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The “Extra Strong” Quark Gluon Plasma

The “Extra Strong” Quark Gluon Plasma. Outline. What is nuclear physics? From Rutherford to QCD What is a QGP? The early universe and the QCD phase diagram How do we create and detect it in the Lab? RHIC and PHENIX

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The “Extra Strong” Quark Gluon Plasma

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  1. The “Extra Strong” Quark Gluon Plasma

  2. Outline What is nuclear physics? From Rutherford to QCD What is a QGP? The early universe and the QCD phase diagram How do we create and detect it in the Lab? RHIC and PHENIX What is the experimental evidence? few slide summary of 8 years of research What are the next steps? Understand the QGP properties with new and better equipment Axel Drees

  3. Atom Nucleus + + + Proton + + + Neutron + + Massive objects bound by the “strong force” + + From Atoms to Nuclei Most of “us” is (nearly) empty space • 99.9% of the mass of atoms is contained in the nucleus • The nucleus is about 10-12 of the volume of the atom • Nuclear density 1013 times larger than density of gold 10–10 m 10 fm = 10-14 m Axel Drees

  4. Scale given by de Broglie wavelength The Dawn of the Nuclear Physics • Rutherford’s experiments (1906 to 1911) probe the structure of atoms: Ernest Rutherford Nobel prize 1908 Discovery of the nucleus inside atoms scattering pattern reveals structure of matter: mostly small angles  evenly distributed matter atomic matter beam of energetic (E ~ few MeV) or penetrating a-particles probes matter at a scale of 10-14m large angles (or transverse momentum pT)  point like scattering centers atomic matter Axel Drees

  5. + Proton Neutron + + + + + + + + + Quarks: carriers of “color” charge of strong interaction Gluons: bind together quarks Parton Structure of the Nucleons Nucleon Nucleus Parton structure of nucleons 3 quarks bound by gluons Interaction described by Quantum Chromo Dynamics Axel Drees

  6. Deep Inelastic Scattering Experiments • “Deep inelastic” electron scattering at SLAC (1966-1978) probe structure of nucleon • “Rutherford experiment with ~ 10 GeV electron beam on proton target • Resolves structures of 0.1 fm or 1/100 of nucleus size Discovery of the Parton structure inside nucleons J.I. Friedman, H.W. Kandell, R.E. Taylor Nobel prize 1990 Birth of QCD! Axel Drees

  7. QCD: Quantum Chromo Dynamics the theory of the strong force and of the interaction of quarks and gluons • perturbative QCD calculations applicable only for large momentum transfer  small coupling • for small momentum transfer  large coupling only solution numerical QCD calculations on lattice results from lattice QCD establish the QCD phase transition Critical energy eC = 62 TC4 jump in energy density: TC ~ 175 MeV eC ~ 0.3-1.0 GeV/fm3 critical temperature TC Axel Drees

  8. A New Approach? Duality of Theories that Look Different • Tool in string theory for 10 years • Strong coupling in one theory corresponds to weak coupling in other theory • AdS/CFT duality (Anti deSitter Space/ Conformal field theory) (in QCD) (N=4 SYM) Axel Drees

  9. Today’s Fundamental Puzzles Unsolved puzzles of QCD: • Confinement • Quarks do not exist as free particles • Contained inside of “hadrons” • Large nucleon masses • Each quark has the mass of 5-7 MeV/c2 ~ 1% of a nucleon (!) • The mass of protons and neutrons is “frozen energy” • Complex structure of nucleons • 3 valence quarks • Gluons • Sea quarks and anti quarks 3 quarks: baryons e.g. proton & neutron quark anti-quark: meson e.g. p pion described by measured quark and gluon density functions Axel Drees

  10. ~ 10 ms after Big Bang Hadron Synthesis strong force binds quarks and gluons in massive objects: protons, neutrons mass ~ 1 GeV/c2 ~ 100 s after Big Bang Nucleon Synthesis strong force binds protons and neutrons bind in nuclei Axel Drees

