Seema Dhamija for the GLUEX collaboration Florida International University Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Physics Goals Meson Spectroscopy Gluonic Excitations Current Evidence The Next Generation Experiment Jlab Upgrade and GlueX Summary Physics Goals Meson Spectroscopy Gluonic Excitations Current Evidence The Next Generation Experiment Jlab Upgrade and GlueX Summary Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

 The goal of the GlueX experiment is to map out the spectrum of exotic hybrid mesons In the light quark sector. The experimental information about this spectrum is essential In addressing one of the fundamental issues in physics : A detailed understanding of the nature of the confinement of quarks and gluons in QCD.  Flux tubes lead to a linear, confining potential. Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

→ → → S = S 1 + S 2 → → → J = L + S P = (-1) L+1 C = (-1) L+S J PC = 0 -+ : π, KJ PC = 1 -- : ρ, K *, γ With three light quarks the conventional mesons form flavor nonets – for each J PC Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

How do we look for gluonic degrees of freedom in spectroscopy? The flux tube model provides us with a framework within which we can understand gluonic excitations and their properties. When the flux tube is in its ground state – conventional mesons occur. When the flux tube is excited, hybrid mesons result. Normal mesons: glue is passive Hybrid mesons: glue is excited First excited state :  Two degenerate transverse modes with J = 1 (clockwise and counter-clockwise)  Linear combinations lead to J PC = 1 -+ or J PC = 1 +- for excited flux tube The quantum numbers of the excited flux tube, when combined with those of the quarks can lead to exotic quantum numbers. Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

J PC = 1 -- or 1 ++ L = 0, S = 0 J PC = 0 -+, 1 +-, 2 -+ J PC = 0 +-, 1 -+, 2 +- L = 0, S = 1 exotic Photoproduction more likely to produce exotic hybrids J PC = 0 -+ : π, K Ground State J PC = 1 -- : ρ, K *, γ Excited State J PC = 1 +- or 1 -+ Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Flux – tube model: 8 degenerate nonets 1 ++, , 0 +-, 1 -+, 1 +-, 2 -+, 2 +- ~ 1.9 GeV/c 2 S=0 S=1 Lattice calculations nonet is the lightest Collab.1 -+ Mass (GeV/c 2 ) UKQCD (97)1.87 ± 0.20 MILC (97)1.97 ± 0.30 MILC (99)2.11 ± 0.10 SESAM (98)1.9± 0.20 Mei(03)2.01 ± 0.10 Bernard (04)1.79 ± 0.14 ~ 2.0 GeV/c Splitting ≈ 0.20 →GlueX wants to map out the hybrid mesons ← Measurement of the excited QCD potential The ‘S+P’ selection rule for hybrid decays leads to complicated decay modes of hybrids- which could explain why they have not been seen earlier. Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Have gluonic excitations been observed? π 1 (1400) : π – p → η π – p (18 GeV) (E852) Crystal Barrel : antiproton-neutron annihilation Same strength as the a 2. PDG value M = 1376 ± 17 MeV, Г = 300 ± 40 MeV. Decays: only ηπ Π 1 (1600) : π – p → ρp → π + π – π – p (E852) Decays ρπ, η’π, f 1 π, b 1 π Only seen in πp production, (E852+VES) PDG value M= 1596 MeV, Г = 312 MeV. Π 1 (2000) : Weak evidence in preferred hybrid modes f 1 π and b 1 π Needs confirmation. These states are not without controversy and thedecay modes are not what is expected. Revisiting π 1 (1600) → ρπ Dzierba et al. PRD 73 (2006) No evidence for the π 1 (1670). Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

 Evidence is tantalizing but not strong.  In a nonet, there should only be one π 1 state.  Unambiguous discovery of exotic hybrid mesons requires a detailed knowledge of the full meson spectrum and understanding of multiple decay modes.  Exotic states are expected to be relatively broad.  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  Assumptions in amplitude analyses must be well understood and controlled.  Need PWA Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

 Detector Large & uniform acceptance Good calorimetry (multiple γ s ) Good momentum resolution Charged particle ID Handle high luminosity  γ - beam (σ exotic -meson ) High enough in energy (to produce hybrids) High luminosity Linearly polarized (parity) Diffractive production N: J P = 0 +, 1 -, 2 +, ……. Exotic production U: J P = 0 -, 1 +, 2 -, ……. Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

-why is the photon so special?  Π beam Π with excited flux tube : m=1, S=0, L=0, J=1 J PC = Quark spin flip → exotic hybrids BUT σ exotic-meson reduced (« σ meson ) Lot of data but little evidence for hybrids  γ beam qq with excited flux tube : m=1, S=, L=0, J=0,1,2 J PC = σ exotic-meson ≈ σ meson Almost no data available Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Continuous-wave (1497 MHz, 2ns bunch structure In halls) Polarized electron beam Upgrading to 12 GeV (from 6 GeV) 70 μA 12 GeV (200 μA 6GeV)  Electron beam accelerator Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

~100meters Construction has recently begun and will be completed Fall (Buildings only, detectors will follow) Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

4 1.5T dipole magnet 12m long vacuum chamber e-e- 20  m diamond radiator photon energy (GeV) coherent bremstrahlung spectrum Microscope: Movable to cover different energy ranges 100 x 5 scintillating fibers (2mm x 2mm) 800MeV covered by whole microscope 100MHz tagged  /sec on target ~8MeV energy bite/column Fixed array hodoscope: 190 scintillators 50% coverage below 9GeV  100% coverage above 9GeV  Tags GeV  ~30MeV energy bite/counter 3.5 – 17 MHz/counter Photon Polarization: 20  m diamond radiator Coherent peak is linearly polarized ~40% polarization with 9GeV Peak location tunable with diamond angle Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

