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News from the EIC

News from the EIC. Thanks to everybody to let me use slides, plots, ……. QCD and confinement. Asymptotic Freedom. Confinement. Small Distance High Energy. Large Distance Low Energy. Strong QCD. Perturbative QCD. High Energy Scattering. Spectroscopy. Gluonic Degrees of Freedom Missing

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News from the EIC

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  1. News from the EIC Thanks to everybody to let me use slides, plots, …….. RHIC/AGS User Meeting, June 2009

  2. QCD and confinement Asymptotic Freedom Confinement Small Distance High Energy Large Distance Low Energy Strong QCD Perturbative QCD High Energy Scattering Spectroscopy Gluonic Degrees of Freedom Missing  Search for mesons with exotic quantum numbers Gluon Jets Observed RHIC/AGS User Meeting, June 2009

  3. The major driver: “Nature of Glue” Despite the success of QCD our knowledge about glue is limited - we know it plays a dominant role: DIS ⇒ only 1/2 of a proton's momentum is carried by the quarks Completely dominates the structure of matter at low-x Quenched QCD explains mass spectrum to ± 10% Dominates structure of QCD vacuum (⇒ mass?) Glue determines essential features of strong interactions Nature of Glue RHIC/AGS User Meeting, June 2009

  4. What is the nature of glue at high density? How do strong fields appear in hadronic or nuclear wave functions at high energies? Do gluon densities saturate? What drives saturation, what’s the underlying dynamics What are the appropriate degrees of freedom (Pomerons?) Does the Color Glass Condensate describe matter at low-x? Questions to Address with the EIC • Universality of gluon dynamics & energy dependence • Is there a “fixed” point where all hadronic matter have a component of their wave function with the same behavior • Could a better knowledge of glue help solve the longstanding problem of confinement in QCD? • What’s the role in gluons in the nuclear structure? RHIC/AGS User Meeting, June 2009

  5. What to Measure and in What System? • Understanding the role of the glue in matter involves understanding its key properties which in turn define the required measurements: • What is the momentum distribution of the gluons in matter? • e+p and e+A • Exploration of saturation regime only possible in e+A • What is the space-time distributions of gluons in matter? • e+p and e+A • Unknown in e+A • How do fast probes interact with the gluonic medium? • Strength of e+A • Do strong gluon fields effect the role of color neutral excitations (Pomerons)? • e+p and e+A • Unknown in e+A RHIC/AGS User Meeting, June 2009

  6. Deep Inelastic Scattering Photon: Quark: FF DF Hadron: Important kinematic variables: q cross section: Spin 1 RHIC/AGS User Meeting, June 2009

  7. Scaling violation:dF2 /dlnQ2and linear DGLAP Evolution ⇒G(x,Q2) Measure Glue through DIS RHIC/AGS User Meeting, June 2009

  8. Linear DGLAP evolution scheme Weird behavior of xG from HERA at small x and Q2 G(x,Q2) < Qsea(x,Q2) ? Unexpectedly large diffractive cross-section built in high energy “catastrophe” xG rapid rise violates unitary bound Linear BFKL Evolution Density along with σ grows as a power of energy: N ~ sΔ Can densities & cross-section rise forever? Black disk limit: σtotal≤ 2 π R2 Issues with our Current Understanding RHIC/AGS User Meeting, June 2009

  9. Universality & Geometric Scaling • Crucial consequence of non-linearevolution towards saturation: • Physics invariantalong trajectories parallel to saturation regime (lines of constant gluon occupancy) • Scale with Q2/Q2s(x) instead of x and Q2 separately • ⇐Geometric Scaling • Consequence of saturation which manifests itself up tokT > Qs x < 0.01 RHIC/AGS User Meeting, June 2009

  10. Assume: L = 3.8 1033 cm-2 s-1 T = 10 weeks duty cycle: 50% L ~ 1/A (approx) ∫Ldt = 11 fb-1 FL: measure glue directly ⇒G(x,Q2) with great precision FL ~ αs G(x,Q2) requires √s scan Q2/xs = y Plot contains: ∫Ldt = 4/A fb-1(10+100) GeV = 4/A fb-1(10+50) GeV = 2/A fb-1(5+50) GeV statistical errors only Can start at 2+100 GeV! RHIC/AGS User Meeting, June 2009

