1. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute1 nFirst physics at RHIC with 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au+Au collisions: THE LITTLE BIG BANG nEcm=  s  40 TeV n4000-5000 charged particles produced per collision nTransparency or Stopping ? nTowards nuclear ’stuff’ with matter-antimatter balance BRAHMS Y2000 + Y2001 @ RHIC:  s nn =130 GeV, and  s nn =200 GeV

2. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute2 Quark Gluon Plasma Hot and dense matter QGP HG Freeze out Hadron gas Mixed phase QGP Pre-equil. quark 2.10 12 K

3. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute3 The particle Zoo Basic ’animals’

4. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute4 Quark ’Lego’. Hadrons Weak decay Hadronic interaction Strange

5. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute5 Confinement, jets, asymptotic freedom, color ropes etc… The quarkonium potential 2m q c 2 Hadron Meson

6. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute6 URQMD simulation of Au+Au at  s nn =200 GeV nRapidity y = ½ ln (E+pz / E- pz) = ½ ln(1+  cos  / 1-  cos  ) y(lab) = y + y(cm) nPseudorapidity  = ln (cot [  /2]) nTransverse momentum p t = p sin 

7. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute7 Central Au+AU collision event in STAR

8. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute8 RHIC physics August 2000 & August 2001 2:00 o’clock 4:00 o’clock 6:00 o’clock 8:00 o’clock 10:00 o’clock STAR PHENIX RHIC AGS LINAC BOOSTER TANDEMS 9 GeV/u Q = +79 1 MeV/u Q = +32 HEP/NP  g-2 U-line BAF (NASA) BRAHMS: L peak = 3.3  10 25 cm -2 s -1 L ave = 1.7  10 25 cm -2 s -1 Rcoll= 350 Hz PHOBOS 6  b -1 2 wks August 2000 and 2001

9. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute9 BRAHMS in the 2’ hall … in 1998

10. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute10 Forward & Midrapidity spectrometers in 2001 FS: 2 TPC, 2 TOF, C1-threshold, 3 Drift Ch. Mod., RICH, 4 Dipoles 2.5 - 30 deg.  = 1.5 - 4 MRS: 2 TPC, 1 Dipole, 1TOF 30 - 90 deg.  = 0 - 1.5

11. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute11 I.G. Bearden 7, D. Beavis 1, C. Besliu 10, Y. Blyakhman 6, J. Bondorf 7, J.Brzychczyk 4, B. Budick 6, H. Bøggild 7, C. Chasman 1, C. H. Christensen 7, P. Christiansen 7, J.Cibor 4, R.Debbe 1, J. J. Gaardhøje 7, M. Germinario 7, K. Grotowski 4, K. Hagel 8, O. Hansen 7, H. Heiselberg 7, A. Holm 7, A.K. Holme 12, H. Ito 11, E. Jacobsen 7, A. Jipa 10, J. I. Jordre 10, F. Jundt 2, C. E. Jørgensen 7, T. Keutgen 9, E. J. Kim 5, T. Kozik 3, T.M.Larsen 12, J. H. Lee 1, Y. K.Lee 5, G. Løvhøjden 2, Z. Majka 3, A. Makeev 8, B. McBreen 1, M. Murray 8, J. Natowitz 8, B.S.Nielsen 7, K. Olchanski 1, D. Ouerdane 7, R.Planeta 4, F. Rami 2, D. Roehrich 9, B. H. Samset 12, S. J. Sanders 11, D. Sandberg 7,I. S. Sgura 10, R.A.Sheetz 1, Z.Sosin 3, P. Staszel 7, T.S. Tveter 12, F.Videbæk 1, R. Wada 8 and A.Wieloch 3. 1 Brookhaven National Laboratory, USA 2 IReS and Université Louis Pasteur, Strasbourg, France 3 Jagiellonian University, Cracow, Poland 4 Institute of Nuclear Physics, Cracow, Poland 5 Johns Hopkins University, Baltimore, USA 6 New York University, USA 7 Niels Bohr Institute, Blegdamsvej 17, University of Copenhagen, Denmark 8 Texas A&M University, College Station. USA 9 University of Bergen, Norway 10 University of Bucharest, Romania 11 University of Kansas, Lawrence,USA 12 University of Oslo Norway BRAHMS Intl. collaboration

12. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute12 First BRAHMS collision at 100 AGeV+100AGeV T1 MTPC1 T2 MTPC2 MRS: 90 deg 6.5 msr FS: 6 deg 0.8 msr

13. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute13 BRAHMS acceptance Y2000 & Y2001

14. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute14 Centrality determination Vertex distribution 1m

15. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute15 TPC tracks, Vertex reconstruction, Charged particle track density MTPC1 z y

16. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute16 dN ch /d  @  s nn = 130 GeV SiMA, TMA, BB, TPC nN=  dE / nP(0)/P(n  1) nBackground corr.due to secondaries (37-50%) nConsistency between 4 independent detector systems n65 AGeV+ 65 AGeV: n  N(ch)d  = 3860±300 nCentral 0-5% dN(ch)/d  (  =0) =550 nFWHM of distribution  = 7.6  0.7 0-5% 10-20% 20-30% 30-40% 40-50% 5-10% 600 BRAHMS Phys. Lett. B 523 (2001) 227; nucl-ex 0108015

17. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute17 Background… A slight complication

18. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute18 RHIC: 200 AGeV Will this happen?

19. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute19 Whirlpool Galaxy. M51, Hubble space telescope

20. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute20 Pseudorapidity densities @ 200 AGeV n5630 charged particles produced for 0- 5% central n14% increase over 130GeV n50% increase over p +  p (UA5) => significant medium effects Bjorken energy density  BJ = (1/  R 2  0 ) dE t /d   5 GeV/fm 3 dE t =dN cf:  QGP critical  1 GeV/fm 3 Brahms 200 pppp

21. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute21 Hard and Soft vs. High Density QCD @ 200 AGeV nKharzeev and Levin (nucl- th/0108006) nHIGH DENSITY QCD MODEL nSoft-Hard: dN/d  =(1-X) n pp /2 + X n pp =1049, =339, npp=2.43 =>dN/d  =668 (with X=0.9) nHigh Density QCD-saturation: dN/dy = f( Npart, Q s 2,,  QCD,  s,y) with =0.3 from HERA data => dN/d  =620 (using dN/d  =549 at  s=130GeV) BRAHMS Submitted to PRL dec. 2001 Nucl-ex. 00112001  =4.5  =3.0  =0 Gluon saturation ?

22. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute22 Saturation of excitations in fragmentation region Shift data to beam frame of reference BRAHMS subm. to PRL- n-ex. 00112001

23. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute23 Hadron identification MRS (90 - 40 deg). TOF m 2 =p 2 ( t 2 / L 2 -1)

24. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute24 Hadron Identification FS (4-20deg @200AGeV) C1,H1,T2 ++ p K+ 4 deg

25. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute25 C1 Threshold Cherenkov PID Cos  =1/n  =>  th =1/n

26. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute26 Ring Imaging Cherenkov for high momentum PID   R 

27. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute27 Antiparticle/particle ratios @ 200AgeV ’+’  ’-’ p - /p = p - (pair) / [p+p(pair)] K - /K + = K - (pair) / [K + (pair)+K + (ap)] (p+p  p+  +K +)  +  - pair prod (& ch. exch). Midrapidity: near matter-antimatter balance ++ BRAHMS Preliminary

28. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute28 How consistent are the models @  s nn = 130GeV?

29. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute29 Summary: First Au+Au  s nn =130 & 200 GeV nHighest particle multiplicity in nuclear collisions ( 4600 ch. part) ever seen nLarge(st) energy density > 5  crit nHigh reaction transparency nDecoupling of central and ’fragmentation’ regions nPartonic (color) description appears necessary nCentral region dominated by matter-antimatter balance:  Qualitatively new physics regime To come: Strangeness, fluctuations, net baryon density, jet quenching, …. 2006: ALICE @ LHC -CERN  s nn =6000 GeV, Pb+Pb

30. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute30 Extra’s

31. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute31 ALICE at LHC point 2 CERN

32. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute32 ALICE TPC

33. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute33 Pbar/p ratio systematics

34. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute34 Fluctuations in particle production Fluctuations in multiplicity  = ( - 2 ) / Participant model: =  =  (int) + N.  (Np)

35. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute35 Intrinsic fluctuations in particle production  =  (int)+  (b)+  (mom)+  (second)+  (vertex)

36. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute36 Multiplicity 200 AGeV / 130 AGeV

37. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute37 Electromagnetic nuclear dissociation LO+NLO Mutual EM Mutual Electromagnetic dissociation (Spectrum of virtual photons) * (absorption cross section) = WW Multiphonon GDR excitation,  abs EM vs Nuclear coll. => neutron (L*R) coincidences RELDIS. Pshenichnov, JPB, IM, et al. EM dissociation selected by ZDC coincidences and TMA Veto in BRAHMS n n n 2n 1n LO NLO

38. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute38 Neutral Energy correlations (ZDC) C2(E L,E R )=P(E L,E R )/(P(E L )*P(E R ))

39. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute39 N(p-bar)/N(p) systematics vs CM energy

40. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute40 Strangeness K-/K+ vs y @  s nn = 130GeV BRAHMS Preliminary CERN-SPS

41. Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute41 Bjorken limit reached for Au+Au  s nn = 130GeV? ISR R803  s=23  s=63 BRAHMS PRL87(2001)112305