1. Hadron 2007, Frascati October 11, 2007 1 1 The GlueX Project at Jefferson Lab Zisis Papandreou GlueX Collaboration University of Regina, Canada G. Bali D. Leinweber

2. Hadron 2007, Frascati October 11, 2007 2 2 100 Physicists 27 Institutions 6 Countries

3. Hadron 2007, Frascati October 11, 2007 3 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)

4. Hadron 2007, Frascati October 11, 2007 4 4 GlueX Music

5. Hadron 2007, Frascati October 11, 2007 5 5 QCD and confinement Large Distance Low Energy Small Distance High Energy PerturbativeNon-Perturbative Spectroscopy Gluonic Degrees of Freedom Missing High Energy Scattering Gluon Jets Observed 3-Jet

6. Hadron 2007, Frascati October 11, 2007 6 6 Strong QCD in quark pairs and triplets white Nominally, glue is not needed to describe hadrons. Gluonic Excitations Allowed systems: gg, ggg, qqg, qqqq GlueballsHybridsMolecules _ _ _ GlueX Focus: “light-quark mesons” u d s c b t

7. Hadron 2007, Frascati October 11, 2007 7 7 Fun on the Lattice G. Bali Color Field: Gluons possess color charge: they couple to each other! Flux tubes realized in LQCD D. Leinweber linear potential 0.40.81.21.6 1.0 2.0 0.0 V o ( r) [GeV] r (fm)

8. Hadron 2007, Frascati October 11, 2007 8 8 “Pluck” the Flux Tube Normal meson: flux tube in ground state m=0 CP=(-1) S+1 How do we look for gluonic degrees of freedom in spectroscopy? Nonets characterized by given J PC 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 to J PC = 1 – + or J PC =1 + – for the excited flux-tube

9. Hadron 2007, Frascati October 11, 2007 9 9 Mass (GeV) 1.0 1.5 2.0 2.5 qq Mesons L = 01234 Each box corresponds to 4 nonets (2 for L=0) Radial excitations (L = qq angular momentum) exotic nonets 0 – + 0 + – 1 + + 1 + – 1 – + 1 – – 2 – + 2 + – 2 + + 0 – + 2 – + 0 + + Glueballs Hybrids Meson Map LQCD 0 ++ 1.6 GeV 1 -+ 1.9 GeV

10. Hadron 2007, Frascati October 11, 2007 10 Production of Hybrid Mesons

11. Hadron 2007, Frascati October 11, 2007 11 Evidence for Exotic Hybrids Much data in hand (exotic hybrids are suppressed) q q after Quark spins anti-aligned  or  beam

12. Hadron 2007, Frascati October 11, 2007 12 Bump hunting in cross section data is inadequate to the task Need PWA: Identify the J PC 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 Partial Wave Analysis (PWA)

13. Hadron 2007, Frascati October 11, 2007 13 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 Photocouplings & Phenomenology q q after  beam Quark spins aligned

14. Hadron 2007, Frascati October 11, 2007 14 Definitive and detailed mapping of hybrid meson spectrum Search for smoking gun signature of exotic J PC 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… Scientific Goals and Means - -

15. Hadron 2007, Frascati October 11, 2007 15 6 GeV CEBAF 11CHL-2 12 Upgrade magnets and power supplies Two 0.6 GeV linacs 1.1 Beam Power: 1MW Beam Current 5 µA Emittance: 10 nm-rad Energy Spread: 0.02%

16. Hadron 2007, Frascati October 11, 2007 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

17. Hadron 2007, Frascati October 11, 2007 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

18. Hadron 2007, Frascati October 11, 2007 18 Tracking Subsystems Cylindrical Drift Chamber 25 radial layers of tubes 17 straight layers 4 +6 o stereo layers 4 -6 o 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

19. Hadron 2007, Frascati October 11, 2007 19 Forward and Rear Calorimeters Forward Calorimeter (LGD) 4x4cm 2 lead glass blocks (used in E852 and RadPhi) ~2800 channels  /E=7.3%/  E + 3.6% TOF Scintillator Wall 250x6x2.54 cm 3 bars ~168 channels  = sub 100ps Upsteam Veto Calorimeter Lead/scintillator based 18 layers of scintillator 56 238x4.25cm2 U, V layers 8.9X 0, 24% sampl. fraction ~ few hundred channels

20. Hadron 2007, Frascati October 11, 2007 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 (10 0 -12 0 ) important

21. Hadron 2007, Frascati October 11, 2007 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!

22. Hadron 2007, Frascati October 11, 2007 22  48 modules (phi sectors) Barrel Calorimeter Inner Layers Inner layers (12cm depth): 4x6 array SiPMs: 2304 units (  0 or  decay) Outer Layers Outer layers (10cm depth): 2x2 array PMTs: 384 units - X 0 = 1.45cm - Sampling Fraction = 11% - Prelim.  /E=5.4%/  E  1.5%

23. Hadron 2007, Frascati October 11, 2007 23 SiPM Prototype Components

24. Hadron 2007, Frascati October 11, 2007 24 Ultrasonic bond - shear, flex absorption Thermocompression bond - warping of flex, process SA - IV Curve SiPM Device Packaging 5 Phase-1 Prototypes On glass

25. Hadron 2007, Frascati October 11, 2007 25 Physics Plans Detector commissioning Physics commissioning: density matrices, a 2 (1320) Exotic hybrid search ss physics, baryon spectroscopy, … 

26. Hadron 2007, Frascati October 11, 2007 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. We welcome new collaborators! The definitive experiment for this search will be GlueX at the energy-upgraded JLab. If exotic hybrids are there, we will find them!

27. Hadron 2007, Frascati October 11, 2007 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

28. Hadron 2007, Frascati October 11, 2007 28 Backup Slides

29. Hadron 2007, Frascati October 11, 2007 29 flux photon energy (GeV) 12 GeV electrons Coherent Bremsstrahlung This technique provides requisite energy, flux and polarization collimated Incoherent & coherent spectrum tagged with 0.1% resolution 40% polarization in peak electrons in photons out spectrometer diamond crystal

30. Hadron 2007, Frascati October 11, 2007 30 Linear Polarization Linear polarization is: Essential to isolate the production mechanism (M) if X is known A J PC 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

31. Hadron 2007, Frascati October 11, 2007 31

32. Hadron 2007, Frascati October 11, 2007 32 Fiber Spectra Two-step process: absorption and re- emission of light due to dopants 420nm 490nm

33. Hadron 2007, Frascati October 11, 2007 33 Pixel: independent photon micro-counter in limited Geiger mode 4496 pixels PDE=5.5% Currently: A35H chip 6744 pixels PDE=10.5% Silicon PM Packaging Breakdown bias: 25-30V Gain: >10 6

34. Hadron 2007, Frascati October 11, 2007 34 PE Spectrum

35. Hadron 2007, Frascati October 11, 2007 35 PE Spectrum Dark Current - Dominated by single-pixel thermal carrier events - Causes shifts in pedestals based on E  and no of readout cells fired Reduction in DR - Optical isolation (trenching) - Cooling - Threshold over 1pe - V + relaxation

36. Hadron 2007, Frascati October 11, 2007 36 Winston Cone Emission Facet Device Coupling