  11. Parton Propagation and Fragmentation EIC HERMES π • nDIS: • Suppression of high-pT hadrons analogous but weaker than at RHIC • EIC: Clean measurement in ‘cold’ nuclear matter • Energy transfer in lab rest frame • EIC: 10 < ν < 1600 GeV HERMES: 2-25 GeV • EIC: can measure heavy flavor energy loss • Work in Progress: • Simulation with PYTHIA 6.4.19 • 10 weeks of beam at eRHIC • 10+100 GeV • Large reach in Q2 and pT • small ν - hadronization inside A • large ν - precision tests of QCD • parton energy loss • DGLAP evolution and showers Nuclear Modification Measure: RHIC/AGS User Meeting, June 2009

  12. How do the partons contribute DG SqLq Lg SqDq SqDq Lg SqLq dq DG dq Is the proton spinning like this? N. Bohr W. Pauli gluon spin “Helicity sum rule” Where do we stand solving the “spin puzzle” ? angular momentum total u+d+s quark spin RHIC/AGS User Meeting, June 2009

  13. Polarized Quark Distributions EIC: 10GeV@250GeV at 9 fb-1 0.8 0. 0.2 -0.8 DSSV: arXiv:0904.3821 RHIC/AGS User Meeting, June 2009 X

  14. How to measure DS and DG • DG: Indirect from scaling violation g1@EIC Integrated Lumi: 5fb-1 RHIC/AGS User Meeting, June 2009

  15. The Gluon Polarization x small-x 0.001<x<0.05 RHIC range 0.05·x· 0.2 large-x x>0.2 Dg(x) very small at medium x best fit has a node at x~0.1 huge uncertainties at small x Need to enlarge x-range Dg(x) small !? g*p D0 + X RHIC/AGS User Meeting, June 2009

  16. Beyond form factors and quark distributions X. Ji, D. Mueller, A. Radyushkin (1994-1997) Proton form factors, transversecharge & current densities Structure functions, quark longitudinal momentum & helicity distributions Generalized Parton Distributions Correlated quark momentum and helicity distributions in transverse space - GPDs RHIC/AGS User Meeting, June 2009

  17. How to access GPDs? quantum number of final state selects different GPDs: • theoretically very clean • DVCS(g):H, E, H, E • VM(r, w, f):H E • info on quark flavors • PS mesons(p, h):H E ~ ~ ~ ~ RHIC/AGS User Meeting, June 2009

  18. Deeply Virtual Compton Scattering p + D DVCS Bethe-Heitler (BH) isolate BH-DVCS interference term non-zero azimuthal asymmetries most clean channel for interpretation in terms of GPDs HERMES / JLAB kinematics: BH >> DVCS two experimentally undistinguishable processes: can measure DVCS – cross section and I RHIC/AGS User Meeting, June 2009

  19. Results from Theory Lattice: K. Kumericki & D. Mueller arXiv: 0904.0458 contribution to nucleon spin CLAS BSA Hermes BCA First hints for a small JqLq Hall A Hall A mp2 GeV2 different GPD parametrisations LHPC Collab. hep-lat/0705.4295 t=0 t=-0.3 RHIC/AGS User Meeting, June 2009

  20. DVCS @ EIC • Need wide x and Q2 range to extract GPDs • Need sufficient luminosity to bin in multi-dimensions RHIC/AGS User Meeting, June 2009

  21. ERL-based eRHIC Design • 10 GeV electron design energy. • Possible upgrade to 20 GeV by • doubling main linac length. • 5 recirculation passes ( 4 of them in the RHIC tunnel) • Multiple electron-hadron interaction points (IPs) and detectors; • Full polarization transparency at all energies for the electron beam; • Ability to take full advantage of transverse cooling of the hadron beams; • Possible options to include polarized positrons: compact storage ring; compton backscattered; undulator-based. Though at lower luminosity. e-ion detector Possible locations for additional e-ion detectors eRHIC PHENIX Main ERL (1.9 GeV) STAR Beam dump Low energy recirculation pass Four recirculation passes Electron source RHIC/AGS User Meeting, June 2009

