THE EXPERIMENT - Curtis A. Meyer Home Page · YM glueball negative parity ... radiator. • Polarization parallel and perpendicular to floor. ... 240 Wire Position Resolution [µm]

THE EXPERIMENT

Curtis A. Meyer Carnegie Mellon

The GlueX Collaboration Arizona State, Athens, Carnegie Mellon, Catholic University, Univ. of Connecticut, Florida International, Florida State, George Washington, Glasgow, GSI, Indiana University, ITEP, Jefferson Lab, U. Mass Amherst, MIT, MePhi, Norfolk State, North Carolina A&T, Univ. North Carolina Wilmington, Northwestern, Santa Maria, University of Regina, Tomsk and Yerevan Physics Institute. Over 120 collaborators from 24 institutions with others joining and more are welcome.

June 4, 2016 Meson 2016 - C.A. Meyer 2

Outline • The GlueX physics program. • The GlueX experiment and its performance during commissioning.

• Expected initial physics from GlueX. • Future plans and other physics. • Summary.


12-GeV beam, Dec.2015

Quantum Chromo Dynamics June 4, 2016 Meson 2016 - C.A. Meyer 4

QCD describes the interactions of quarks and gluons and should predict the spectrum of bound-state baryons ( ) and mesons ( ). There should also be mesons in which the gluonic field contributes directly to the JPC quantum numbers of the states --- hybrid mesons. Some are expected to have ``exotic’’ quantum numbers.

qqqqq

Lattice QCD calculation of the light-quark meson spectrum. ``Constituent gluon’’: JPC = 1+-

mass of 1-1.5 GeV. The lightest hybrid nonets 1--, (0-+,1-+, 2-+)

0.5

1.0

1.5

2.0

2.5

exotics

isoscalar

isovector

YM glueball

negative parity positive parity

? ud

ss

uu

2.0GeV

0+- 2+- 1-+

2.5Gev

Lattice QCD June 4, 2016 Meson 2016 - C.A. Meyer 5

0.5

1.0

1.5

2.0

2.5

exotics

isoscalar

isovector

YM glueball


Light-quark Mesons (u,d,s)

1p2

�uu� dd

� 1p2

�uu+ dd

�(ss)

PRD83, 111502 & PRD88, 094505

Lattice QCD June 4, 2016 Meson 2016 - C.A. Meyer 6

0.5

1.0

1.5

2.0

2.5

exotics

isoscalar

isovector

YM glueball


Light-quark Mesons (u,d,s)

1p2

�uu� dd

� 1p2

�uu+ dd

�(ss)

States with non-trivial gluonic fields. Fj,µ⌫ F

µ⌫j

1--

0-+

2-+ 1-+

1--, 0-+ , 1-+ , 2-+

Supermultiplet

PRD83, 111502 & PRD88, 094505


QCD Exotics

π1 IG(JPC)=1-(1-+)

η’1 IG(JPC)=0+(1-+)

η1 IG(JPC)=0+(1-+)

K1 IG(JPC)= ½ (1-)

La#ceQCDsuggests5nonetsofmesonswithexo7cquantumnumber: 1nonetof0+-exo7cmesons2nonetsof1-+exo7cmesons2nonetsof2+-exo7cmesons

⇡1

⌘1

Experimentalevidenceexistsforπ1states.

``Constituent gluon’’ behaves like JPC = 1+- with a mass of 1-1.5 GeV The lightest hybrid nonets: 1--, (0-+,1-+, 2-+)

0.5

1.0

1.5

2.0

2.5

exotics

isoscalar

isovector

YM glueball


? ud

ss

uu

2.0GeV

0+- 2+- 1-+

2.5Gev

Kaon states do not have exotic QNs

PRD84, 074023

Photoproduction Mechanisms June 4, 2016 Meson 2016 - C.A. Meyer 8

ρ,ω,φγ

p N

X

π,η,ρ,ω,P,...

