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Contents Introduction The Experiments (PHENIX detector) Physics Highlights Conclusion

RHIC Spin Project opening a new era of hadron physics Hideto En’yo RIKEN / RIKEN-BNL Research Center. Contents Introduction The Experiments (PHENIX detector) Physics Highlights Conclusion. 3.83 km circumference Two independent rings 120 bunches/ring 106 ns bunch crossing

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Contents Introduction The Experiments (PHENIX detector) Physics Highlights Conclusion

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  1. RHIC Spin Projectopening a new era of hadron physicsHideto En’yo RIKEN / RIKEN-BNL Research Center Contents • Introduction • The Experiments (PHENIX detector) • Physics Highlights • Conclusion Hideto En'yo RIKEN/RBRC

  2. 3.83 km circumference • Two independent rings • 120 bunches/ring • 106 ns bunch crossing • Can collide ~any nuclei on ~any other nuclei • Top Energy: 500 GeV for p-p 200 GeV for Au-Au • Luminosity • Au-Au: 2 x 1026 cm-2 s-1 • p-p : 2 x 1032 cm-2 s-1(polarized) ISABELL (abandoned in 1983) to RHIC (started in 2000) The First Heavy Ion Collider & The first Polarized Collider

  3. Year2000 to Year2001 First Collision of Gold beams at 130 GeV/A 10% of Designed Luminosity achieved Successful Physics Run Successful Spin Commissioning! • First Collision of Gold beams at 200GeV/A !!! • Currently running with Au+Au Beam • with ~design luminosity. • First Muon Data from PHENIX • First Polarized Proton Collision will take place in November – December, 2001! Hideto En'yo RIKEN/RBRC

  4. RHIC pC Polarimeters BRAHMS & PP2PP PHOBOS Absolute Polarimeter (H jet) RHIC PHENIX STAR Siberian Snakes Spin Rotators 2  1011 Pol. Protons / Bunch e = 20 p mm mrad Partial Siberian Snake LINAC BOOSTER Pol. Proton Source 500 mA, 300 ms AGS AGS Internal Polarimeter Rf Dipoles 200 MeV Polarimeter RHIC Polarized Collider KEK Illustrated by Thomas Roser Hideto En'yo RIKEN/RBRC

  5. Milestones Pre- RHIC History • Naive quark model S = 1 = Du+Dd+Ds • 1973 Ellis-Jaffe sum rule Ds =0 → g1pdx,g1ndx predicted • 1974 Sehgal’s spin crisis Ds =0 →S = 0.58  1 • 1989 -99 EMC spin crisis S = 0.2-0.3 , Ds = -0.1 ? • Looking for the OTHER spin Carrier • 1/2=(1/2)DS+DG+Lq+Lg • 1989 RHIC project started • 1990 Polarized Collider Workshop at Penn State • 1992 STAR and then PHENIX, approved for RHIC • 1993 RHIC-Spin proposal(Accelerator,STAR,PHENIX) • 1995 RIKEN-BNL MoU[Spin construction started] • 1997 RIKEN-BNL Research Centerestablished (T.D.Lee) • 2000 The first HI collisions & polarized proton acceleration • 2001 The first polarized proton collisions History to Wedding of HI & SPIN at RHIC Hideto En'yo RIKEN/RBRC

  6. Spin Structure of Nucleon Parton Distribution Function Unpolarized Distribution Helicity Distribution Transversity Distribution D.I.S. Quark Distribution Gluon Distribution RHIC Hideto En'yo RIKEN/RBRC

  7. Impact of RHIC Spin on Dg Global QCD Analysis With RHIC DATA (1year) AAC Preliminary AAC Preliminary M. Hirai, H.Kobayashi, M. Miyama et al. Hideto En'yo RIKEN/RBRC

