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The 12 GeV Upgrade of Jefferson Lab

The 12 GeV Upgrade of Jefferson Lab. Volker Burkert Jefferson Lab. Highlights of the 12 GeV Science Program. New and revolutionary access to the structure of the proton and neutron (GPDs, TMDs) Unlocking the secrets of QCD: confinement and space-time dynamics

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The 12 GeV Upgrade of Jefferson Lab

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  1. The 12 GeV Upgrade of Jefferson Lab Volker Burkert Jefferson Lab

  2. Highlights of the 12 GeV Science Program • New and revolutionary access to the structure of the proton and neutron (GPDs, TMDs) • Unlocking the secrets of QCD: confinement and space-time dynamics • Exploring the quark structure of nuclei • Precision tests of the Standard Model

  3. Add new hall CHL-2 Enhance equipment in existing halls JLab Upgrade to 12 GeV

  4. D C 9 GeV tagged polarized photons and a 4 hermetic detector Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles A B CLAS12 with new detectors and higher luminosity (1035 /cm2-s) High Resolution Spectrometer (HRS) Pair, and specialized large installation experiments New Capabilities in Halls A, B, & C, and a New Hall D

  5. New and revolutionary access to the structure of the proton and neutron

  6. CLAS12 • Lum > 1035cm-2s-1 • GPDs & TMDs • Nucleon Spin Structure • N* Form Factors • Baryon Spectroscopy • Hadron Formation Forward Detector Central Detector 2m

  7. Last 50 years Last 40 years Last 10 years ? Structure functions, quark longitudinal momentum & spin distributions Proton form factors, transverse charge & current densities Correlated quark momentum and helicity distributions in transverse space - GPDs Generalized Parton Distributions and 3D Quark Imaging

  8. hard vertices g x+x x-x –t – Fourier conjugate to transverse impact parameter t Basic Process – Handbag Mechanism Deeply Virtual Compton Scattering (DVCS) x x – longitudinal quark momentum fraction 2x – longitudinal momentum transfer GPDs depend on 3 variables, e.g. H(x, x, t). They probe the quark structure at the amplitude level. xB x = 2-xB What is the physical content of GPDs?

  9. Physical content of GPDs Nucleon matrix element of the Energy-Momentum Tensor contains three form factors: M2(t) : Mass distribution inside the nucleon J (t) : Angular momentum distribution d1(t) : Forces and pressure distribution GPDs are related to these form factors through moments

  10. H1, ZEUS Kinematics of deeply virtual exclusive processes H1, ZEUS 27 GeV 200 GeV JLab Upgrade JLab @ 12 GeV COMPASS W = 2 GeV Study of high xB domain requires high luminosity HERMES 0.7

  11. Ds 2s s+ - s- s+ + s- A = = The path towards the extraction of GPDs e p epg DsLU~sinf{F1H+..}df Kinematically suppressed Selected Kinematics Extract H(ξ,t)

  12. Projected precision in extraction of GPD Hat x = ξ Spatial Image Projected results

  13. 2D (Im(AB*)) AUT ~ - T Q2=5 GeV2 Exclusive r0production on transverse target Should be known from DVCS A ~ 2Hu + Hd r0 B ~ 2Eu + Ed Separate with ρ+ Eu, Ed measure the contributions of the quark orbital angular momentum to the nucleon spin. r0 B

  14. Target polarization dX(x,b ) uX(x,b ) T T q(x,b ) = d2t ∫ T e-i·t·bE(x,0,t) (2p)2 T flavor polarization Ed(x,t) Eu(x,t) Tomographic Images of the Proton M. Burkardt The guts of the proton? CAT scan slice of human abdomen

  15. Valence structure function flavor dependence Hall B 11 GeV with CLAS12

  16. Valence structure function spin dependence Proton Deuteron & He-3 W > 2; Q2 > 1

  17. Improvements in Δu, Δd, ΔG, Δs

  18. Important complement to RHIC Spin data

  19. Proton electric form factor

  20. At 12 GeV extend knowledge of magnetic structure of neutron to much shorter distances. Needed for constraints of GPDs at large t; related to moments of GPDs: F1(t)= ∫H(t,x,ξ)dx, F2(t)= ∫H(t,x,ξ)dx Neutron Magnetic Form Factor

  21. CLAS published CLAS preliminary CLAS12projected Projections for N* Transition Amplitudes @ 12 GeV Probe the transition from effective degrees of freedom, e.g. constituent quarks, to elementary quarks, with characteristic Q2 dependence.

  22. qqG 1GeV qq Hybrid mesons Flux Tube Model • Provides a framework to understand gluonic excitations. • Conventional mesons have the color flux tube in the ground state. When the flux tube is excited hybrid mesons emerge. For static quarks the excitation level above the ground state is ~1 GeV. • The excitation of the flux tube, when combined with the quarks, can lead to spin-parity quantum numbers that cannot be obtained in the quark model (JPC - exotics). • The decay of hybrid mesons leads to complex final states. JPC = 0+-, 1-+, 2+-

  23. LQCD supports the idea of flux tubes. Flux distribution between static quarks. Flux tubes lead to a linear confining potential.

