Hadron 2007, FrascatiOctober 11, 2007 1

1

The GlueX Project at Jefferson Lab

Zisis PapandreouGlueX Collaboration

University of Regina, Canada

G. Bali

D. Leinweber

Hadron 2007, FrascatiOctober 11, 2007 2

2

100 Physicists27 Institutions

6 Countries

Hadron 2007, FrascatiOctober 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)

Hadron 2007, FrascatiOctober 11, 2007 4

4

GlueX Music

Hadron 2007, FrascatiOctober 11, 2007 5

5

QCD and confinement

Large DistanceLow Energy

Small DistanceHigh Energy

Perturbative Non-Perturbative

Spectroscopy

GluonicDegrees of Freedom

Missing

High EnergyScattering

GluonJets

Observed

q

q

3-Jet

Hadron 2007, FrascatiOctober 11, 2007 6

6

Strong QCD in quark pairs and triplets

white

whiteNominally, glue isnot needed to describe hadrons.

Gluonic Excitations

Allowed systems: gg, ggg, qqg, qqqq Glueballs Hybrids Molecules

_ _ _

GlueX Focus: “light-quark mesons”u

d s

c

b

t

Hadron 2007, FrascatiOctober 11, 2007 7

7

Fun on the Lattice

G. Bali

Color Field: Gluons possess color charge: they couple to each other!

Flux

tube

forms

between

qq

Flux tubes realized in LQCD

D. Leinweber

linear potential

0.4 0.8 1.2 1.6

1.0

2.0

0.0

Vo(

r)

[GeV

]

r (fm)

Hadron 2007, FrascatiOctober 11, 2007 8

8

“Pluck” the Flux Tube

q

q

Normal meson:flux tube in ground state

m=0CP=(-1) S+1

How do we look for gluonic degrees of freedom in spectroscopy?

LSS12S = S + S12J = L + SC = (-1)L + SP = (-1)L + 1

Nonets characterized by given JPC

q

q

Hybrid meson:

flux tube in excited statem=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 JPC = 1– + or JPC=1+ – for the excited flux-tube

Hadron 2007, FrascatiOctober 11, 2007 9

9

Mas

s (G

eV)

1.0

1.5

2.0

2.5

qq Mesons

L = 0 1 2 3 4

Each box correspondsto 4 nonets (2 for L=0)

Radial excitations

(L = qq angular momentum)

exoticnonets

0 – +

0 + –

1 + +

1 + –

1– +

1 – –

2 – +

2 + –2 + +

0 – +

2 – +

0 + +

Glueballs

Hybrids

Meson Map

LQCD0++ 1.6 GeV1-+ 1.9 GeV

Hadron 2007, FrascatiOctober 11, 2007 10

10

Production of Hybrid Mesons

Hadron 2007, FrascatiOctober 11, 2007 11

11

Evidence for Exotic Hybrids

Much data in hand(exotic hybrids are suppressed)

q

q

aft

er

Quark spinsanti-aligned

orbeam

Hadron 2007, FrascatiOctober 11, 2007 12

12

•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

Partial Wave Analysis (PWA)

Hadron 2007, FrascatiOctober 11, 2007 13

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

aft

er

beam

Quark spinsaligned

Hadron 2007, FrascatiOctober 11, 2007 14

14

• 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…

Scientific Goals and Means

--

Hadron 2007, FrascatiOctober 11, 2007 15

15

6 GeV CEBAF

11

CHL-2CHL-2

12Upgrade magnets Upgrade magnets

and power and power suppliessupplies

Two 0.6 GeV linacs1.1

Beam Power: 1MWBeam Current 5 µA

Emittance: 10 nm-radEnergy Spread: 0.02%

Hadron 2007, FrascatiOctober 11, 2007 16

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

Hadron 2007, FrascatiOctober 11, 2007 17

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

Hadron 2007, FrascatiOctober 11, 2007 18

18

Tracking Subsystems

Cylindrical Drift Chamber

25 radial layers of tubes17 straight layers 4 +6o stereo layers 4 -6o stereo layersdE/dx for p· 450 MeV/c~3200 channels

r~ 150 m, z~2 mm

Forward Drift Chamber

4 identical packages24 layers of tubesCathode/wire/cathodeU&V strip planes~12000 channels