  11. ~ 10 ms after Big Bang T ~ 200 MeV Hadron Synthesis strong force binds quarks and gluons in massive objects: protons, neutrons mass ~ 1 GeV/c2 Quark Gluon Plasma High T and density QCD Planck scale T ~ 1019 GeV End of Grand Unification inflation ~ 100 ps after Big Bang T ~ 1014 GeV Electroweak Transition explicit breaking of chiral symmetry Axel Drees

  12. Study high T and r QCD in the Laboratory Quark Matter: Many new phases of matter Asymptotically free quarks & gluons Strongly coupled plasma Superconductors, CFL …. Experimental access to “high” T and moderate r region: heavy ion collisions Pioneered at SPS and AGS Ongoing program at RHIC Future program at LHC Exploring the Phase Diagram of QCD T Quark Matter Mostly uncharted territory sQGP TC~170 MeV Hadron Resonance Gas Overwhelming evidence: Strongly coupled quark matter produced at RHIC temperature Nuclear Matter baryon chemical potential 1200-1700 MeV 940 MeV mB Axel Drees

  13. Au-Au Event at RHIC summer 2001 b ~ 0 p p p K p p q J/ p p q p g p cc p e+ p p e- p p p View of a Heavy Ion Collision Au at 100 GeV/nucleon Au at 100 GeV/nucleon • Experimental probes • Thermodynamics & Collective motion • Penetrating probes • jets of particles • heavy and rare particles • thermal radiation several 1000 particles produced in central collision Axel Drees

  14. RHIC STAR PHENIX Relativistic Heavy Ion Collider at BNL • 2 counter-circulating rings • 2.4 miles circumference • 1740 super conducting magnets • Collides any nucleus on any other • Top energies: 200 GeV Au-Au 500 GeVpolarized p-p Axel Drees

  15. The PHENIX Collaboration Axel Drees

  16. University at Stony Brook: Department of Physics and Astronomy: R. Averbeck,R.Bennet, S. Campbell, C.H.Chen, Z.Citron, M.Connors, N.Cassano, A.Deshpande, A. Drees, J.M.Durham, J.Frantz, T.K. Hemmick, R. Hutter, B. Jacak, J.Kamin, M.McCumber, N.Means, M. Nguyen, V. Pantuev, R.Petti, M. Proissl, J.Sun, H.Themann, A.Toia Completed PhD Thesis: J. Burward-Hoy, S. Butsyk, K.Boyle, T. Dahms, A. Dion, J. Egdemir, S. Leckey, J. Jia, E. Matathias, A. Purwar, A. Sickels Masters Degrees: S.Abeytunge, B.Anderson, B.Azmoun, T.Dahms, L.Hammons, J. Thomas, J.Sugrim, T.H.Christ, F.Muehlbacher, C.H.Jaroschek one of the strongest university groups at RHIC The PHENIX Collaboration 14 countries 69 institutions, 489 members 21 USA 3 China 11 Japan 2 India 8 Korea 1 Brazil 6 Russia 1 Finland 5 France 1 Germany 3 Hungary 1 Israel 3 Czech 1 Sweden Axel Drees

  17. The PHENIX Experiment at RHIC • 2 central spectrometers • 2 forward spectrometers • 3 global detectors Axel Drees

  18. PHENIX Central Arms East Carriage Drift Chamber Central Magnet West Carriage Axel Drees

  19. g g DC PC1 PC2 magnetic field & tracking detectors PC3 Measuring Leading Particles in PHENIX neutral pion p0g g Calorimeter charged particle Axel Drees

  20. Strongly coupled plasma < 1 fmTi~300 MeV atenergy density 5-25 GeV/fm3 “opaque black hole” thermal radiation jet quenching J/ suppression collective expansion of fireball under pressure memory effect in hadron spectra elliptic flow confinement at phase boundary TC ~ 170 MeV in chemical equilibrium relative hadron abundance break down of chiral symmetry modification of meson (r) properties collective expansion of memory effect in hadron spectra fireball under pressure transverse flow <v/c> ~ 0.5 thermal freeze-out  > 10 fmTf = 100 MeV end of strong interactiontwo and one particle spectra Quark Matter Formation in Heavy Ion Collisions system evolutionexpectations/observations collision hard scattering jets, heavy flavor, photons Axel Drees