Simple quantum number counting for production: (IG)JPC up to L=2

ρπ,ρω π1ωω,ρρ η1

ωω,ρρ,φω η’1 ρP b0 ωP h0 ωP, φP h’0 ωπ,ρη,ρP b2 ρπ,ωη,ωP h2 ρπ,ωη,φP h’2

ρπ is charge-exchange only

Can couple to all the lightest exotic hybrid nonets through photoproduction and VMD. Linear polarization is a filter on the naturality of the exchanged particle.

P = Pomeron exchange


Hybrid kaons do not have exotic QN’s

Decay Modes of Exotic Hybrids π1 → πρ, πb1 , πf1,πη’, ηa1 η1 → ηf2,a2π,ηf1, ηη’,π(1300)π, a1π, η1’→ K*Κ, Κ1(1270)Κ, Κ1(1410)Κ , ηη’

b2 → ωπ, a2π, ρη, f1ρ, a1π, h1π, b1η h2 → ρπ,b1π,ωη, f1ω h’2 → Κ1(1270)Κ, Κ1(1410)Κ, K2

*Κ, φη, f1φ

b0 → π(1300)π , h1π, f1ρ, b1ηh0 → b1π , h1η h’0 → K1(1270)Κ, Κ(1460)Κ, h1η

Early Reach With Statistics Hard Models suggest narrower states are in the spin-1 and spin-2 nonets, while the spin-0 nonets are broad.

The GlueX Experiment June 4, 2016 Meson 2016 - C.A. Meyer 10

barrelcalorimeter

time-of-flight

forward calorimeter

photon beam

electronbeamelectron

beam

superconductingmagnet

target

tagger magnet

tagger to detector distanceis not to scale

diamondwafer

GlueX

central driftchamber

forward driftchambers

Photo Production of Hybrids, Light-quark Mesons and Strangeonium States

Initial Physics in 2016

BaBar DIRC Bars


75 m

Collimator select � < 25 �r

polarized photons Hall-D

Diamond Radiator "↑− "%→&"↑− %

Tagger Area

Photon Tagger Pair Spectrometer

GlueX Spectrometer

Photon Beam Dump

Electron Beam Dump East ARC

North LINAC

•  12 GeV e- beam up to 2.2 µA. •  Linearly polarized photons (Pɣ≈40%) from

coherent bremsstrahlung on thin diamond radiator.

•  Polarization parallel and perpendicular to floor.

•  Design intensity of 108 ɣ/s in coherent peak (Eɣ = 8.4-9 GeV)

Polarimeter

Goniometer with diamonds


75 m

Collimator select � < 25 �r

polarized photons Hall-D

Diamond Radiator "↑− "%→&"↑− %

Tagger Area

Photon Tagger Pair Spectrometer

GlueX Spectrometer

Photon Beam Dump

Electron Beam Dump East ARC

North LINAC

Polarimeter

GlueX Commissioning June 4, 2016 Meson 2016 - C.A. Meyer 13

Generated: April 25, 2016

Integrated Beam Time [Days]1050 15

Num

ber o

f Eve

nts C

olle

cted

/ 10

9

0

10

20

30

TotalUnpolarized|| Polarization⊥ Polarization

Spring 2016 run with 12-GeV electrons on thin diamond radiators. Linear polarization, both perpendicular and parallel to the earth, collected.

GlueX Calorimeter Performance


Mγγ [GeV/c2]0.00 0.05 0.10 0.15 0.20 0.25 0.30

Cand

idat

es /

2 M

eV/c

2

0

50

100

150

200

250

0

50

100

150

200

250

300

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Cand

idat

es /

2 M

eV/c

2

Mγγ [GeV/c2]

Design Goal Design Goal

Forward Lead Glass Calorimeter Barrel Lead-Scintillating Fiber Calorimeter

GlueX Tracking Performance June 4, 2016 Meson 2016 - C.A. Meyer 15

Track to Wire Distance (d) [mm]0 1 2 3 4 5 6 7 8

Stra

w E

ffici

ency

0.0

0.2

0.4

0.6

0.8

1.0

d

8 mm

Central Drift Chamber (CDC)

0 1 2 3 4

140

160

180

200

220

240

260

Wire

Pos

ition

Res

olut

ion

[µm

]

Track to Wire Distance [mm]

Forward Drift Chamber (FDC)

