reasonable Agreement Between Experiments

  16. Huovinen QM01 Strong Velocity Field Required for pt dependence Differential Flow (pt) What Does the pT Dependence Tell You ?

  17. E895 Rapidity Dependence due to Sidewards Flow Differential Flow ( ) PHOBOS Extensive Pseudorapidity reach by PHOBOS

  18. For large pseudorapidity -- Thermalization ? Longitudinal expansion ? Differential Flow ( ) Hirano et al.

  19. Separate effects Of pT and Centrality (Scaled Elliptic Flow) Spatial Asymmetry  Momentum Asymmetry Compatible with Rapid Thermalization Differential Flow (cent, pt ) • Sizeable Centrality Dependence • Pt cuts enhance the centrality dependence

  20. Differential Elliptic Flow Sorge The onset of QGP provides a Characteristic Signal

  21. Scaled Differential Flow (cent, pt ) High pT probe earlier Times and Larger Energy Densities ?? Scaled Elliptic Flow Suggestive !!

  22. Summary Flow Measurements can serve as an important probe of Nuclear Matter at high energy density • At RHIC • Sizeable Integral and Differential Elliptic flow Observed • Separate Effects of Geometry and Dynamics can be Identified • pT dependence – strong velocity fields • cent dependence – Rapid Thermalization • Rapidity dependence – Energy Density profile ?? • Scaling for low pT particles • Larger Flow for central collisions for High pT hadrons -- Mixed Phase for mid-central collisions ?? Exciting and Interesting Work Lay Ahead

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