  8. Spin Physics at RHIC RHIC = polarized parton collider • Spin Structure of Nucleon • 1/2=(1/2)DS+DG+Lq+Lg • DG: gluon polarization • Dq: Anti-quark polarization • New Structures • h1: transversity • NEW TOOL to study hadronic processes • W,Z @500GeV • flavor sensitive studies on the structure functions • cc/bb • Production mechanism • Spin in the fragmentation • Parity,CP violating interaction? • Test of pQCD • Use asymmetries sensitive ONLY to the higher orders (AN at high PT etc.) ?QCD triumph? or ?beyond ? Hideto En'yo RIKEN/RBRC

  9. Asymmetries Measurements • ALL:Double Longitudinal Spin Asymmetry • Useful in extracting quark/gluon helicity distributions AN:Twist-3 or T ATT: Transversity AL:Parity Violation Hideto En'yo RIKEN/RBRC

  10. Remarks in the Asymmetry Measurements Asymmetry Measurements Effect of Background Adata = Asignal [ 1/(1+e) ]+ Aback [e/(1+e) ] e=Nback/Nsignal Keys • Luminocity (STATISTIC !) • Polarization (>70% expected at RHIC) • Large Partonic Asymmetry (Choose good channel) • LowBackground (Clean signal and/or clean analysis) • LowBackgroundAsymmetry (better measured within the same experiment) 　ｇｇ→QQ Dilution Fake Asymmetry Hideto En'yo RIKEN/RBRC

  11. STAR Acceptance PHENIX STAR

  12. Central Arms Coverage (E&W) -0.35< y < 0.35 30o <|f |< 120o DM(J/y )= 20MeV DM(g) =160MeV PHENIX DETECTOR Muon Arms Coverage (N&S) -1.2< |y| <2.3 -p < f < p DM(J/y )=105MeV DM(g) =180MeV 3 station CSC 5 layer MuID (10X0) p(m)>3GeV/c WestArm Globals MVD/BB/ZDC East Arm South muon Arm North muon Arm Hideto En'yo RIKEN/RBRC

  13. EM-calorimeter (gift from HI physics) PHENIX Segmentation p0 opening angle 30/25/20/15/10 GeV/c Pt ofp0 • Fine segmentation Df<0.01 • finest in the collider history g/p0 separation up to 25GeV • linearity <2% up to 80GeV • Resolution 1.9%  8.2%/E Hideto En'yo RIKEN/RBRC

  14. MuonArms • 3 stations W 5 layer Muon Identifier Double Muon Arm solution is Major Upgrade in PHENIX for SPIN Works as Up-Down counters for mn-decay of polarized W Hideto En'yo RIKEN/RBRC

  15. PHENIX Spin Physics Probes Y. Goto (RBRC) A. Vazilevsky(RBRC) N. Saito (RIKEN/RBRC) H. Torii(Kyoto/RIKEN-JRA) • Measurements with Central Arms • Direct photon - inclusive p0 • J/ye+e- - W±e±n • inclusive high Pt e± • Measurements with Muon Arms • inclusive high Pt m± - J/ym+m- • Z/g* m+m-- W±m±n • Measurements with both Arms • cc/bbm±e +X (unlike sign pair) • g/leptons penetrating Quark Matter also probe pQCD insite • Polarized proton Delivered from RHIC • 1-Year Ldt =320/pb at 200GeV 800/pb at 500GeV, (10weeks/y) • High polarization ~70% expected ( KEK pol. source ) • Y2001: 6 weeks L~1/10 Pol~50% N. Saito (RIKEN/RBRC) H. D.Sato(Kyoto/RIKEN-JRA) N. Hayashi(RIKEN) A. Taketani(RIKEN) K. Kurita (RIKEN) Hideto En'yo RIKEN/RBRC

