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CLAS12 Initial Physics Program at the JLab 12 GeV Upgrade

Explore new frontiers in Hadron Physics with JLab's CLAS12 program, featuring cutting-edge equipment and high-precision measurements at 12 GeV and 9 GeV accelerators.

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CLAS12 Initial Physics Program at the JLab 12 GeV Upgrade

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  1. CLAS12 Initial Physics Program at the JLab 12 GeV Upgrade Volker Burkert Jefferson Lab 1st European CLAS12 Workshop, Feb. 25 – 28, Genova, Italia

  2. JLab Upgrade to 12 GeV Add new hall CHL-2 Enhance equipment in existing halls JLab Upgrade to 6 GeV Volker Burkert, CLAS12 Workshop, Genoa

  3. D C 9 GeV tagged polarized photons and a 4 hermetic detector Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles A High Resolution Spectrometer (HRS) Pair, and specialized large installation experiments New Capabilities in Halls A, B, & C, and a New Hall D B CLAS12 high luminosity, large acceptance. Volker Burkert, CLAS12 Workshop, Genoa

  4. A Program at the Forefront of Hadron Physics 3D Structure of the Nucleon Structure - the new Frontier in Hadron Physics Nucleon GPDs and TMDs – exclusive and semi-inclusive processes with high precision Precision measurements of structure functions and forward parton distributions at high xB Elastic & Transition Form Factors at high momentum transfer Hadronization and Color Transparency Hadron Spectroscopy – heavy baryons, hybrid mesons Volker Burkert, CLAS12 Workshop, Genoa

  5. CLAS12 CLAS12 Central Detector Forward Detector • GPDs & TMDs • Nucleon Spin Structure • N* Form Factors • Baryon Spectroscopy • Hadron Formation 2m Volker Burkert, CLAS12 Workshop, Genoa

  6. CLAS12 Institutions InstitutionFocus Area • Arizona State University (US) Beamline, Tagging System • Argonne National Laboratory (US) Cerenkov Counter • California State University (US) Cerenkov Counters • Catholic University of America (US) Software • College of William & Mary (US) Calorimetry, Magnet Mapping • Edinburgh University (UK) Software • Fairfield University (US) Polarized Target • Florida International University, Miami (US) Beamline/Moller polarimeter • Glasgow University (UK) Central Detector, DAQ, Forward Tagger, RICH • Grenoble University/IN2P3 (France) Central Detector • Idaho State University (US) Drift chambers • INFN –University Bari (Italy)tbd, interest in RICH • INFN –University Catania (Italy) tbd • INFN – Frascati and Fermi Center (Italy) Central Neutron Detector+ interest show in RICH • INFN –University Ferrara(Italy) (will join in 2010)tbd, interest in RICH • INFN – University Genoa (Italy) Central Neutron Detector+ interest in Forward Tagger • INFN – ISS/Rome 1 (Italy) tbd, interest in RICH • INFN – University of Rome Tor Vergata(Italy) Central Neutron Detector+ HD target • Institute of Theoretical and Experimental Physics (Russia) SC. Magnets, Simulations • James Madison University (US) Calorimetry • Kyungpook National University (Republic of Korea) CD TOF • Los Alamos National Laboratory (US) Silicon Tracker • Moscow State University, Skobeltsin Institute for Nuclear Physics (Russia) Software, SVT • Moscow State University (High Energy Physics) (Russia) Silicon Tracker • Norfolk State University (US) Preshower Calorimeter • Ohio University (US) Preshower Calorimeter • Orsay University/IN2P3 (France) Central Neutron Detector • Old Dominion University (US) Drift Chambers • Renselear Polytechnic Institute (US) Cerenkov Counters • CEA Saclay (France) Central Tracker, Reconstruction software • Temple University, Philadelphia (US) Cerenkov Counters • Thomas Jefferson National Accelerator Facility (US) Project coordination & oversight • University of Connecticut (US) Cerenkov Counters • University of New Hampshire (US) Central Tracker, Offline Software • University of Richmond (US) Offline Software • University of South Carolina (US) Forward TOF • University of Virginia (US) Beamline/Polarized Targets • Yerevan Physics Institute (Armenia) Calorimetry Volker Burkert, CLAS12 Workshop, Genoa

  7. CLAS12Central Detector Extension under development • Tracking w/ Micromegas • Neutron Detector Superconducting 5T Solenoid Magnet, 78cm ø warm bore. Central Time-of-Flight array (CTOF) Silicon Vertex Tracker Volker Burkert, CLAS12 Workshop, Genoa

  8. CLAS12– Central Detector SVT, CTOF • SVT - Charged particle tracking in 5T field • Vertex reconstruction • ΔT < 60psec in CTOF for particle id • Moller electron shield • Polarized target operation ΔB/B < 10-4 • in 3x5 cm cylinder around center CTOF 6 layers 8 layers SVT Volker Burkert, CLAS12 Workshop, Genoa