  21. spin isospin degeneracy baryochemical potential temperature at chemical freezeout Final State Hadrochemistry • Thermal yields hadron species • abundances in hadrochemical equilibrium • one particle ratio (e.g. p/p) determines mB/T • a second ratio (e.g. p/p) then determines T • predict all other hadron abundances and ratios final state: hadron gas close to phase boundary Axel Drees

  22. Particle Spectra • Chemical equilibrium may imply kinetic equilibrium • first guess: a thermal Boltzmann source: • However, system of interacting particles expands into vacuum • System reasonably well described by hydrodynamic evolution • Collective behavior, radial and “elliptic” flow • Use comparison of hydrodynamic calculation with data to infer input parameters Axel Drees

  23. light 1/mT dN/dmT heavy mT RHIC Spectra - an Explosive Source • different spectral shapes for particles of different mass  strong collective radial flow purely thermal source T explosive source light • reasonable agreement with hydrodynamic prediction at RHIC • Tfo ~ 100 MeV • <br> ~ 0.55 c 1/mT dN/dmT T,b heavy mT mT = (pT2 + m2)½ Full hydro calculation: Initial condition:teq ~ 0.6 fm, Ti ~ 350 MeV, e ~ 20 GeV/fm3 Axel Drees

  24. out-of-plane y Au nucleus in-plane x Au nucleus z Non-central Collisions Elliptic Flow → Early Thermalization • initial state of non-central Au+Au collision • spatial asymmetry • asymmetric pressure gradients • translates into • momentum anisotropy in final state • Fourier expansion • elliptic flow strength • shape “washes out” during expansion, i.e. elliptic flow is “self quenching” • v2 reflects early interactions and pressure gradients Liquid Li Explodes into Vacuum Axel Drees

  25. Hadron v2 and more Hydrodynamics • Observations at RHIC • v2 is large and for low momentum hadrons in good agreement with ideal hydrodynamics! • Deviations at larger pT interpreted as effects due to viscosity Early thermalization in partonic phase! Axel Drees

  26. R. Lacey et al.: PRL 98:092301, 2007 v2 PHENIX & STAR (4p) Measuring Sheer Viscosity h • H2O (at normal conditions): h/s ~ 380ћ/4p • h=<p>/s transport of momentum • Large cross section small viscosity • Gas: h/s↑ for T↑ (because <p> ↑)divergent viscosity of ideal gas • Liquid: h/s↓ for T↑ (lower T easier to transport p) •  η/s has a minimum at the critical point conjectured quantum limit AdS/CFT

  27. g g q q g g q q p p r g Black Body Radiation from Plasma?! • Direct photons • From initial hard scattering “prompt” • From medium: “thermal”, “pre-equilibrium”, other effects decays thermal hadron gas: QGP: prompt Direct contributions small (<10%) compared to hadron decay contribution  measurement limited by systematic uncertainties Axel Drees

  28. First Measurement of Thermal Radiation at RHIC • Slope analysis of data: • pQCD + exp. • Fix B, b, and n from p+p • Inverse Slope: (min. bias Au-Au) T = 224  16 (stat)  18 (sys) • Initial temperatures and times from theoretical model fits to data: • 0.15 fm/c, 590 MeV (d’Enterria et al.) • 0.2 fm/c, 450-660 MeV (Srivastava et al.) • 0.5 fm/c, 300 MeV (Alam et al.) • 0.17 fm/c, 580 MeV (Rasanen et al.) • 0.33 fm/c, 370 MeV (Turbide et al.) From data: Tini > 220 MeV > TC From models: Tini = 300 to 600 MeV t0 = 0.15 to 0.5 fm/c Axel Drees arXiv:0804.4168v1, 25 April 2008