  16. Jet Production • Mixture of gg/gq/qq scatterings • Very sensitive to gluon polarization Hideto En'yo RIKEN/RBRC

  17. Y. Goto N.Saito Measurements of DG (gg,gq,qq→p0X) 10 times more yield than g fromGluon Compton Process • convolution of all the partonic asymmetry • Model dependent but DG sensitive from g+q, g+g scatterings • Accessible with 1/10 Luminosity. • Good start for 1st-year physics • Immediate answer if ⊿ｇ is large One-Month statistic with full luminosity Hideto En'yo RIKEN/RBRC

  18. A. Vazilevsky Y. Goto Measurements of DG (gq→gX) The primary goal of the RHIC spin project • Clean elementary process • Background • qq annihilation (~10%, not rejectable) • Bremsstrahlung from jet frangments • Hadronic Decays • Yield Phenix 1-year sensitivity 320 pb-1 800 pb-1 120K events 1,160K events Hideto En'yo RIKEN/RBRC

  19. Y. Goto Decay background ~20% Gluon Polarization Sensitivity • x・DG(x) derived from prompt g measurements • only statistical error for; • sqrt(s)=200GeV 320pb-1 • sqrt(s)=500GeV 800pb-1 • crude assumptions as; • xg=xT=2pT/sqrt(s) • cos(q*)=0 • Convolution over xBJ space and NLO consideration are required. • global structure can be seen immediately Hideto En'yo RIKEN/RBRC

  20. H.D.Sato Kyoto /JSPS Measurements of DG ｇｇ→QQ → em • em coincidence enhance the leptons from heavy quarks • 320/pb provides 120k bb,100k cc,100k hadronic decays • Like sign pair (also includes signal from bb) gives fine estimation for the background effects total cc bb KDecays KDecays Hideto En'yo RIKEN/RBRC

  21. H.D.Sato Kyoto /JSPS Measurements of DGｇｇ→QQ → (J/y) Color octet model ALL prediction • Gluon fusion is the major production channel (agreed) • Details are questionable over 20 years. • Color evaporation • Color octet • Color singlet • Decay from cc J/ （color singlet model） 320pb-1 pT()>2GeV/c NJ/ (pT>2GeV)~120k events →ALLJ/(stat.)~ 0.006 →Error from Back ground ~ 0.001 Precise ALL measurements first to verify the production models bottom /K GeV/C2 Hideto En'yo RIKEN/RBRC

  22. Kinematical Coverage: (x,Q2) • @200GeV • Similarly to DIS region • @500GeV • Coverage Enlarged! • Advantageous in Global QCD Analysis! 200GeV γ 200GeV eμ 200GeV e(cc) Hideto En'yo RIKEN/RBRC

  23. N.Saito Weak Boson Detection at PHENIX • W production is • Flavor sensitive • helicity fixed (V-A) Kinematics (realized by N.Saito ) • power of the polarized collider with Muon Endcaps Yield in 1-RHIC year at 500GeV Hideto En'yo RIKEN/RBRC

  24. N.Saito Measurements of Dq, Dq at PHENIX Parity violating single Asymmetry unpolarized distribution  polarized distribution • d small at high x Du/u (Dd/d for W-) flavor selected valence quark polarization • Dd/d (Du/u for W-) determination Major background is Z decay (20%) systematic error will be minimized (~1%) with ALZ (~20%)and s(Z) measurements Hideto En'yo RIKEN/RBRC

  25. Flavor Structure of Nucleon • Recent FNAL Data shows 50% difference in p+p/p+d (D.Y.) • No reason to assume d = u in nucleon • Dd Du is natural • RHIC • W+/W- Yield comparison • p+p then p+He3 ? J.C.Peng,G.T.Garvey du d=u FNAL-E866 results PRL 80 (1998) 3715 PHENIX Wm PHENIX Wm PHENIX We Hideto En'yo RIKEN/RBRC

  26. Searches for New Physics • Anomalous Parity Violation in Jet Production • Contact Interaction (Scale L) • CDF L>1.8 TeV • D0 L>2.4 TeV • RHIC Spin Reach L~3.3 TeV • New Gauge Boson Z’ Hideto En'yo RIKEN/RBRC

