Chester - Sept Russell Betts 1 The Experimental Challenge Adapting the Techniques of Particle Physics to Measuring 100  more Particles per Collision Central Au+Au Event at 200GeV/u

Chester - Sept Russell Betts 2 Tracking in B-Field Tracking of Particles Wire Chambers Time Projection Chambers Silicon Pad/Strip Detectors

Chester - Sept Russell Betts 3 Tracking and Calorimeters

Chester - Sept Russell Betts 4 Particle ID dE/dx – Bethe Bloch- also in “Relativistic Rise” Time-of-Flight Cerenkov (  Filter) RICH Counters etc Momentum (GeV/c) dE/dx (a.u.) ++ ++ K++K–K++K– p+p Stopping Particles Relativistic Rise

Chester - Sept Russell Betts 5 Particle ID (II) M(K +  - ) (GeV/c 2 ) Entries M inv Reconstruction eg  0, K*…. J/ ,  from  Displaced Vertex for Long-Lived Particles

Chester - Sept Russell Betts 6 The RHIC Facility Two rings of Superconducting Magnets ( 2.4 mi circ) Ions of Au Accelerated up to 100 GeV/u also Cu, d and Polarized p. Six Intersections, Four Experiments - BRAHMS, PHOBOS, PHENIX and STAR

Chester - Sept Russell Betts 7 Broad Range Hadron Magnetic Spectrometer 2 Spectrometers Magnets, Tracking Chambers, TOF, RICH Inclusive particle production over a large rapidity and p T range

Chester - Sept Russell Betts 8 Broad Range Hadron Magnetic Spectrometer

Chester - Sept Russell Betts 9 Brahms – Mid Rapidity Region

Chester - Sept Russell Betts 10 PHENIX Axial Field High Resolution & Rates 2 Central Arms 2 Forward Arms TEC RICH EM Cal Si TOF  -ID

Chester - Sept Russell Betts 11 PHENIX Leptons, Photons, and Hadrons in selected solid angles (especially muons)

Chester - Sept Russell Betts 12 PHENIX + Collaboration

Chester - Sept Russell Betts 13 STAR Solenoidal field Large Solid Angle Tracking TPC’s Si-Vertex Tracking RICH EM Cal TOF Measurements of Hadronic observables using a large acceptance spectrometer Event-by-event analyses of global observables, hadronic spectra and jets

Chester - Sept Russell Betts 14 STAR MagnetCoilsCentralTriggerBarrel(CTB)ZCalTimeProjectionChamber(TPC) Year 2000 Barrel EM Cal (BEMC) Silicon Vertex Tracker (SVT) Silicon Strip Detector (SSD) FTPC Endcap EM Cal FPD TOFp, TOFr FPD Year PMD

Chester - Sept Russell Betts 15 STAR + Collaboration

Chester - Sept Russell Betts 16 PHOBOS Spectrometer Paddle Trigger Counter NIM A 499 (2003) 603 Octagon TOF SpecTrig T0 counter 44-  Multiplicity Detector MMagnetic Spectrometer + TOF

Chester - Sept Russell Betts 17 First Look at “Virtual” Reality

Chester - Sept Russell Betts 18 PHOBOS Trigger Counters Cherenkov Counters (548 cm) Paddle Counters (321 cm) IR ZCAL (18.5m)

Chester - Sept Russell Betts 19 PHOBOS - Multiplicity

Chester - Sept Russell Betts 20 PHOBOS - Spectrometer

Chester - Sept Russell Betts 21 PHOBOS – Time of Flight

Chester - Sept Russell Betts 22 Triggering on Collisions Negative Paddles Positive Paddles ZDC NZDC P Au x z  t (ns) Events Valid Collision 13:01 6/13/2000

Chester - Sept Russell Betts 23 Centrality Determination Spectators Participants

Chester - Sept Russell Betts 24 Paddle Mean N Part N Part and N Coll

Chester - Sept Russell Betts 25 Finding the Vertex High ResolutionLow Resolution Vertex Detector

Chester - Sept Russell Betts 26 Charged Particle Multiplicity Predictions Prior to RHIC Data From Counting Hits

