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The JLab 12 GeV Upgrade Upgrade of accelerator and experimental equipment Highlights of the physics 12 GeV Highlights of spin dependent measurements.

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Presentation on theme: "The JLab 12 GeV Upgrade Upgrade of accelerator and experimental equipment Highlights of the physics 12 GeV Highlights of spin dependent measurements."— Presentation transcript:

1 The JLab 12 GeV Upgrade Upgrade of accelerator and experimental equipment Highlights of the physics 12 GeV Highlights of spin dependent 12 GeV Timelines and schedule Antje Bruell, JLab PacSpin 2007, Vancouver, Canada

2 Jefferson Lab Today 2000 member international user community engaged in exploring quark-gluon structure of matter A C Superconducting accelerator provides 100% duty factor beams of unprecedented quality, with energies up to 6 GeV CEBAFs innovative design allows delivery of beam with unique properties to three experimental halls simultaneously Each of the three halls offers complementary experimental capabilities and allows for large equipment installations to extend scientific reach B

3 A B C Jefferson Lab Today Two high-resolution 4 GeV spectrometers Large acceptance spectrometer electron/photon beams 7 GeV spectrometer, 1.8 GeV spectrometer, large installation experiments Hall A Hall B Hall C

4 6 GeV CEBAF CHL-2 Upgrade magnets and power supplies Enhanced capabilities in existing Halls Lower pass beam energies still available

5 Hall D – exploring origin of confinement by studying exotic mesons Hall B – understanding nucleon structure via generalized parton distributions Hall C – precision determination of valence quark properties in nucleons and nuclei Hall A – short range correlations, form factors, hyper-nuclear physics, future new experiments Experimental equipment for 12 GeV

6 Technical Performance Requirements Hall DHall BHall CHall A excellent hermeticity luminosity 10 x energy reachinstallation space polarized photonshermeticityprecision E GeV11 GeV beamline 10 8 photons/starget flexibility good momentum/angle resolutionexcellent momentum resolution high multiplicity reconstructionluminosity up to particle ID

7 Physics Experimental Equipment total project cost: $ 310 M

8 QCD and confinement Large Distance Low Energy Small Distance High Energy Perturbative QCD Strong QCD High Energy Scattering Gluon Jets Observed Spectroscopy Gluonic Degrees of Freedom Missing

9 Gluonic Excitations From G. Bali predicted by QCD crucial for understanding confinement quantum numbers of the excited gluonic fields couple to those of the quarks to produce mesons with exotic quantum numbers mass spectra calculated by lattice QCD possibility for experimental search Gluonic Excitations

10 Hybrid mesons Normal mesons 1 GeV mass difference Hybrid mesons and mass predictions J pc = 1 -+ q q q q Lattice GeV GeV GeV Lowest mass expected to be 1 (1+ ) at 1.9±0.2 GeV

11 GlueX / Hall D Detector Electron Beam from CEBAF Lead Glass Detector Solenoid Coherent Bremsstrahlung Photon Beam Tracking Target Cerenkov Counter Time of Flight Barrel Calorimeter Note that tagger is 80 m upstream of detector 12 GeV electrons collimated

12 Output: /- 3 MeV Output: 173 +/- 11 MeV Double-blind M. C. exercise Statistics shown here correspond to a few days of running. Mass Input: 1600 MeV Width Input: 170 MeV Finding an Exotic Wave An exotic wave (J PC = 1 -+ ) was generated at level of 2.5 % with 7 other waves. Events were smeared, accepted, passed to PWA fitter.

13 Neutron/Proton Charge Form GeV (Polarization Experiments only) Here shown as ratio of Pauli & Dirac Form Factors F 2 and F 1, ln 2 (Q 2 / 2 )Q 2 F 2 /F 1 constant when taking orbital angular momentum into account (Ji)

14 Charged Pion Electromagnetic Form Factor applicability of pQCD (GPDs) to exclusive pion production ? Where does the dynamics of the q-q interaction make a transition from the strong (confinement) to the perturbative (QED-like) QCD regime? It will occur earliest in the simplest systems the pion form factor F (Q 2 ) provides our best chance to determine the relevant distance scale experimentally

15 with enough luminosity to reach the high-Q 2, high-x region! Counts/hour/ (100 MeV) 2 (100 MeV 2 ) for L=10 35 cm -2 sec -1 Access to the DIS 12 GeV

16 Extending DIS to High x 12 GeV will access the valence quark regime (x > 0.3) The Neutron Asymmetry A 1 (similar precision for p and d) The Neutron to Proton Structure Function Ratio CLAS: tagging spectator proton Hall C: 3H/3He 3 He(e,e)

17 E e =11 GeV NH 3 +He3 Flavor decomposition using SIDIS Valence quarks

18 Large flavor asymmetry in unpolarized sea Asymmetry in polarized sea? First data from HERMES compatible with zero but have large uncertainties Calculations: – Instantons ( QSM) – Pion cloud models ? Flavor decomposition: polarized sea (Goeke) More data expected from RHIC SSA in future

19 Beyond form factors and quark distributions – Generalized Parton Distributions (GPDs) Proton form factors, transverse charge & current densities Structure functions, quark longitudinal momentum & helicity distributions X. Ji, D. Mueller, A. Radyushkin ( ) Correlated quark momentum and helicity distributions in transverse space - GPDs

20 Kinematics for deeply excl. experiments no overlap with other existing experiments compete with other experiments

21 Q 2 = 5.4 GeV 2 x = t = 0.3 GeV 2 CLAS experiment E 0 = 11 GeV P e = 80% L = cm -2 s -1 Run time: 2000 hrs DVCS Single-Spin Asymmetry DVCS: Single Spin Asymmetry Many x, Q 2 and t values measured simultanously !