  27. pC CNI Polarimeterproton Carbon Elastic Scattering up Si #3 Si #1 right left Si #2 Si #4 down • Designed Basing on Successful AGS-E950 Measurement • Installed in Blue Ring • 4 detectors: 45o,135o,225o,315o J. Tojo et al. Hideto En'yo RIKEN/RBRC

  28. pC CNI Polarimeter Testin AGS E950 & Kyoto Tandem Gg=46.5 Injection energy Snake OFF Vertical polarization Gg=46.5 Injection energy Snake ON Horizontal polarization Gg=48 Acceleration with Snake ON Horizontal polarization Gg=48 Acceleration with Snake OFF Polarization lost Polarization with Snake magnet ON/OFF up Si #3 Si #1 right left Si #2 Si #4 down

  29. Conclusions • RHIC Spin program is very unique. • Y2000 Polarized proton commissioning was very successful. • Y2001, The first measurements of helicity asymmetry will SOON be performed @200GeV. Sizable DG generates surprises in the High pTp0 , High pTm , J/y data. • Y2002+, Statistics will be much improved @200GeV, ensuring the determination of DG in direct g and e-m coincidence data. “Spin Crisis” will hopefully be solved by them. • Y200?, Weak Bosons will be produced at RHIC, the NEW “flavor sensitive” tool for the anti-quark/quark polarization and unpolarized structure function of anti-quark measurements. • And beyond… Hideto En'yo RIKEN/RBRC

  30. L and E Upgrades • Luminosity Upgrades: 25 Times • 8 Times by Ion Source • 3 Times by increasing number of bunches: • 120 bunches  360 bunches • 106 nsec bunch spacing to 35.3 nsec • Energy Upgrades: 500 GeV  650 GeV • RHIC Dipoles: 30% Margin • RHIC DX Magnets: 10% Margin • With DX Magnet Upgrade, 650 GeV Collision is possible Hideto En'yo RIKEN/RBRC

  31. Background reduction • segmenttation • p0gisolate+gmerged • prompt g +decayg • mass reconstruction p0 • isolation cut • R=0.4, E-fraction=5% Measurements of DG (gq→gX) Hideto En'yo RIKEN/RBRC

  32. H.D.Sato Kyoto /JRA Measurements of DGｇｇQQ (μsingle) • Large statistics but with significant background s bb is 0.7mb in PYTHIA < a few mb expected • Source of background • Decays before Central Magnet • Punch-through hadrons • g+g, g+q dominant • ALLfake ~ ALLsignal • Background evaluation • 5 layer MuID for punch through estimation • Decay muon control with vertex position Asymmetry may well be sizable Good exercise for the 1st year run 320pb-1 → c→ b→ Hideto En'yo RIKEN/RBRC

  33. Drell-Yan in PHENIX Dq measurements ALL h1 measurements ATT Statistics are not great at high mass (>10GeV) where listed amplitude will be sizable. (not well studied yet) un-polarized structure function is not well determined ( revealed by the FNAL data) p+He3 might be the way to go @200GeV x1 0.1-0.5 vs x20.001-0.01 FNAL E886 Hideto En'yo RIKEN/RBRC

  34. H.D.Sato Kyoto/RIKEN-JRA em coincidence in PHENIX x1 x2 Central Arm ｂ→e P x1P ｂ→ x2P ALLpp→bbＸ μ Muon Arm GS-A e ALL GS-B GS-C Me(GeV) Hideto En'yo RIKEN/RBRC

  35. World Competition of Dg/g(x) RHIC Spin is THE BEST MEASUREMENT among currently running experiments, even only with 1EXPT&1 CHANNEL. GS-C Hideto En'yo RIKEN/RBRC

  36. PHENIX DG sensitivity at a glance High Statistic Probes (1st year + later detail studies) Cleaner Probes (2nd Year and later)  Global approach to DG from many probes available Hideto En'yo RIKEN/RBRC

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