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Introduction to relativistic heavy ion collisions

High-energy nuclear experiments Practice of color. Quantum Chromodynamics Theory of color. Introduction to relativistic heavy ion collisions. Zhangbu Xu 许长补 (BNL). 教材. 相对论重离子碰撞物理导论 --- 黄卓然 Introduction to High-Energy Heavy-ion Collisions --- Cheuk-Yin Wong (Oak Ridge)

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Introduction to relativistic heavy ion collisions

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  1. High-energy nuclear experiments Practice of color Quantum ChromodynamicsTheory of color Introduction to relativistic heavy ion collisions Zhangbu Xu 许长补 (BNL)

  2. 教材 • 相对论重离子碰撞物理导论 --- 黄卓然Introduction to High-Energy Heavy-ion Collisions --- Cheuk-Yin Wong (Oak Ridge) • STAR and PHENIX Beam Use Requests (run10 BUR) and presentations to BNL Nuclear and Particle Program Advisory Committee (PAC) in 2009 • RHIC whitepapers summarized first three-years’ discoveries: • Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC CollisionsNucl. Phys. A 757 (2005) 102; e-Print Archives (nucl-ex/0501009) • Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration.Nucl.Phys.A757:184-283,2005; e-Print: nucl-ex/0410003 • Quark gluon plasma and color glass condensate at RHIC? The Perspective from the BRAHMS experiment.Nucl.Phys.A757:1-27,2005. e-Print: nucl-ex/0410020 • The PHOBOS perspective on discoveries at RHIC.Nucl.Phys.A757:28-101,2005. e-Print: nucl-ex/0410022 • LHC: ALICE, ATLAS, CMS • Heavy Ion Collisions at the LHC - Last Call for Predictions.J.Phys.G35:054001,2008. e-Print: arXiv:0711.0974 [hep-ph] • ALICE: Physics performance report, volume I, II.J.Phys.G30:1517-1763,2004; J.Phys.G32:1295-2040,2006 • International Conferences of Quark Matter (proceedings, talks) 办公室: 306 (陈宏芳教授）；唐泽波：410

  3. Introduction Jet Quenching Initial Conditions Hydrodynamics and Thermalization Heavy Flavor Color-Screening Dilepton Proton Spin RHIC Machine Complex Search for Exotic Particles and phenomena Correlation and fluctuations: search for critical behavior Detector, and R&D Detector overview Time Projection Chamber Time-of-Flight Heavy Flavor Tracker STAR Upgrades Future frontiers Outline of the lecture series

  4. Schedule

  5. Schedule

  6. Outline • Introduction to theory of color (strong force) • Selected experimental studies of strongly interacting color medium – • Perfect Liquid • Introduce terms and methods • Exploring the properties with flavor and color via identified particles • Color charge • Future prospects -- Detector upgrades necessary

  7. Strong force – one of the four in nature • GravityMakes apple fall to ground • (3.) Electromagnetic+weak (2 unified forces) Bonds atoms together; Makes apple red and tasty • 4. Strong forceGenerates 98% of apple’s mass

  8. Structure of an atom • Where is the strong force most relevant? Atomnucleusproton/neutronquarks/gluons 10-10m 10-14m 10-15m (1fm) <10-19m

  9. Theory of strong force QuantumChromodynamics charge: color (r,b,g) 3 constituents: quark mediator: gluon Electromagnetic force 1 lepton, quark, etc photon photon: no charge Quark: ONE color charge Gluon: TWO color charges Ordinary hadrons are color neutral particles-- Mesons: 2 quarks (r+rbar) Baryons: 3 quarks (r+b+g) Three quarks for Muster Mark! James Joyce. Finnegan's Wake

  10. pion pion Anti-quark quark proton proton neutron neutron Asymptotic Freedom and Origin of Mass 渐进自由和质量产生 • Peculiar theory of color -- • weak at large momentum and short distance • Confined禁锢– required energy grows with distance • no FREE quark or gluon, fragment to “jet”– cluster of color-neutral particles • Generate most of the mass of visible world (m=E/c2) jet LEP at CERN 喷注 F. Wilczek, H.D. Politzer, and D.J. Gross, 1973; Nobel Prize 2004

  11. Energy Density/T4 (释放夸克和胶子) Free the quarks and gluons • … our vacuum, though Lorentz invariant, to be quite complicated. Like any other physical medium, it can carry long-range-order parameters and it may also undergo phase transitions… • The experimental method to alter the properties of the vacuum may be called vacuum engineering. An effective way may well be to use relativistic heavy ions. Quark-Gluon Plasma (Liquid) 加热真空达到相变的工程 T.D. Lee 1974 1957 Nobel Prize winner