  9. CLAS12–HT Cerenkov Counter & Tracking Chambers DC’s IC Radiator gas: CO2 or Ar/Ne @1 atm π detection: p>4.9 GeV/c π rejection: >200 Mirror weight: < 200mg/cm2 DC: 36 layers iπ 3 regions, 6 sectors, 24,000 sense wires. IC: Calorimeter, 424 PbWO crystals Volker Burkert, CLAS12 Workshop, Genoa

  10. CLAS12– PID & Calorimetry FTOF Forward Carriage LTCC EC PCAL PCAL/EC: Electron, photon, neutron detection, high energy γ/π0 reconstruction. LTCC: Electron & pion separation. RICH: Needed for better Kaon id in some sectors. FTOF: Timing resolution ΔT<80ps Volker Burkert, CLAS12 Workshop, Genoa

  11. CLAS12 – Solenoid and Torus Magnets The B-field transverse to the particle trajectory is approximately matched to the average particle momentum. Volker Burkert, CLAS12 Workshop, Genoa

  12. CLAS12 Background Shielding Background at L=1032cm-2s-1, T = 150ns ΔT=150ns tracking chamber H2 Target No Magnetic Field Volker Burkert, CLAS12 Workshop, Genoa

  13. CLAS12 Background Shielding Background at L=1035cm-2s-1, T = 150ns Electrons Photons One random event 5 T Magnetic Field Volker Burkert, CLAS12 Workshop, Genoa

  14. CLAS12 Background Shielding Background at L=1035cm-2s-1, T = 150ns Electrons Photons Photons One Event One random event Shielding 5 T Magnetic Field and Shielding Volker Burkert, CLAS12 Workshop, Genoa

  15. 3-4 times better 8-10 times better CLAS12 - Forward tracking in DC+SVT The track obtained in the DC is extrapolated back to the last layer of the SVT. The algorithm then looks for a SVT track segment around this position (R=1cm) DC + SVT DC + SVT Large improvement of vertex determination Volker Burkert, CLAS12 Workshop, Genoa

  16. CLAS12–Design Parameters Forward Central Detector Detector Angular range Tracks 50 – 400 350 – 1250 Photons 2.50 – 400 --- Resolution dp/p (%) < 1 @ 5 GeV/c < 5 @ 1.5 GeV/c dq (mr) < 1 < 10 - 20 Df (mr) < 3 < 5 Photon detection Energy (MeV) >150 --- dq (mr)4 @ 1 GeV --- Neutron detection Neff < 0.7 (EC+PCAL) under development Particle ID e/p Full range --- p/p< 5 GeV/c < 1.25 GeV/c p/K < 2.5 GeV/c < 0.65 GeV/c K/p < 4 GeV/c < 1.0 GeV/c p0gg Full range --- hgg Full range --- L=1035cm-2s-1 Volker Burkert, CLAS12 Workshop, Genoa

  17. CLAS12 Initial Science Program Approved experiments correspond to about 5 years of scheduled beam operation . Volker Burkert, CLAS12 Workshop, Genoa

  18. 3-D Scotty by 2-D Scotty bx x 1-D Scotty Deeply Virtual Processes. GPDs & TMDs Water Calcium probablity Carbon Deep Inelastic Scattering & Forward Parton Distribution Functions. x x 3D NucleonStructureFrontier by Volker Burkert, CLAS12 Workshop, Genoa

  19. hard vertices g x+x x-x –t – Fourier conjugate to transverse impact parameter t Access to GPDs - Handbag Mechanism xB x = 2-xB GPDs depend on 3 variables, e.g. E(x, x, t). They probe the quark structure at the amplitude level. Deeply Virtual Compton Scattering (DVCS) x x – longitudinal quark momentum fraction 2x – longitudinal momentum transfer What is the physical content of GPDs? => talk by M. Vanderhaeghen Volker Burkert, CLAS12 Workshop, Genoa

  20. t=0:Ji’s Angular Momentum Sum Rule Physical content of GPD E & H Nucleon matrix element of the Energy-Momentum Tensor of QCD contains three scalar form factors (R. Pagels, 1965) and can be written as (X. Ji, 1997): M2(t) : Mass distribution inside the nucleon J (t) : Angular momentum distribution d1(t) : Forces and pressure distribution Directly measured in elastic Graviton scattering. GPDs are related to these form factors through 2nd moments To determine J(t) we need to measure thexand tdependence of GPDs. To separate M2(t) and d1(t) we need measurements at small and largeξ(xB). Volker Burkert, CLAS12 Workshop, Genoa

