The JLab 12 GeV UpgradeThe JLab 12 GeV Upgrade

• Upgrade of accelerator and experimental equipment

• Highlights of the physics program @ 12 GeV

• Highlights of spin dependent measurements @ 12 GeV

• Timelines and schedule

Antje Bruell, JLabPacSpin 2007, Vancouver, Canada

Jefferson Lab Today2000 member international user community engaged in exploring quark-gluon structure of matter

A C

Superconducting accelerator provides 100% duty factor beams of unprecedented quality, with energies up to 6 GeV

CEBAF’s innovative design allows delivery of beam with unique properties to three experimental halls simultaneously

Each of the three halls offers complementary experimental capabilities and allows for large equipment

installations to extend scientific reach

B

A B C

Jefferson Lab Today

Two high-resolution 4 GeV spectrometers Large acceptance spectrometer

electron/photon beams

7 GeV spectrometer, 1.8 GeV spectrometer,

large installation experiments

Hall A Hall B

Hall C

6 GeV CEBAF1112

CHL-2CHL-2

Upgrade magnets Upgrade magnets and power and power suppliessupplies

Enhanced capabilities in existing Halls

Lower pass beam energies still available

Hall DHall D – – exploring origin ofexploring origin of confinementconfinement by studyingby studying exotic exotic

mesonsmesons

Hall BHall B – understanding – understanding nucleon structurenucleon structure via via generalized parton distributionsgeneralized parton distributions

Hall CHall C – precision determination of – precision determination of valence quarkvalence quark properties in nucleons and properties in nucleons and

nucleinuclei

Hall AHall A – short range correlations, form – short range correlations, form factors, hyper-nuclear physics, futurefactors, hyper-nuclear physics, future new new experimentsexperiments

Experimental equipment for 12 Experimental equipment for 12 GeVGeV

Technical Performance RequirementsTechnical Performance Requirements

Hall D Hall B Hall C Hall A

excellent hermeticity

luminosity

10 x 1034

energy reach installation space

polarized photons

hermeticity precision

EGeV 11 GeV beamline

108 photons/s target flexibility

good momentum/angle resolution

excellent momentum resolution

high multiplicity reconstruction luminosity up to 1038

particle ID

Experimental Systems

Remainder of 12GeV Upgrade

TEC58.8%

Construction38.2%

PED3.1%

Physics Experimental Equipment Physics Experimental Equipment

Physics TEC by Sub SystemHall A1.2%

Hall B33.3%

Hall C26.8%

Hall D38.8%

total project cost: $ 310 M

QCD and confinementQCD and confinement

Large DistanceLow Energy

Small DistanceHigh Energy

Perturbative QCD Strong QCD

High Energy Scattering

GluonJets

Observed

Spectroscopy

GluonicDegrees of Freedom

Missing

Gluonic ExcitationsGluonic Excitations

Flux

tube

forms

between

qq

From G. Bali

• predicted by QCD• crucial for understanding confinement• quantum numbers of the excited gluonic fields couple to those of the quarks to produce mesons with exotic quantum numbers• mass spectra calculated by lattice QCD

possibility for experimental search

Gluonic Excitations

s/r

ground state

transverse phonon modesHybrid mesons

Normal mesons

1 GeV mass difference

Hybrid mesons and mass predictions

Jpc = 1-+

q

q

q

q

Lattice 1-+ 1.9 GeV2+- 2.1 GeV0+- 2.3 GeV

Lowest mass expected to be 1(1−+) at 1.9±0.2 GeV

GlueX / Hall D DetectorGlueX / Hall D Detector

Electron Beam from CEBAF

Lead GlassDetector

Solenoid

Coherent BremsstrahlungPhoton Beam

Tracking

TargetCerenkovCounter

Time ofFlight

BarrelCalorimeter

Note that tagger is80 m upstream of

detector

12 GeV electrons

collimated

500

400

300

200

100

0

1.81.61.41.2

PWA fit

Output: 1598 +/- 3 MeV

Output: 173 +/- 11 MeV

Double-blind M. C. exercise

Statistics shown here correspondto a few days of running.

500

400

300

200

100

0

1.81.61.41.2

Mass (3 pions) (GeV)

events/20 MeV generated

Mass

Input: 1600 MeV

Width

Input: 170 MeV

Finding an Exotic WaveFinding an Exotic Wave

An exotic wave (JPC = 1-+) was generated at level of 2.5 % with 7 other waves. Events were smeared, accepted, passed to PWA fitter.