2.2 Tesla Solenoid 2.2 T superconducting solenoidal magnet Fixed target (LH 2 ) 10 8 tagged γ/s ( GeV) hermetic Charged particle tracking Central drift chamber (straw tube) Forward drift chamber (cathode strip) Calorimetry Barrel Calorimeter (lead, fiber sandwich) Forward Calorimeter (lead-glass blocks) PID Time of Flight wall (scintillators) Start counter Barrel Calorimeter Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Electronics All digitization electronics are fully pipelined (VME64x-VXS)  F1TDC (60 ps, 32 ch. or 115 ps 48 ch.)  125 MHz fADC (12 bit, 72 ch.)  250 MHz fADC (12 bit, 16 ch.) Trigger latency ~3  s 3GB/s readout from front end 300MB/s to mass storage 3PB/yr to tape Offline software C++ object oriented framework (JANA) Multi-threaded event processing Highly modular through use of templates Crate Trigger Processor F1TDC Level 1 trigger test stand Signal distribution board Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Understanding confinement requires an understanding of the glue that binds quarks into hadrons. Hybrid mesons are perhaps the most promising laboratory. Future studies with the GlueX experiment at Jlab, provide the hope for improved experimental results and interpretations. Photoproduction promises to be rich in hybrids, starting with those having exotic quantum numbers where little or no data exist. The GlueX experiment will provide for the detailed spectroscopy necessary to map out the hybrid meson spectrom. Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Barrel Calorimeter: 191 layer Pb-scintillating fiber sandwich (15.5X o ) 12.5% sampling fraction = 1344 readout sections/end  E /E= (5.54/√E 1.6) %  z = 5mm/√E  t = 74ps/√E 33ps angular coverage 11 o <  < 120 o Forward Calorimeter: 2800 F8-00 and F108 (center) Pb-glass blocks 4cm x 4cm x 45cm  E /E= (5.7/√E 2.0) %  xy = 6.4mm/√E angular coverage 2 o <  < 11 o Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Central Drift Chamber: 3522 straw tubes (1.6cm diameter) 12 axial layers, 16 stereo layers (6 o ) dE/dx for p< 450 MeV/c  r = 150  m angular coverage 6 o <  <155 o Forward Drift Chamber: 4 packages, 6 planes/package, 96 wires/plane (2304 sense wires) cathode strip readout (48 planes x 216 strips/plane = 10,368 strips)  r = ~200  m perpendicular to wire (drift time)  s = ~200  m along wire (cathode strips) angular coverage 1 o <  <30 o  p /p : %   : mrad   : 2 – 3 mrad Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

 diff (ps)  p separation <450MeV/c  K separation <275MeV/c Barrel Calorimeter Forward TOF  diff (ns) ~200 ps ~80 ps CDC dE/dx 40 scintillators 300 ps (w/tracking) Used for start-up Start Counter Particle ID is done primarily through time of flight with some help from dE/dx in chambers. Space is left in design for a future PID detector. Beam Test Data Expected Separation Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

5/29/09 CIPANP The GlueX Detector -- David Lawrence (JLab) 23 Page 23 CapabilityQuantityRange Charged particles Coverage 1 o <  < 160 o Momentum Resolution (5 o -140 o )  p /p = 1 − 3% Position resolution  ~  m dE/dx measurements 20 <  < 160 o Time-of-flight measurements  ToF ~ 60 ps;  BCal ~ 200ps Barrel time resolution  t  < (74 /√E 33) ps Photon detection Energy measurements 2 o <  < 120 o LGD energy resolution (E > 60 MeV)  E /E = (5.7/√E 2.0)% Barrel energy resolution (E > 60 MeV)  E /E =(5.54/√E 1.6)% LGD position resolution  x,y, ~ cm/√E Barrel position resolution  z ~ 0.5cm /√E DAQ/trigger Level 1 < 200 kHz Level 3 event rate to tape ~ 15 kHz Data rate 300 MB/s Electronics Fully pipelined 250 / 125 MHz fADCs, TDCs Photon Flux Initial: 10 7  /s Final: 10 8  /s Hall D: Detector Design Parameters

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Start Counter Which tagged e - belongs to γ? Level-1 hardware trigger Array of ~ 40 scintillators with bent ends Read out by high field (fine mesh) PMT 500 mm Straight mm bended (35 o ) Maximal solid angle coverage High rate capability Energy and timing measurements Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

 X = Y = 0, Z = 65 cm Electromagnetic Background Hadronic Events Signal Events Electromagnetic Background Hadronic Events Signal Events Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Hit Multiplicity Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Hit Occupancy Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Total Rate 10.5 MHz – 1cm 3.7 MHz – 2 cm Total Rate 10.5 MHz – 1cm 3.7 MHz – 2 cm Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Studied SC acceptance for events produced by ordinary photoproduction Processes (PYTHIA) Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Start counter hit multiplicity as a function of photon beam energy Start counter hit multiplicity as a function of photon beam energy SC hit multiplicity, E γ > 8 GeV Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Proton required to have a hit in the SC Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009

Seema Dhamija QNP09, IHEP, Beijing – 22/09/2009