  12. RHIC TIME Little Big Bang

  13. Units and dimensions Temperature: 160MeV (trillion 0C) System size: 10fm (10-12cm) Lifetime: 10fm/c (10-22s) Particles#: thousands Au: 79 protons + 118 neutronsNumber of Participant nucleons Size of a proton: 1fm Proton mass: 1 GeV/c2 Time: 1fm/c MeV = 1 million electron volt; GeV = 1 billion electron volt

  14. In the rest of my talk • Introduction to theory of color (strong force) • Selected experimental studies of strongly interacting color medium – • Perfect Liquid • Introduce terms and methods • Exploring the properties with flavor and color via identified particles • Color charge • Future prospects -- Detector upgrades necessary (RHIC II)

  15. Four Detectors 1200 Physicists 120 PhD theses Publications: topcite 50+ (72), 100+ (38), 250+ (9) CDF+D0 9 LEP 15

  16. Event in real detectors e+e-: tens of tracks, jet structure A+A: thousands of tracks, isotropic, 4m

  17. 中心对撞 质心能量=9.2 GeV 偏心对撞

  18. Models prior to RHIC CGC: high density gluons Dilute gas Physics Today, Ludlam/McLerran momentum Color Glass Condensate Simple Counting Initial condition: high density gluons DIS: ep, eA (eRHIC)

  19. Energy Density/T4 Study phase transition, 101 Energy Density and Temperature • Count particles • Energy • System size • Phase boundary: 1 GeV/fm3 • Normal nuclear density0.16GeV/fm3 • Equilibration time • Temperature What we need to know then are:

  20. STAR whitepaper Temperature from Chemistry among hadrons • Statistical Mechanics describes the relative particle abundances • This happens at the phase boundary (T=165+-10MeV) 强子的热统分布: 温度和化学势

  21. Critical Temperature is not ONE number

  22. Baryon Density QCD Phase Diagram

  23. Sensitive to equilibration time • Ideal hydrodynamics describes the anisotropic flow • Liquid-like matter • Strong coupling; • Surprisingly Fast equilibrium(<<1fm); • low viscosity 粘度 (shear 剪切, bulk 体积) important theoretical implication RHIC animations and multimedia: http://www.phenix.bnl.gov/WWW/software/luxor/ani/

  24. Jet Quenching 喷注淬灭 • Another probe of early stage • Energetic quarks/gluons traverse QGP, they radiate soft gluons and lose energy • Reduce the abundance of high momentum particles and their correlations

  25. Experimental and Theoretical Challenges in the Search for the Quark Gluon PlasmaThe STAR Collaboration’s Critical Assessment of the Evidence from RHIC Collisions, Nucl. Phys. A 757 (2005) 102 Strong evidences pointing to a “dense, opaque, low-viscous, pre-hadronic liquid state of matter not anticipated before RHIC” Study the properties of this matter. What are the critical needs from future Experiments (STAR White paper)?

  26. H2O Connections to other fields Phys.Rev.Lett.94:111601,2005; Phys.Rev.Lett.97:152303,2006 http://www.bnl.gov/rhic/blackHoles2.asp Black Hole, String Theory universal low viscosity limit 1/4p? • Low-temperature Atomic Physics • EOS of Neutron stars • Strong field condensed • matter physics of QCD Big Bang

  27. In the rest of my talk • Introduction to theory of color (strong force) • Selected experimental studies of strongly interacting color medium – • Perfect Liquid • Introduce terms and methods • Exploring the properties with flavor and color via identified particles • Color charge • Future prospects -- Detector upgrades necessary (RHIC II)

  28. Color factor (gluon and quark)? Quark: ONEcolor charge => pion Gluon: TWOcolor charges => proton Difference between gluon and quark jet quenching Need good hadron identification at very high transverse momentum

  29. Quark vs gluon from hadron suppression STAR, B. Mohanty STAR, L. Ruan Curves: X-N. Wang et al PRC70(2004) 031901 PRL 97, 152301 (2006) pT (GeV/c) No sign of stronger gluon energy loss in p/p or p/p ratios X.N. Wang and X.F. Guo, NPA 696, 788 (2001) W. Liu, C.M. Ko, B.W. Zhang, nucl-th/0607047 强子压底 Need good understanding of how quarks and gluons turn into hadrons