Design Resolution for Cathodes and Wires: 200 µm

Achieved CathodeResolution: 150 µm

Posit

ion

Reso

lutio

n [µ

m]

200

400

600

800

0

Design Resolution: 150 µm

1000

Track to Wire Distance (d) [mm]0 1 2 3 4 5 6 7 8 9 10

x Coordinate [mm]-400 -200 0 200

0.82

0.86

0.90

0.94

0.983D

Rec

onst

ruct

ion

Effici

ency

400

Colors Index Chambers in the Third Package

GlueX Particle Identification June 4, 2016 Meson 2016 - C.A. Meyer 16

Track Momentum [GeV/c]0.0 0.5 1.0 1.5 2.0 2.5 3.0

β fro

m T

ime

of F

light

0.0

0.2

0.4

0.6

0.8

1.0

1

10

102

Positively Charged Particles

0.0 0.5 1.0 1.5 2.0 2.5 3.00.0

0.2

0.4

0.6

0.8

1.0

1

10

102

Track Momentum [GeV/c]

β fro

m T

ime

of F

light

Negatively Charged Particles

0 2 4 6 8 10 120.0

0.5

1.0

1.5

2.0

2.5

050100150200250300350400450

FCAL

Ene

rgy

/ Tra

ck M

omen

tum

Track Polar Angle [degrees]0.0 0.5 1.0 1.5 2.0 2.5 3.0

CDC

dE/dx

[keV

/cm

]

0

2

4

6

8

10

12

14

1

10

102

103

104

Positively Charged Particles

Track Momentum [GeV/c]

e+/e-

hadrons

p

π/K/e

pKπ

eKπ

e

Incorrect RF Bunch

Start of Physics in GlueX •  Initial reactions will be polarization transfer and beam asymmetry measurements.

• Spin-density matrix elements to understand production mechanisms.

• Opportunistic results from data exploration. • Cross section measurements. •  Identify known mesons in PWA. • Move on to the search for exotic hybrids.


�p ! (⇡0, ⌘, ⌘0)p �p ! (⇢0,!,�)p

Early Physics in GlueX •  Initial reactions will be polarization transfer and beam asymmetry measurements.

• Spin-density matrix elements to understand production mechanisms.

• Opportunistic results from data exploration. • Cross section measurements. •  Identify known mesons in PWA. • Move on to the search for exotic hybrids.


�p ! (⇡0, ⌘, ⌘0)p �p ! (⇢0,!,�)p

Deg

ree

of P

olar

izat

ion

0.0

0.2

0.4

0.6

0.8

1.0

Energy [MeV]0 2000 4000 6000 8000 10000 12000

Model Fit to Coherent Enhancement

Beam Asymmetry in ρ PhotoproductionJune 4, 2016 Meson 2016 - C.A. Meyer 19

-150 -100 -50 0 50 100 150φ [degrees]

dN/d

φ [A

rbitr

ary

Uni

ts]

-150 -100 -50 0 50 100 150

⊥ Polarization || Polarization

φ [degrees]Lab

Floor

ρ Deca

y Plane

ρ

π+

π−

Photon Beam

Polarizat

ion Planeφ

|| Polarization

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

-150 -100 -50 0 50 100 150φ [degrees]

Asym

met

ry

d�? / 1� P?⌃ cos 2� d�k / 1 + Pk⌃ cos 2�P⌃ cos 2� =

Nk �N?

Nk +N?

~40% Polarization

Large polarization transfer to the ρ

Between 100 and 1000 times the 3000 existing events from SLAC. Working with JPAC on models for analysis

Acceptance errors not included

20

π0 beam asymmetry Beam asymmetry Σ provides insight into dominant production mechanism

Understanding production mechanism critical to disentangling JPC of observed states in exotic hybrid search.

From experimental standpoint easily extended to ɣp→η where there are no previous measurements!

Exchange JPC

Mathieu et al. PRD 92, 074013

Data at different beam energies

June 4, 2016 Meson 2016 - C.A. Meyer

See Adam Szczepaniak’s talk on JPAC

21

π0 model: integration with JPAC

Similar to ρ0 model, simply calculate intensity based on JPAC provided function

Generate ɣp→π0p events and process through full detector simulation and reconstruction

Before Spring 2016 run estimated yields for 12 hours of beam; evaluated statistical precision

Actually collected >10x more data!