Chester - Sept Russell Betts 27 P T Spectrum (Linear) Bulk of Particles p T <1GeV

Chester - Sept Russell Betts 28 Compiled Data on Spectra

Chester - Sept Russell Betts 29 Energy per Unit Volume Initially released Energy per Unit Volume  5 GeV/fm 3 Note: Energy Density inside Proton ≈ 0.5 GeV/fm 3 Therefore Total Energy Released in |  | < 1 is ~2000GeV Energy of Collision “ Relevant” Initial Volume ~  R 2  ( 1 fm)  2 ~ 0.7 GeV Number of Particles Produced at y=0 dN ch /d 

Chester - Sept Russell Betts 30 Baryon Density

Chester - Sept Russell Betts 31 Particle Ratios,Thermal Model Fit

Chester - Sept Russell Betts 32 Data on the Phase Diagram Baryonic Potential  B [MeV] Chemical Temperature Tch [MeV] AGS SIS SPS RHIC quarks-gluons hadrons Thermal Model of Ratios  B = 45 MeV Assuming T=165 MeV Redlich et al Phase Diagram (N Xu)

Chester - Sept Russell Betts 33 Elliptical Flow dN/d(  R ) = N 0 (1 + 2V 1 cos (  R ) + 2V 2 cos (2(  R )) +... ) b (reaction plane) Look at emission patterns using Fourier expansion: extract V 2 components from the fits. “head on” view of colliding nuclei y x 

Chester - Sept Russell Betts 34 Elliptical Flow 200 GeV Au+Au PHOBOS preliminary 0 <  < % central, h + + h - Approaches Hydrodynamical Limit (Zero Mean Free Path)

Chester - Sept Russell Betts 35 Energy Dependence of Flow Reaction plane x z y Hydrodynamic Limit of Flow at RHIC Strongly Interacting Fluid sQGP wQGP

Chester - Sept Russell Betts 36 Scaling of Flow with n q

Chester - Sept Russell Betts 37 Low Energy Particles In a large volume, weakly interacting system we would expect the development of particles with long wavelength PHOBOS PHENIX

Chester - Sept Russell Betts 38 E GeV Au+Au BRAHMS prel. NA GeV Au+Au 4.1 GeV Au+Au 8.8 GeV Pb+Pb 17.3 GeV Pb+Pb 200 GeV Au+Au No Longitudinal Scaling PHOBOS Plateau in Pseudorapidity Distributions is Misleading Rapidity Distributions of Pions are Gaussian

Chester - Sept Russell Betts 39 No Longitudinal Scaling (II)

Chester - Sept Russell Betts 40 High P T Suppression Suppression of High p T Particles Relative to pp – Scaled to N Coll

Chester - Sept Russell Betts 41 Suppression in Central Collisions

Chester - Sept Russell Betts 42 Comparison to d+Au

Chester - Sept Russell Betts 43 Back-to-Back Correlations qq  jet-jet

Chester - Sept Russell Betts 44 Geometry Dependence Correlation Relative to Geometry Defined by Flow

Chester - Sept Russell Betts 45 The State of Play The Energy Density is High (3-5 GeV/fm 3 ) Much Larger than Inside a Hadron Description in Terms of Hadronic Degrees of Freedom is Inappropriate The System is Strongly Interacting at Early Times (  2fm/c) Originally expected boost-invariance in mid-rapidity region not observed. There is a very large energy-loss of struck partons A New Form of Matter THE STRONGLY INTERACTING QUARK-GLUON PLASMA BUT !!!! No Direct Evidence of Color Degrees of Freedom or of Deconfinement

Chester - Sept Russell Betts 46 High Energy Limit of QCD Universal Form of Matter at High Energy Color Glass Condensate (CGC) Color Glass Condensate (CGC) Gluons have “color” High density ! occupation number ~ 1/  s at saturation High density ! occupation number ~ 1/  s at saturation created from “frozen” random color source, that evolves slowly compared to natural time scale Higher Energy Dilute Gas CGC High Density Gluons Dominant at Very Low x – High Rapidity

Chester - Sept Russell Betts 47 d+Au at Forward Angles h-h- (h - +h + )/2