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The GlueX Project at Jefferson Lab

The GlueX Project at Jefferson Lab. G. Bali. D. Leinweber. Zisis Papandreou GlueX Collaboration University of Regina, Canada. 100 Physicists 27 Institutions 6 Countries. 12 GeV/GlueX Project Update. 2004/03: CD-0 (mission need)

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The GlueX Project at Jefferson Lab

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  1. The GlueX Project at Jefferson Lab G. Bali D. Leinweber Zisis Papandreou GlueX Collaboration University of Regina, Canada 1

  2. 100 Physicists 27 Institutions 6 Countries 2

  3. 12 GeV/GlueX Project Update • 2004/03: CD-0 (mission need) • 2005/04: Scientific Review by ONP, “the scientific opportunity afforded by the 12 GeV upgrade is outstanding, … in studies of QCD and the quark structure of matter” • 2006/02: CD-1 (Preliminary Baseline Range) • 2006/08: PAC Proposals for 12 GeV • 2007/12: CD-2 (Performance Baseline) • 2008/12: CD-3 (Construction Start) • 2013: Beam delivery? • 2015: CD-4 (Start of Operations/Closeout) 3

  4. GlueX Music 4

  5. QCD and confinement High Energy Scattering Spectroscopy Gluon Jets Observed Gluonic Degrees of Freedom Missing 3-Jet Perturbative Non-Perturbative Asymptotic Freedom Confinement Large Distance Low Energy Small Distance High Energy 5

  6. white white _ _ _ Allowed systems: gg, ggg, qqg, qqqq Glueballs Hybrids Molecules Gluonic Excitations u c t GlueX Focus: “light-quark mesons” s d b Strong QCD in quark pairs and triplets Nominally, glue is not needed to describe hadrons. 6

  7. 2.0 1.0 linear potential 0.0 0.4 0.8 1.2 1.6 Fun on the Lattice Color Field: Gluons possess color charge: they couple to each other! Flux tubes realized in LQCD Vo( r) [GeV] r (fm) D. Leinweber G. Bali 7

  8. “Pluck” the Flux Tube Nonets characterized by givenJPC Normal meson:flux tube in ground state m=0 CP=(-1) S+1 Hybrid meson: flux tube in excited state m=1 CP=(-1) S In the first-excited state we have two degenerate transverse modes with J=1– clockwise and counter-clockwise – and their linear combinations lead toJPC = 1– +orJPC=1+ –for the excited flux-tube How do we look forgluonic degrees of freedomin spectroscopy? 8

  9. Meson Map qq Mesons Each box corresponds to 4 nonets (2 for L=0) 2 – + 0 – + 2 + + Hybrids 2 + – 2 – + 1 – – Glueballs 1– + exotic nonets 1 + – 1 + + 0 + – 0 – + 0 + + Mass (GeV) Radial excitations 2.5 2.0 1.5 LQCD 0++ 1.6 GeV 1-+ 1.9 GeV 1.0 (L = qq angular momentum) L = 0 1 2 3 4 9

  10. Production of Hybrid Mesons 10

  11. q after q Evidence for Exotic Hybrids Much data in hand (exotic hybrids are suppressed)  or beam Quark spins anti-aligned 11

  12. Partial Wave Analysis (PWA) • Bump hunting in cross section data is inadequate to the task • Need PWA: • Identify the JPC of a meson • Determine production amplitudes & mechanisms • Include polarization of beam, target, spin and parity of resonances and daughters, relative angular momentum. • GlueX experience: • E852, Crystal Barrel, CLAS; new independent code being developed 12

  13. q q after Photocouplings & Phenomenology gbeam Quark spins aligned • Couplings virtually unknown even for conventional mesons • Testbed: by the time GlueX runs expect all predictions to be tested by Lattice QCD • Phenomenology: • isobar model widely used in multi-particle N N states; it is not completely general • factorized approach has limitations: e.g. Deck effect where we get threshold peak in isobar  S-wave 13

  14. Scientific Goals and Means • Definitive and detailed mapping of hybrid meson spectrum • Search for smoking gun signature of exotic JPC hybrid mesons; these do not mix with qq states • ss and baryon spectroscopy, … • Tools for the GlueX Project: • Accelerator: 12 GeV electrons, 9 GeV tagged, linearly polarized photons with high flux • Detector: hermiticity, resolution, charged and neutrals • PWA Analysis: spin-amplitude of multi-particle final states • Computing power: 1 Pb/year data collection, databases, distributed computing, grid services… - - 14

  15. Upgrade magnets and power supplies CHL-2 12 11 6 GeV CEBAF Two 0.6 GeV linacs 1.1 Beam Power: 1MW Beam Current 5 µA Emittance:10 nm-rad Energy Spread: 0.02% 15