Simulation from JPAC Model

V. Mathieu (JPAC) PRD 92, 074013 A Donnachie PRC 93, 025203

12 hours of beam: statistical errors only Σ

June 4, 2016 Meson 2016 - C.A. Meyer

Pseudoscalar Beam Asymmetries


�p ! ⇡0p

�p ! ⌘p

Preliminary

Preliminary

⇠ P⌃⇡0cos 2�

⇠ P⌃⌘ cos 2�

From a subset of all available data. Polarization not yet determined.

Physics Opportunities June 4, 2016 Meson 2016 - C.A. Meyer 23

ρ’?

SLAC:

PRL 53, 751 (1984)

In the ρ event sample, we can look for higher-mass vector mesons. We observe an enhancement around 1.6 GeV with significantly more statistics than existed and we should be able to measure polarization observables.

m⇡+⇡� [GeV/c2]

Four photon final states June 4, 2016 Meson 2016 - C.A. Meyer 24

M(4γ) [GeV/c2]0.0 0.5 1.0 1.5 2.00

100

200

300

400

500

020406080

100120140160180200220

Cand

idat

es /

10 M

eV/c

2

0.0 0.5 1.0 1.5 2.0 2.5M(4γ) [GeV/c2]

Cand

idat

es /

10 M

eV/c

2

π0π0 Region ηπ0 Regionf2(1270)

σ/f0(980)

a0(980)

a2(1320)

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

1

10

210

310

M(γγ) for Pair 1 [GeV/c2]

M(γ

γ) fo

r Pai

r 2 [G

eV/c

2 ]

ηπ0

ηπ0

π0π0

�p ! p��

⇡0⇡0

⌘⇡0

⇡0⌘

⌘⌘

About 6% of the spring 2016 statistics from early in the run and using a very preliminary production run. Clear signals for σ, f0(980), f2(1270), a0(980) and a2(1320).

Forward Kaon Identification


Beam Axis

Bar Boxes

FocusingBox andReadout

Existing GlueX Forward Carriage

GlueX DIRCSupport Structure

Time of Flight andForward Calorimeter

•  Four of the BaBar DIRC bar boxes will be installed in front of the TOF wall.

•  This combined with the other PID systems in GlueX will allow us to fully study final states with strange quarks.

•  Strangeonium mesons and hybrids can be studied.

•  Hyperon and cascade baryons can be studied. Expected in 2018/2019

GlueX Experiments June 4, 2016 Meson 2016 - C.A. Meyer 26

GlueX—Hybrid mesons/spectroscopy PR-06-102, PR-12-002 & PR-13-003 GlueX—PrimEx-eta PR-10-011 (calorimeter plug) GlueX—Pion polarizability PR-13-008 (forward muon detector) GlueX—JEF: Rare eta decays PR14-004 (calorimeter upgrade)

A rating 340-540 PAC days A- rating 79 PAC Days A- rating 25 PAC Days Conditionally Approved

GlueX Experiments June 4, 2016 Meson 2016 - C.A. Meyer 27

GlueX—Study of ω photoproduction on nuclei. Workshop held in February 2016 https://www.jlab.org/conferences/kl2016/ GlueX—Physics opportunities with a secondary KL beam Workshop held in April 2016 https://www.jlab.org/conferences/photoproduction16/

LOI 2015 LOI 2015

Summary • GlueX is installed, commissioned and ready to start physics running in Fall 2016.

• All detector systems are near design specifications. • We are aggressively moving ahead on our first physics measurements.

• The broader program of exotic mesons is in sight. • Addition of kaon identification and five-times higher intensity is planned in 2018 to allow us to cover all parts of the GlueX exotic hybrid program.

• We have an extensive program beyond exotic hybrids and are excited to have new ideas and new collaborators.


Documents

THE EXPERIMENT - Curtis A. Meyer Home Page · YM glueball negative parity ... radiator. • Polarization parallel and perpendicular to floor. ... 240 Wire Position Resolution [µm]