  30. Is Color charge a factor? • QCD Models: gluon, light quark and heavy quark lose different amount of energy • Experimental results so far do notgpbar, u/d p, c  e • Jet Quenching picture works • Something interesting happens Strongly interacting (radiational+collisional) • Future investigations

  31. In the rest of my talk • Introduction to theory of color (strong force) • Selected experimental studies of strongly interacting color medium – • Perfect Liquid • Introduce terms and methods • Exploring the properties with flavor and color via identified particles • Color charge • Future prospects -- Detector upgrades necessary (RHIC II)

  32. Thermometers: dilepton, photon Color Screen: heavy quarkonium species. Upgrades for STAR experiments Near/Long Term: STAR white paper Nucl. Phys. A 757 (2005) 102

  33. 强相互作用相图 QCD Phase Diagram • Can we put a point above? Exp(-e/T) • Can we study the mass structure directly (chiral symmetry restoration) • Electron, Muon, photon, heavy quarks • Rare probes need high luminosity

  34. K- p+ Brownian motion of Heavy quarks 重味夸克的布朗运动 • Charm quarks m ~ 1200 MeVT ~ 165 MeV • “drag” and diffusion of “solid” object • Direct Reconstruction • Elliptic flow • Spectra 测QGP阻力和扩散系数

  35. Color Screening of heavy quarks 重味夸克介子的色屏蔽:QGP温度和相关长度 • J / suppression J /+- (e+e-) • Different states predicted to melt at different T in color medium (Td/Tc) • Charmonia(J/), bottomonia () • Coalescence of charm Quarkonium dissociation temperatures – Digal, Karsch, Satz Active program at PHENIX, STAR, SPS

  36. STAR Upgrades Muon Detector Time Of Flight

  37. 时间投影室 Identify particles by TPC 带电粒子的电离能损随动量变化 Time Projection Chamber (TPC): 45 padrow, 4 meters (diameter) Magnetic field: 0.5Tesla

  38. Identify particles by TPC + TOF Time-of-Flight (TOF): 1 tray (~1/200, prototype), s(t)=85ps m2 = p2/(1/b2-1), b=l/t

  39. STAR Time-of-Flight Multi-gap Resistive Plate Chamber New technology, Cost-effective Hadron PID, electron PID Time-of-Flight Module 4000 of them Project supported by DOE(US) & NSFC, MST,CAS(China)

  40. Novel & Compact Muon Detector for QCDLab • Novel and Compact -------- ConventionTiming, Position  Track Segments+FastHits • Muon is penetrating probe • QCDLab (RHIC II, eRHIC) • Works with Accelerator High Luminosity upgrades A BNL 2007 LDRD project

  41. Hadron Rejection and Muon Trigger at STAR • Muon penetrates iron bars • Other particles are stopped • Good Time Resolution (60ps) rejects background (>100) • 1 hit per 5 head-on Au+Au • Large coverage: diameter of 7 meters Iron bars

  42. A prototype in the making Resolution: ~60ps (6x10-11second) Signal propagation velocity: ~60ps/cm Spatial resolution: ~1cm 20x larger than the TOF modules Install in next RHIC data taking 1meterx20cm

  43. Conclusions (a colorful journey) • Perfect Liquid • Continue to explore its: • Flavor, color, sound, temperature • Viscosity, in-medium mass, critical point, correlation length • Multi-discipline: string, condensed matter, DIS, atomic, astrophysics • Detector and accelerator upgrades necessary (RHIC II) The Holy Grail is not in the finding. It is in the journey! Saul Zaentz, 1997

  44. BACKUP

  45. 作业题 I 你认为RHIC主要经费支出(~1.5亿/年)是什么? • 买黄金(Au+Au collisions,1010 ions per 8 hours) • 付电费 (15 megawatts) • 付员工工资(~400科学家,工程师,技术工) • 分给合作单位 (~100 institutions, ~20 countries) • 发展新项目 (Rearch&Development) • 捐献给慈善机构

  46. 作业题 II 1）一只蚊子以其正常飞行速度撞到静止的玻璃，所损失的动能， 和RHIC 200 GeV p+p collision一个事例的总能量相比? 2）RHIC 200 GeV Au+Au collision 能量密度是水密度的几倍？ 3) QCD 相变温度是太阳表面温度的几倍？ 4) RHIC, LHC 能产生黑洞吗？

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