X(exotic)→ ρπ→ 3π

Neutron/Proton Charge Form Factor @12 GeVNeutron/Proton Charge Form Factor @12 GeV

(Polarization Experiments only)

Here shown as ratio of Pauli & Dirac Form Factors F2 and F1,ln2(Q2/2)Q2F2/F1 constant when taking orbital angular momentum into account (Ji)

Charged Pion Electromagnetic Form FactorCharged Pion Electromagnetic Form Factor

applicability of pQCD (GPD’s) to exclusive pion production ?

Where does the dynamics of the q-q interaction make a transition from the strong (confinement) to the perturbative (QED-like) QCD regime?

• It will occur earliest in the simplest systems the pion form factor F(Q2) provides our best chance to determine the relevant distance scale experimentally

with enough luminosity to reach the high-Qwith enough luminosity to reach the high-Q22, high-x region!, high-x region!

Counts/hour/ (100 MeV)2 (100 MeV2) for L=1035 cm-2 sec-1

Access to the DIS Regime @ 12 GeVAccess to the DIS Regime @ 12 GeV

Extending DIS to High xExtending DIS to High x

12 GeV will access the valence quark regime (x > 0.3)

The Neutron Asymmetry A1

(similar precision for p and d)

The Neutron to Proton Structure Function Ratio

CLAS: tagging spectator proton

Hall C: 3H/3He

3He(e,e’)

Ee =11 GeV NH3+He3

Flavor decomposition using SIDISFlavor decomposition using SIDIS

Valence quarks

Large flavor asymmetry in

unpolarized sea

Asymmetry in polarized sea?

First data from HERMES compatible with zero but have large uncertainties

Calculations:– Instantons (QSM)

– Pion cloud models ?

Flavor decomposition: polarized seaFlavor decomposition: polarized sea

(Goeke)

More data expected from RHIC SSA in future

Beyond form factors and quark distributions – Generalized Parton Distributions (GPDs)

Proton form factors, transverse charge & current densities

Structure functions,quark longitudinalmomentum & helicity distributions

X. Ji, D. Mueller, A. Radyushkin (1994-1997)

Correlated quark momentum and helicity distributions in transverse space - GPDs

Kinematics for deeply excl. experimentsKinematics for deeply excl. experimentsno overlap with otherexisting experiments

compete with other experiments

Q2 = 5.4 GeV2 x = 0.35-t = 0.3 GeV2

CLAS experiment E0 = 11 GeV Pe = 80% L = 1035 cm-2s-1

Run time: 2000 hrs

DVCS Single-Spin AsymmetryDVCS Single-Spin AsymmetryDVCS: Single Spin Asymmetry

Many x, Q2 and t values measured simultanously !

Projected results

Spatial Image

Projected precision in extraction of GPD H at x =

orbital angular momentum carried by quarks : solving the spin puzzle

Ingredients:1) GPD Modeling2) HERMES 1H(e,e’)p (transverse target spin asymmetry)

3) Hall A 2H(e,e’n)p

Compared to Lattice QCD

At one value of x only

k

k'

* q q'

p p'

e

For quarks 12 GeV will give final answers

Exclusive 0 production on transverse target

2 (Im(AB*))/ T

|A|2(1-2) - |B|2(2+t/4m2) - Re(AB*)22AUT = -

Asymmetry depends linearlyon the GPD E, which enters Ji’s sum rule.

A ~ 2Hu + Hd

B ~ 2Eu + Ed0

K. Goeke, M.V. Polyakov,M. Vanderhaeghen, 2001

A ~ Hu - Hd

B ~ Eu - Ed+

AUT

xB

0

Longitudinally polarized Target Longitudinally polarized Target SSA for SSA for ++

Measurement of kT dependent twist-2

distribution provides an independent test of the Collins fragmentation.

Efremov et al.

•Study the PT – dependence of AULsin2

•Study the possible effect of large unfavored Collins function.

Real part of interfe-rence of wave functions with L=0 and L=1

quarkkT

In noncollinear single-hadron fragmentation additional FF H1(z,kT) )(hq

1 zH →⊥

Transverse Target SSA @11 GeVTransverse Target SSA @11 GeV

AUT ~Collins

AUT ~Sivers

Simultaneous (with pion SIDIS) measurement of, exclusive with a transversely polarized target important to control the background.