  29. Penetrating Probes of Quark Matter • Rutherford experiment a atom discovery of nucleus SLAC electron scattering e  proton discovery of quarks QGP penetrating beam (jets or heavy particles) absorption or scattering pattern Nature provides penetrating beams or “hard probes” and the QGP in A-A collisions • Penetrating beams created by parton scattering before QGP is formed • High transverse momentum particles  jets • Heavy particles  open and hidden charm or bottom • Calibrated probes calculable in pQCD • Probe QGP created in A-A collisions as transient state after ~ 1 fm Axel Drees

  30. schematic view of jet production leading particle hadrons hadrons leading particle q q hadrons leading particle hadrons leading particle Jets: A Penetrating Probe for Dense Matter • What is a jet? • Incoming partons may carry large fraction x of beam momentum • These partons can scatter with large momentum transfer • Results in large pT of scattered partons • appears in laboratory as “jet” of particles • Jet production can be observed as • high pT leading particles • angular correlation • In a gold gold collision • Scattered partons travel through dense matter • Expected to loose a lot of their energy • Energy loss observed as • suppression of high pT leading particles • suppression of angular correlation • Depending on path length, i.e. centrality and angle to reaction plane reaction plane Axel Drees

  31. p+p Trigger particle with high pT > pT cut 1 yield/trigger 0 Df to all other particles with pT > pT cut-2  /2  0 Au+Au yield/trigger elliptic flow random background 0  /2  0 statistical background subtraction Au+Au ??? Au-Au yield/trigger suppression? 0  /2  0 Azimuthal Correlations from Jets pp jet+jet STAR Jet correlations in Au-Au via statistical background subtraction Axel Drees

  32. 0-12% STAR hydro vacuum fragmentation reaction of medium peripheral or pp central AuAu Hard Probes: Light Quark/Gluon Jets • Status • Calibrated probe • Strong medium effect • Jet quenching • Reaction of medium to probe (Mach cones, recombination, etc. ) • Matter is very opaque • Significant surface bias • Limited sensitivity to energy loss mechanism Axel Drees

  33. Mach Cones and Shock Waves in “QCD” Mostly theoretical speculations Need data with heavy quarks! Axel Drees

  34. Hard Probes: Open Heavy Flavor Electrons from c/b hadron decays • Status • Calibrated probe? • pQCD under predicts cross section by factor 2-5 • Factor 2 experimental differences in pp must be resolved • Charm follows binary scaling • Strong medium effects • Significant charm suppression • Significant charm v2 • Upper bound on viscosity ? • Little room for bottom production • Limited agreement with energy loss calculations • What is the energy loss mechanism? • What are the properties of QGP? Answers from direct charm/beauty measurements Progress limited by: no b-c separation  decay vertex with silicon vertex detectors statistics (BJ/)  increase luminosity Axel Drees

  35. FVTX Si Endcaps Nose Cone Calorimeter VTX Si Barrel PHENIX Upgrades in the Vertex Region VTX, FVTX and NCC add key measurements to RHIC program: • Heavy quark characteristics in dense medium • Charmonium spectroscopy (J/, ’ , cand ) • Light qurak/gluon energy loss through g-jet • Gluon spin structure (DG/G) through g-jet and c,b quarks • A-, pT-, x-dependence of the parton structure of nuclei Axel Drees

  36. Direct Observation of Open Charm and Beauty e,m X D Au Au D B J/ p K X e e Direct Observation of Open Charm and Beauty Detection of decay vertex will allow a clean identifications of charm and bottom decays m ct GeV mm D0 1865 125 D± 1869 317 B0 5279 464 B± 5279 496 • Heavy flavor detection with VTX and FVTX in PHENIX: • Beauty and low pT charm via displaced e and/or m -2.7<h<-1.2 , |h|<0.35 , 2.7<h<1.2 • Beauty through displaced J/  ee (mm) -2.7<h<-1.2 , |h|<0.35 , 2.7<h<1.2 • High pT charm through D   K|h|<0.35 Axel Drees