  21. H1, ZEUS Deeply Virtual Exclusive Processes - Kinematics Coverage of the 12 GeV Upgrade H1, ZEUS 27 GeV 11 GeV 11 GeV 200 GeV JLab Upgrade JLab @ 12 GeV COMPASS W = 2 GeV HERMES Study of high xB domain requires high luminosity 0.7 Volker Burkert, CLAS12 Workshop, Genoa

  22.  2 + - - + + - A = = Polarized beam, unpolarized target: ~ H(ξ,t) LU~ sin {F1H+ ξ(F1+F2)H+kF2E}d Kinematically suppressed Unpolarized beam, longitudinal target: ~ ~ UL~sin {F1H+ξ(F1+F2)(H+ξ/(1+ξ)E) -.. }d H(ξ,t) Kinematically suppressed Unpolarized beam, transverse target: E(ξ,t) UT~ cossin(s-){k(F2H – F1E) + …..}d Kinematically suppressed A path towards extracting of GPDs ξ~ xB/(2-xB) k = t/4M2 Volker Burkert, CLAS12 Workshop, Genoa

  23. Ds 2s s+ - s- s+ + s- A = = CLAS12 A path towards the extraction of GPDs e p epg Polarized electron beam DsLU~sinf{F1H+..}df Extract H(ξ,t) Volker Burkert, CLAS12 Workshop, Genoa

  24. Projected extraction of GPD Hat x = ξ Spatial Image Projected results Volker Burkert, CLAS12 Workshop, Genoa

  25. CLAS12 DVCS/BH Longitudinal Target Asymmetry e p epg Longitudinally polarized target ~ DsUL~sinfIm{F1H+x(F1+F2)H...}df ~ Extract H(ξ,t) Volker Burkert, CLAS12 Workshop, Genoa

  26. CLAS12 DVCS/BH Target Asymmetry e p epg Sample kinematics Q2=2.6 GeV2, xB = 0.25 Transverse polarized target DsUT~ sin(f-fs)cosfIm{k1(F2H–F1E)+…} df Extract E(ξ,t) (talk by M. Lowry on transverse target options) Volker Burkert, CLAS12 Workshop, Genoa

  27. The Promise of GPDs: 2-D &  3-D Images of the Proton d2 ∫ T (x,b ) = ei bEq(x, ) T (2)2 T T T Target polarization M. Burkardt uX(x,b ) dX(x,b ) T T Cat scan of the human brain Flavor dipole Shift depends on (x,b ) T Volker Burkert, CLAS12 Workshop, Genoa

  28. CLAS12 Transverse Momentum Distributions (talk by M. Anselmino) TMDs are complementary to GPDs in that they allow to construct 3-D images of the nucleon in momentum space TMDs are connected to orbital angular momentum (OAM) in the nucleon wave function – for a TMD to be non-zero OAM must be present. TMDs can be studied in experiments measuring azimuthal asymmetries or moments. Several proposals have been accepted by PAC34 that propose to upgrade CLAS12 with Kaon id => talks by H. Avakian, M. Contalbrigo, P. Rossi. Volker Burkert, CLAS12 Workshop, Genoa

  29. CLAS12 SIDIS on unpolarized protons. In inclusive electroproduction of pions the diff. cross section has an azimuthal modulation. dσ/dΩ = σT + εσL + εσTTcos2Φ + [ε(1+ε)]1/2σLTcosΦ 4 <Q2< 5 GeV2 The cos2Φ moment of the azimuthal asymmetry gives access to the Boer-Mulders Function which measures the momentum distribution of transversely polarized quarks in unpolarized nucleons. Volker Burkert, CLAS12 Workshop, Genoa

  30. CLAS12 SIDIS in double pol. asymmetry Transverse momentum dependence of longitudinally polarized quarks in longitudinally polarized protons. M.Anselmino et al Phys.Rev.D74:074015,2006 The double polarization asymmetry is sensitive to difference in the KT distribution of quarks with spin orientation parallel and anti-parallel to proton spin. • Current data not sensitive enough to clearly identify the effect. CLAS12 has much more sensitivity and reaches higher PT Volker Burkert, CLAS12 Workshop, Genoa

  31. CLAS12 SIDIS on Long. Polarized Target The sin2Φ moment gives access to the Kotzinian-Mulders function which measures the momentum distribution of transversely polarized quarks in the longitudinally polarized nucleon. • The sin2f moment is sensitive to spin-orbit correlations: the only leading twist azimuthal moment for longitudinally polarized target. Volker Burkert, CLAS12 Workshop, Genoa

  32. Proton Spin Puzzle ~ resolved ? Proton Spin: ½ = ½ ΔΣq + ΔG +OAM • ΔΣq = 0.33 +/- 0.03 +/- 0.05 • Recent results indicate that ΔG at x<0.1 is much smaller than what is needed to explain the “missing” spin. • There may be significant ΔG at x > 0.1 which is accessible at 12 GeV • CLAS12 can significantly improve the accuracy of the Q2 dependence of g1(x,Q2) at x>0.05 with precise double polarization data to determine ΔG(x) from QCD evolution equations. Volker Burkert, CLAS12 Workshop, Genoa