200 m resolution

Hadron 2007, FrascatiOctober 11, 2007 19

19

Forward and Rear Calorimeters

Forward Calorimeter (LGD)

4x4cm2 lead glass blocks(used in E852 and RadPhi)~2800 channels /E=7.3%/E + 3.6%

TOF Scintillator Wall250x6x2.54 cm3 bars~168 channels = sub 100ps

Upsteam Veto Calorimeter

Lead/scintillator based18 layers of scintillator56 238x4.25cm2 U, V layers8.9X0, 24% sampl. fraction~ few hundred channels

Hadron 2007, FrascatiOctober 11, 2007 20

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

Hadron 2007, FrascatiOctober 11, 2007 21

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!

Hadron 2007, FrascatiOctober 11, 2007 22

22

48 modules (phi sectors)

Barrel CalorimeterIn

ner

Layers

Inner layers (12cm depth): 4x6 array SiPMs: 2304 units

(0 or decay)

Ou

ter

Layers

Outer layers (10cm depth): 2x2 array PMTs: 384 units

- X0 = 1.45cm- Sampling Fraction = 11%- Prelim. /E=5.4%/E 1.5%

Hadron 2007, FrascatiOctober 11, 2007 23

23

SiPM Prototype Components

SensL Module3 x 3 mm2 sensor inTO-8 can

Heat sink

Amplifier (x20) board

Peltier board(+ Peltiercooler)

4 DC inputs: ±5 , (0-30 ),V Bias VGnd

( )SMA output

WiresFront Pair

( & )Red BlackPeltiercooler

4BackInner Pair

Thermistor

Outer PairSensor chip

Hadron 2007, FrascatiOctober 11, 2007 24

24

Ultrasonic bond - shear, flex absorption

Thermocompression bond - warping of flex, process

SA - IV Curve

SiPM Device Packaging

5 Phase-1PrototypesOn glass

Hadron 2007, FrascatiOctober 11, 2007 25

25

Physics Plans

• Detector commissioning• Physics commissioning: density matrices, a2(1320)• Exotic hybrid search

• ss physics, baryon spectroscopy, …

Hadron 2007, FrascatiOctober 11, 2007 26

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!

Hadron 2007, FrascatiOctober 11, 2007 27

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

2828

Hadron 2007, FrascatiOctober 11, 2007

Backup Slides

Hadron 2007, FrascatiOctober 11, 2007 29

29

flu

x

photon energy (GeV)

12 GeV electronsCoherent BremsstrahlungThis 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

diamondcrystal

Hadron 2007, FrascatiOctober 11, 2007 30

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 parityStates of linear polarization are eigenstates

of parity. States of circular polarization are not.

M

Hadron 2007, FrascatiOctober 11, 2007 31

31

Hadron 2007, FrascatiOctober 11, 2007 32

32

Fiber Spectra

• Two-step process: absorption and re-emission of light due to dopants 420nm

490nm

Hadron 2007, FrascatiOctober 11, 2007 33

33

Pixel: independent photon micro-counter in limited Geiger mode

4496 pixelsPDE=5.5%

Currently: A35H chip

6744 pixelsPDE=10.5%

Silicon PM Packaging

Breakdown bias: 25-30V

Gain: >106

Hadron 2007, FrascatiOctober 11, 2007 34

34

PE Spectrum

0

1

4

3

2

5

3x3 mm2 SiPMT

24.5 V (Δ =+1.2 )V V

-20C

Modified board 137with x gain

Hadron 2007, FrascatiOctober 11, 2007 35

35

pedestal

spe2 pe

SiPM Dark Current Run

pedestal

spe

2 pe

1

10

100

1000

104

0 50 100 150 200 250

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

Hadron 2007, FrascatiOctober 11, 2007 36

36

Winston Cone

Emission Facet

Device Coupling