22 Projected results Spatial Image Projected precision in extraction of GPD H at x =

23 orbital angular momentum carried by quarks : solving the spin puzzle Ingredients: 1) GPD Modeling 2) HERMES 1 H(e,e )p (transverse target spin asymmetry) 3) Hall A 2 H(e,e n)p Compared to Lattice QCD At one value of x only k k'k' * q q'q' p p'p' e For quarks 12 GeV will give final answers

24 Exclusive 0 production on transverse target 2 (Im(AB*))/ T |A| 2 (1- 2 ) - |B| 2 ( 2 +t/4m 2 ) - Re(AB * )2 2 A UT = - Asymmetry depends linearly on the GPD E, which enters Jis sum rule. A ~ 2H u + H d B ~ 2E u + E d 0 K. Goeke, M.V. Polyakov, M. Vanderhaeghen, 2001 A ~ H u - H d B ~ E u - E d + A UT xBxB 0


26 Longitudinally polarized Target SSA for + Measurement of k T dependent twist-2 distribution provides an independent test of the Collins fragmentation. Efremov et al. Study the P T – dependence of A UL sin2 Study the possible effect of large unfavored Collins function. Real part of interfe- rence of wave functions with L=0 and L=1 quark kTkT In noncollinear single- hadron fragmentation additional FF H 1 (z,k T )

27 Transverse Target GeV A UT ~ Collins A UT ~ Sivers Simultaneous (with pion SIDIS) measurement of, exclusive with a transversely polarized target important to control the background. 11GeV (NH 3 ) f 1T, requires final state interactions + interference between different helicity states

28 Transversity in double pion production Dihadron production provides an alternative, background free access to transversity h1h1 h2h2 quark RTRT Collinear dihadron fragmentation described by two functions at leading twist: D 1 (z,cos R,M ),H 1 R (z,cos R,M ) The angular distribution of two hadrons is sensitive to the spin of the quark relative transverse momentum of the two hadrons replaces the P T in single-pion production (No transverse momentum of the pair center of mass involved ) Collins et al, Ji, Jaffe et al, Radici et al.

29 Observation that structure functions are altered in nuclei stunned much of the HEP community 23 years ago ~1000 papers on the topic; BUT more data are needed to uniquely identify the origin: What alters the quark momentum in the nucleus? Quark Structure of Nuclei: Origin of the EMC Effect x JLab 12 Jlab at 12 GeV Precision study of A- dependence Measurements at x>1 Polarized EMC effect Flavor-tagged (polarized) structure functions valence vs. sea contributions

30 12 GeV gives access to the high- x, high-Q 2 kinematics needed to find multi-quark clusters Correlated nucleon pair Six-quark bag (4.5% of wave function) Fe(e,e) 5 PAC days Multi-quark clusters are accessible at large x (>>1) and high Q 2 Mean field

31 (polarized EMC effect) Curve follows calculation by W. Bentz, I. Cloet, A. W. Thomas. g 1 (A) – Polarized EMC Effect New calculations indicate larger effect for polarized structure function than for unpolarized: scalar field modifies lower components of Dirac wave function Spin-dependent parton distribution functions for nuclei nearly unknown Can take advantage of modern technology for polarized solid targets to perform systematic studies – Dynamic Nuclear Polarization

32 Polarized EMC Effect – Flavor Tagging semi-inclusive DIS on polarized targets, measuring + and -, decompose to extract u A (x), d A (x). Challenging measurement, but have new tools: –High polarization for a wide variety of targets –Large acceptance to constrain syst. errors and tune models u A (x) u(x) x u v (x) free nucleon + scalar field + Fermi + vector field (total) d v (x) W. Bentz, I. Cloet, A. W. Thomas Ratios d A (x) d(x) nuclear matter

33 A PV Measurements A PV ~ 8 x Q to 100 ppm Steady progress in technology part per billion systematic control 1% normalization control JLab now takes the lead -New results from HAPPEX -Photocathodes -Polarimetry -Targets -Diagnostics -Counting Electronics E


35 DOE Generic Project Timeline We are here DOE CD-2 Reviews September 2007

36 Conceptual Design (CDR) - finished Research and Development (R&D) - ongoing 2006 Advanced Conceptual Design (ACD) - finished Project Engineering & Design (PED) - ongoing Construction – starts in ~18 months! Accelerator shutdown start mid 2012 Accelerator commissioning mid Pre-Ops (beam commissioning) Hall commissioning start late 2013 (based on funding guidance provided by DOE-NP in April 2007) 12 GeV Upgrade: Phases and Schedule

37 Summary The Jlab 12 GeV Upgrade will increase the energy of CEBAF, provide very high luminosities and will thus allow to measure with unprecedented precision: the high x behaviour of (un)polarised structure functions the spin and flavour decomposition in the valence region pion and nucleon form factors at high Q 2 single spin asymmetries and k t dependent effects deep exclusive processes in multi-differential form nuclear effects in (semi)-inclusive scattering search for hybrid states parity violating asymmetries as a test of the standard model The ideal laboratory for valence quark physics !


39 Quantum Numbers of Hybrid Mesons Quarks Excited Flux Tube Hybrid Meson like Exotic Flux tube excitation (and parallel quark spins) lead to exotic J PC

40 Mass (GeV) qq Mesons L = Each box corresponds to 4 nonets (2 for L=0) Radial excitations (L = qq angular momentum) exotic nonets 0 – – – 1 – + 1 – – 2 – – – + 2 – Glueballs Hybrids Meson Map Lattice GeV GeV GeV

41 Unraveling the Quark WNC Couplings 12 GeV: (2C 2u -C 2d )=0.01 PDG: ± 0.24 Theory: A V V A Vector quark couplingsAxial-vector quark couplings

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