  24. Exotic Hybrid Mesons Masses With 3 light quarks the conventional and hybrid mesons form flavor nonets for each JPC.

  25. Photons may be more suited to excite exotics • In the flux tube model, using photon beams, the production rate of hybrid mesons is not suppressed compared to conventional mesons. • N. Isgur, PRD (1999); A. Afanasev & A. Szczepaniak, PRD (2000); F. Close & J. Dudek (2004)

  26. GlueX – Exotic meson program at 12GeV To meet these goals GlueX will:

  27. CLAS12 Quark Propagation and Hadron Formation:QCD Confinement in Forming Systems • How long can a light quark remain deconfined? • The production time tp measures this • Deconfined quarks emit gluons • Measure tp via medium-stimulated gluon emission • How long does it take to form the color field of a hadron? • The formation time tfh measures this • Hadrons interact strongly with nuclear medium • Measure tfh via hadron attenuation in nuclei

  28. Expected data – Hadronic multiplicity ratio

  29. Color transparency in ρ electroproduction • ColorTransparency is a spectacular prediction of QCD: under the right conditions, nuclear matter will allow the transmission of hadrons with reduced attenuation • Totally unexpected in an hadronic picture of strongly interacting matter, but straightforward in quark gluon basis • Why ρ? Should be evident first in mesons

  30. The signature of CT is the rising of the nuclear transparency TA with increasing hardness of the reaction (Q) • Measurement at fixed coherence length needed for unambiguous interpretation

  31. CLAS preliminary Color transparency in ρ electroproduction 56Fe • Predicted results high-precision, will permit systematic studies CLAS12 projected

  32. Precision Tests of the Standard Model

  33. º e i 2 º C g g e i 2 C g g 2 i V A 1 i A V Electron-Quark Phenomenology V A A V C1u and C1d will be determined to high precision by APV and Qweak C2u and C2d are small and poorly known: can be accessed in PV DIS New physics such ascompositeness, new gauge bosons: Deviations in C2u and C2d might be fractionally large Proposed JLab upgrade experiment will improve knowledge of 2C2u-C2d by more than a factor of 20

  34. Parity Violating Electron DIS e- e- * Z* X N For an isoscalar target like 2H, one can write in good approximation: provided Q2 and W2 are high enough and x ~ 0.3 Must measure APV to fractional accuracy better than 1% • 11 GeV at high luminosity makes very high precision feasible • JLab is uniquely capable of providing beam of extraordinary stability • Control of systematics being developed at 6 GeV

  35. 2H Experiment at 11 GeV APV = 290 ppm E’: 6.8 GeV ± 10% lab = 12.5o 800 hours 60 cm LD2 target Ibeam = 90 µA xBj ~ 0.45 Q2 ~ 3.5 GeV2 W2 ~ 5.23 GeV2 1 MHz DIS rate, π/e ~ 1 HMS+SHMS (APV)=1.0 ppm (2C2u-C2d)=0.01 PDG: -0.08 ± 0.24 Theory: +0.0986

  36. Conclusions • The JLab Upgrade has well defined physics goals of fundamental importance for the future of hadron physics, addressing in new and revolutionary ways the quark and gluon structure of mesons, nucleons, and nuclei by • accessing generalized parton distributions • exploring the valence quark structure of nucleons • understanding quark confinement and hadronization processes • extending nucleon elastic and transition form factors to short distances • mapping the spectrum of gluonic excitations of mesons • searching for physics beyond the standard model • Design of accelerator and equipment upgrades are underway • Construction scheduled to begin in 2009 • Accelerator shutdown scheduled for 2012

  37. 2007 NSAC Long Range Plan (4 recommendations) Recommendation 1 We recommend the completion of the 12 GeV Upgrade at Jefferson Lab. - It will enable three-dimensional imaging of the nucleon, revealing hidden aspects of its internal dynamics. • It will complete our understanding of the transition between the hadronic and quark/gluon descriptions of nuclei. • It will test definitively the existence of exotic hadrons, long-predicted by QCD as arising from quark confinement. • It will provide low-energy probes of physics beyond the Standard Model complementing anticipated measurements at the highest accessible energy scales.

  38. We are here DOE Reviews DOE Generic Project Timeline

  39. A first search for exotic meson with photons Experiment planned to run in 2008. • Clarify evidence for exotic meson states, e.g. at 1600 MeV with high statistics. • Prepare for full study with GlueX. Events from previous CLAS experiment. a2 45 35 25 15 5 p2 a1 102 Events/ 20 MeV Gluonic Meson? p1(1600) 0.8 1.2 1.6 2.0 Expect 1-2 million 3-pion events, 3 orders more than any previously published meson photoproduction results, allowing a partial wave analysis.

  40. Physical content of GPDs J(t) M2(t) d1(t) repulsion attraction Angular momentum density Mass/energy density Pressure density In the Chiral Quark Soliton Model

  41. CLAS12-DVCS/BH Target Asymmetry e p epg E = 11 GeV Longitudinally polarized target ~ Ds~sinfIm{F1H+x(F1+F2)H...}df L = 2x1035 cm-2s-1 T = 1000 hrs DQ2 = 1GeV2 Dx = 0.05

  42. M = r0/r+ select H, E, for u/d quarks M = p, h select H, E Separating GPDs in Flavor & Spin DVMP DVCS hard vertices • DVCS depends on all 4 GPDs • Photons cannot separate u/d quark • contributions. Isolate longitudinal photons by decay angular distribution.

  43. stomach pancreas gall bladder liver right kidney CAT scan slice of human abdomen Can we do similar imaging in the microscopic world? Tools are being developed to add this new dimension to nuclear research.

  44. 3-D Scotty z 2-D Scotty z x y 1-D Scotty Deeply Virtual Exclusive Processes & GPDs Water Calcium probablity Carbon Deep Inelastic Scattering & Parton Distribution Functions. x x GPDs & PDFs

  45. y x=0.4 x=0.9 x=0.01 1 2 1.5 fm fm fm 0 0 0 -2 -1.5 -1 -2 0 fm 2 -1.5 0 fm 1.5 -1 fm 0 1 interference pattern Tomographic Images of the Proton II z X. Ji and F. Yuan, 2003 Charge density distributions for u-quarks 3D image obtained by rotation around the z-axis

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