  22. ERL-based eRHIC Parameters: e-p mode RHIC/AGS User Meeting, June 2009

  23. ERL-based eRHIC Parameters: e-Au mode RHIC/AGS User Meeting, June 2009

  24. Luminosity and cooling no cooling Pre-cooling of the protons at the injection energy (22 GeV) is required to achieve proton beam-beam limit (xp=0.015) and maximize the luminosity. It can be done by electron cooling (in ~1h). To reduce the electron current requirements it would be great to have the effective transverse cooling at the storage energy (250 GeV) which can effectively counteract IBS and maintain the emittance well below 6p mm*mrad. Recent revival of the Coherent Electron Cooling idea (V.N.Litvinenko, Ya.S.Derbenev) brings the possibility of the effective longitudinal and transverse cooling for high energy protons. Proof of principle test of CEC has been suggested at RHIC. RHIC/AGS User Meeting, June 2009

  25. Geometrical constraints: If it is possible use the existing interaction region at RHIC 2 o’clock and wider tunnel to place the superconducting linac inside it. Minimize civil construction cost and use for eRHIC already built and installed linac. Medium Energy EIC in RHIC: race track concept RHIC/AGS User Meeting, June 2009

  26. IR2 Hall: Detector and Injector System 95 MeV ERL Soft bend 0.05T, 1m Beam Dump 250 (500) kW Bunching section Wien Spin rotator Polarized gun 200 keV DC with combiner cavity 5 (10) MeV Linac RHIC/AGS User Meeting, June 2009

  27. Requirements from Physics • ep-physics • the detector needs to cover inclusive  semi-inclusive  exclusive reactions • large acceptance absolutely crucial • particle identification (p,K,p,n) over wide momentum range • excellent vertex resolution (charm) • particle detection for very low scattering angle • uncertainty for e/p polarization measurements • luminosity measurement uncertainty • eA-physics • requirements very similar to ep • most challenging get information on recoiling heavy ion from exclusive and diffractive reactions. RHIC/AGS User Meeting, June 2009

  28. First ideas for a detector concept Solenoid (4T) Dipol 3Tm Dipol 3Tm / TRD RHIC/AGS User Meeting, June 2009

  29. Accelerator and detector integration and SR protection Solenoid (4T) Dipole ~3Tm J.Beebe-Wang, C.Montag, B.Parker, D.Trbojevic Dipole ~3Tm To provide effective SR protection: -soft bend (~0.05T) is used for final bending of electron beam -combination of vertical and horizontal bends RHIC/AGS User Meeting, June 2009

  30. ELIC Figure-8 Collider Ring Footprint WM City of NN State City of NN MEIC Footprint (~600m) SURA ELIC Footprint (~1800m) CEBAF Medium Energy IP Snake Insertion 60° Low Energy IP • Ring design is optimized with • Synchrotron radiation power of e-beam • prefers large ring (arc) length • Space charge effect of i-beam • prefers small ring circumference • Multi IPs require long straight sections • Straight sections also hold required components (e-cooling, injection and ejections, etc.) RHIC/AGS User Meeting, June 2009

  31. EIC@JLab at Low to Medium Energy polarimetry • Three compact rings: • 3 to 11 GeV electron • Up to 12 GeV/c proton (worm) • Up to 60 GeV/c proton (cold) RHIC/AGS User Meeting, June 2009

  32. EIC@JLab Parameters at Low-to-Medium Energy RHIC/AGS User Meeting, June 2009

  33. ELIC at High Energy & Staging p Ion Sources SRF Linac prebooster p p MEIC collider ring ELIC collider ring e e e injector 12 GeV CEBAF Interaction Point electron ring Ion ring Vertical crossing RHIC/AGS User Meeting, June 2009

  34. EIC@JLab Parameters: High Energy Major design change: symmetric IR  asymmetric IR RHIC/AGS User Meeting, June 2009

  35. Summary and A wealth of science @ EIC • A lot of work a head of us • need to finalize a compelling physics case for medium and high energy EIC • need to come from a detector sketch to a detector design • simulate golden physics channels in a detector frame-work • start machine, detector and “physics” R&D • have several LDRDs submitted • everybody who wants to join is more than welcome; regular TF meetings Thursday @ 2pm at BNL • 2 proposals in Europe: • low energy: ENC @ FAIR (e: 3.5 GeV, p: 15GeV) • high energy: LHeC @ CERN (e: 70 – 140GeV, p/A: LHC) RHIC/AGS User Meeting, June 2009

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