  37. PHENIX Silicon Vertex Tracking Upgrades • VTX: silicon VerTeX barrel tracker ongoing construction funded by RIKEN and DOE • 2 inner hybrid pixel layers, • Pixel sensor 50mm x 425mm, • ALICE1LHCB chip • 2 outer layers strip sensors, • single sided crossed strip design (BNL), • (80mm x 3cm), SVX4 readout chip • FVTX:Forward siliconVerTeXtracker ongoing construction funded by DOE • 2 endcaps with 4 disks each • pixel pad structure (75mm x 2.8 to 11.2 mm) • FPHX readout chip, next generation FPIX VTX barrel |h|<1.2 FVTX endcaps 1.2<|h|<2.7 mini strips Axel Drees

  38. e X D  beam DCA, distance of closest approach PHENIX Barrel VerTeX Detector • VTX characteristics • 2 inner pixel layers (50x425 mm2) to measure DCA radial position at 2.5 and 5 cm with ~ 1.3% X/X0 • 2 out strip-pixel (80x1000 mm2) for p measurement and tracking at 10 and 14 cm with ~ 3.6% X/X0 • DCA resolution: given mostly by inner layer • Sufficient single hit resolution (~15 mm) • Close to beam axis to reduce effect of multiple scattering • |h|<1.2 • ~ 2p |z| 10 cm Axel Drees

  39. Pixel Detector Layer 3 Layer 1 Layer 1 Layer 2 Layer 2 Layer 3 row col Half ladder (2 x 4chip sensor modules and bus) 13.9mm 126 mm ALICE1LHCb r/o chip pixel sensors Stripixel sensors beam resolution column : 140 (mm) row : 32 (mm) FNAL test beam August 2008 Axel Drees

  40. Stripixel Detector Stripixel @ PHENIX Size : 3.5×6.4 cm2 Thickness : 625mm #channel : 1,536 Strip-pixel size : 80×1000 mm2 DC coupled readout to SVX4 readout chip Sensor elements: Pixels: 80 µm 1 mm, projective readout via double metal XU/V “strips” of ~3 cm length. Single-sided sensor with 2D charge sharing SVX4 NIMA518, 738 (2004). sensor MIP peak from beam U-projection X-projection signal/noise ~ 10:1 Axel Drees

  41. Dilepton Continuum at RHIC • Status • Low mass enhancement (150-750 MeV) • Connected to Chiral Symmetry restoration?? • Soft pt component Teff ~ 100 MeV • Both features qualitatively consistent with CERN experiments • No quantitative theoretical explanation • Open experimental issues: • Large combinatorial background prohibits precision measurements in low mass region! • Disentangle charm and thermal contribution in intermediate mass region! Need tools to reject photon conversions and Dalitz decays and to identify open charm PHENIX  hadron blind detector (HBD) vertex tracking (VTX) Axel Drees

  42. Key Issue: Combinatorial Background • Photon conversions & Dalitz decays • e- or e+ in acceptance & pT> 200 MeV • partner is not • Identify partner and • veto pair, exclude it from • further combinations Axel Drees

  43. signal electron e- partner positron needed for rejection Cherenkov blobs e+ qpair opening angle ~ 1 m A Hadron Blind Detector (HBD) for PHENIX • Dalitz & Conversion rejection via opening angle • Identify electrons in field free region • Veto signal electrons with partner • HBD concept: • windowless CF4 Cherenkov detector • 50 cm radiator length • CsI reflective photocathode • Triple GEM with pad readout • Reverse bias (to get rid of ionization electrons in the radiator gas) • Status • V1 installed and took data in 2007 • Proof of principle, but operation not stable • V2 (almost) ready for installation • Physics data with pp at 200 GeV in 2009 • AuAu data at 200 GeV in 2010 Axel Drees

  44. Timeline of PHENIX Upgrades 2010 2012 2014 2008 RHIC Stochastic cooling “RHIC II” AuAu dileptons HBD Displaced vertex at mid rapidity VTX Large acceptance tracking |Dh|<1.2 m Trigger W - physics Displaced vertex at forward y FVTX NCC Construction Physics Axel Drees

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