  16. Ideal Photon Beam Energy • Figure of Merit: • - Start with 12 GeV electrons • Meson yield for high mass region • Separate meson from baryon resonances • Balance beam flux/polarization • Coherent bremsstrahlung, tagger, collimator 16

  17. GlueX Detector • Design is mature: • based on 7 years of R&D on subsystems • ideally matched to 9 GeV photon beam • Magnet: • 2 Tesla superconducting solenoid • Beam tests: • - BCAL, FDC, TOF 17

  18. Cylindrical Drift Chamber 25 radial layers of tubes 17 straight layers 4 +6o stereo layers 4 -6o stereo layers dE/dx for p· 450 MeV/c ~3200 channels r~ 150 m, z~2 mm Forward Drift Chamber 4 identical packages 24 layers of tubes Cathode/wire/cathode U&V strip planes ~12000 channels 200 m resolution Tracking Subsystems 18

  19. Forward Calorimeter (LGD) 4x4cm2 lead glass blocks (used in E852 and RadPhi) ~2800 channels /E=7.3%/E + 3.6% TOF Scintillator Wall 250x6x2.54 cm3 bars ~168 channels  = sub 100ps Upsteam Veto Calorimeter Lead/scintillator based 18 layers of scintillator 56 238x4.25cm2 U, V layers 8.9X0, 24% sampl. fraction ~ few hundred channels Forward and Rear Calorimeters 19

  20. Decay Photon Distributions • Detecting ’s and ’s is essential for GlueX • Pythia simulations • 28% of photons in FCAL • 70% of decay photons are captured by BCAL • 50% of BCAL ones have energies < 300MeV • BCAL has a large workload • FCAL-BCAL handoff (100-120) important 20

  21. - 0.5 mm lead sheets • 1mm scintillating fibers • optical epoxy • 210 layers Module Construction BCAL design modeled after KLOE EMC; Our thanks to INFN Frascati & Pisa Groups! 21

  22. Outer Layers  Inner layers (12cm depth): 4x6 array SiPMs: 2304 units Inner Layers Outer layers (10cm depth): 2x2 array PMTs: 384 units Barrel Calorimeter 48 modules (phi sectors) (0 or  decay) - X0 = 1.45cm • Sampling Fraction = 11% • Prelim. /E=5.4%/E 1.5% 22

  23. SiPM Prototype Components 23

  24. Ultrasonic bond - shear, flex absorption Thermocompression bond - warping of flex, process 5 Phase-1 Prototypes On glass SA - IV Curve SiPM Device Packaging 24

  25. Physics Plans • Detector commissioning • Physics commissioning: density matrices, a2(1320) • Exotic hybrid search  • ss physics, baryon spectroscopy, … 25

  26. Summary • The nature of confinement is an outstanding and fundamental question of quarks and gluons in QCD. • Lattice QCD and phenomenology strongly indicate that the gluonic field between quarks forms flux-tubes and that these are responsible for confinement. • The excitation of the gluonic field leads to an entirely new spectrum of mesons and their properties are predicted by lattice QCD. Data are needed to validate these predictions. • PWA and improved theoretical understanding is required. The definitive experiment for this search will be GlueX at the energy-upgraded JLab. If exotic hybrids are there, we will find them! We welcome new collaborators! 26

  27. References/Acknowledgments • G. Bali, U. Glasgow • D. Leinweber, CSSM / U. Adelaide • A. Dzierba, U. Indiana • C. Meyer, CMU • J. Dudek, JLab • portal.gluex.org • www.halld.org • www.gluex.org 27

  28. Backup Slides 28

  29. Coherent Bremsstrahlung Incoherent & coherent spectrum 40% polarization in peak collimated tagged with 0.1% resolution 12 GeV electrons flux This technique provides requisite energy, flux and polarization photons out electrons in spectrometer diamond crystal photon energy (GeV) 29

  30. Linear Polarization • Linear polarization is: • Essential to isolate the production mechanism (M) if X is known • A JPC filter if M is known (via a kinematic cut) • Degree of polarization is directly related to required statistics • Linear polarization separates natural and unnatural parity States of linear polarization are eigenstates of parity. States of circular polarization are not. M 30

  31. 31

  32. 420nm 490nm Fiber Spectra • Two-step process: absorption and re-emission of light due to dopants 32

  33. Silicon PM Packaging Pixel: independent photon micro-counter in limited Geiger mode Breakdown bias: 25-30V Gain: >106 4496 pixels PDE=5.5% 6744 pixels PDE=10.5% Currently: A35H chip 33

  34. PE Spectrum 34

  35. PE Spectrum Reduction in DR - Optical isolation (trenching) - Cooling - Threshold over 1pe - V+ relaxation Dark Current - Dominated by single-pixel thermal carrier events - Causes shifts in pedestals based on E and no of readout cells fired 35

  36. Device Coupling Winston Cone Emission Facet 36

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