  33. CLAS12 Valence spin structure function Deuteron Proton W > 2; Q2 > 1 Accurate measurement of Q2 dependence is key for extraction of ΔG(x) Volker Burkert, CLAS12 Workshop, Genoa

  34. CLAS12 The Polarized Glue Gluon Polarization ΔG derived from QCD evolution of g1(x,Q2). LSS estimate of uncertainties in ΔG when projected CLAS12 data are included in fit. Volker Burkert, CLAS12 Workshop, Genoa

  35. CLAS12 Valence Quark Distribution d/u There is large uncertainty in the ratio d/u of down and up quark distributions at large x, due to large effects of nuclear wave function. This can be significantly improved by performing the measurement at kinematics where nuclear effects are under control. en(ps) → epsX Measure spectator proton to tag scattering of “free” neutron with small FSI. => talks by S. Stepanyan, K. Joo, on BONUS. Volker Burkert, CLAS12 Workshop, Genoa

  36. CLAS12 At 12 GeV extend knowledge of magnetic structure of neutron to much shorter distances. Needed for constraints of GPDs at large t. => talk by P. Kroll. Neutron Magnetic Form Factor Does the neutron magnetic structure differ from the proton? For Q2 < 5 GeV2 GMn deviates by less than 10% from the dipole form which also describes GMp with similar accuracy and up to much higher Q2. CLAS12can measure GMn simultaneously for Q2 ≤ 14 GeV2. Volker Burkert, CLAS12 Workshop, Genoa

  37. Charting the Dynamical Quark Mass QCD predicts dynamical generation of the momentum-dependent quark mass resulting from the gluon dressing of the quark propagator. per dressed quark Measurement of N* electrocouplings at Q2<12 GeV2 will explore the transition from the fully dressed quark mass to almost bare current quarks.. Volker Burkert, CLAS12 Workshop, Genoa

  38. CLAS published CLAS preliminary CLAS12projected CLAS12 N* Transitions @ 12 GeV Probe the transition from effective degrees of freedom to dynamical mass of dressed quarks. Volker Burkert, CLAS12 Workshop, Genoa

  39. CLAS12 Color transparency • ColorTransparency is a spectacular prediction of QCD: under the right conditions, nuclear matter will allow the transmission of hadrons with reduced attenuation • Unexpected in a hadronic picture of strongly interacting matter, but straightforward in quark gluon basis. • Small effects observed at lower energy. Expect significant effects at higher energy. eA→eρ0X CLAS12 projected Volker Burkert, CLAS12 Workshop, Genoa

  40. 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. Volker Burkert, CLAS12 Workshop, Genoa

  41. Summary • 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 hadrons by • accessing GPDs and TMDs • mapping the valence quark structure of nucleons with high precision • understanding hadronization processes • extending nucleon form factors to short distances • Design of accelerator and equipment upgrades are underway • Construction started October 2008, major procurements underway • Accelerator shutdown scheduled for 2012 => end of the 6 GeV program Volker Burkert, CLAS12 Workshop, Genoa

  42. This is a very exciting time for hadronic physics, and the perfect time for new collaborators to make significant contributions to the physics and equipment of CLAS12 Volker Burkert, CLAS12 Workshop, Genoa

  43. Volker Burkert, CLAS12 Workshop, Genoa

  44. CLAS12 Approved Experiments Volker Burkert, CLAS12 Workshop, Genoa

  45. CLAS12 Letters of Intent Volker Burkert, CLAS12 Workshop, Genoa

  46. Kinematics forγp → K+K+Ξ-*→Ξ-π0 (Ξ-→Λπ-, Λ→ pπ-) 1 2 Strange baryon spectroscopy – Search for cascade states Fast Kaon Slow Kaon Direct reconstruction of Ξ+* with tracking in FST/BST of detached vertices, e.g Ξ-→ Λπ-, Λ→ pπ- . Program will benefit from improved kaon identification. Volker Burkert, CLAS12 Workshop, Genoa

  47. CLAS12 DVCS protons in Barrel SVT epepγ Measurement of Generalized Parton Distributions Critical for tracking of recoil protons that occupy phase space at Lab angles greater than 35 degrees.  Volker Burkert, CLAS12 Workshop, Genoa

  48. SIDIS Kinematics at 11 GeV Volker Burkert, CLAS12 Workshop, Genoa

  49. CLAS12- Missing Mass Techniques ep → eL(pp-)X K K*(892) Volker Burkert, CLAS12 Workshop, Genoa

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