CLAS @ 11GeV (NH3)

0

-

+

f1T┴, requires final state interactions + interference between different helicity states

Transversity in double pion production

Dihadron production provides an alternative, “background free” access to transversity

h1

h2

quark

RT

“Collinear” dihadron fragmentation described by two functions at leading twist:

D1(z,cosR,M),H1R(z,cosR,M)

...Hh)sin(A RSRUT ++∞ ⊥

11

The angular distribution of two hadrons is sensitive to the spin

of the quark

relative transverse momentum of the two hadrons replaces the PT in single-pion production (No transverse momentum of the pair center of mass involved )

Collins et al, Ji, Jaffe et al, Radici et al.

Observation that structure functions are altered in nuclei stunned much of the HEP community 23 years ago

~1000 papers on the topic; BUT more data are needed to uniquely identify the origin: What alters the quark momentum in the nucleus?

Quark Structure of Nuclei: Origin of the Quark Structure of Nuclei: Origin of the EMC EffectEMC Effect

x

JLab 12

D

A

F

F

2

2

Jlab at 12 GeV• Precision study of A-dependence• Measurements at x>1 • “Polarized EMC effect”• Flavor-tagged (polarized) structure functions• valence vs. sea contributions

( )p

A

gLig

1

71 (polarized EMC effect)

Curve follows calculation by W. Bentz, I. Cloet, A. W. Thomas.

gg11(A) – “Polarized EMC Effect”(A) – “Polarized EMC Effect”

New calculations indicate larger effect for polarized structure function than for unpolarized: scalar field modifies lower components of Dirac wave function

Spin-dependent parton distribution functions for nuclei nearly unknown

Can take advantage of modern technology for polarized solid targets to perform systematic studies – Dynamic Nuclear Polarization

““Polarized EMC Effect” – Flavor TaggingPolarized EMC Effect” – Flavor Tagging

semi-inclusive DIS on polarized targets, measuring + and -, decompose to extract uA(x), dA(x).

Challenging measurement, but have new tools:

– High polarization for a wide variety of targets

– Large acceptance to constrain syst. errors and tune models

uA(x)

u(x)

x

uv(x)

free nucleon+ scalar field+ Fermi+ vector field(total)

dv(x)

W. Bentz, I. Cloet, A. W. Thomas

Rat

ios

dA(x)

d(x)

nuclear matter nuclear matter

AAPVPV Measurements Measurements

APV ~ 8 x 10-5 Q2 0.1 to 100 ppm

• Steady progress in technology• part per billion systematic control• 1% normalization control• JLab now takes the lead

-New results from HAPPEX-Photocathodes-Polarimetry-Targets-Diagnostics-Counting Electronics

E-05-007

DOE Generic Project TimelineDOE Generic Project Timeline

We are hereDOE CD-2 Reviews

September 2007

2004-2005 Conceptual Design (CDR) - finished

2004-2008 Research and Development (R&D) - ongoing

2006 Advanced Conceptual Design (ACD) - finished

2006-2008 Project Engineering & Design (PED) - ongoing

2009-2013 Construction – starts in ~18 months!

Accelerator shutdown start mid 2012

Accelerator commissioning mid 2013

2013-2015 Pre-Ops (beam commissioning)

Hall commissioning start late 2013

(based on funding guidance provided by DOE-NP in April 2007)

12 GeV Upgrade: Phases and 12 GeV Upgrade: Phases and ScheduleSchedule

Summary

The Jlab 12 GeV Upgrade will increase the energy of CEBAF, provide very high luminosities and will thus allow to measure with unprecedented precision:

• the high x behaviour of (un)polarised structure functions• the spin and flavour decomposition in the valence region • pion and nucleon form factors at high Q2

• single spin asymmetries and kt dependent effects • deep exclusive processes in multi-differential form • nuclear effects in (semi)-inclusive scattering• search for hybrid states• parity violating asymmetries as a test of the standard model

The ideal laboratory for valence quark physics !

Quantum Numbers of Hybrid MesonsQuantum Numbers of Hybrid MesonsQuarks

Excited Flux Tube Hybrid Meson⊕

S=0

L =0

J PC =0−+

J PC =1+−

1−+

⎧ ⎨ ⎪

⎩ ⎪ J PC =

1−−

1++

⎧ ⎨ ⎪

⎩ ⎪

π, Klike

J PC =0−+ 1−+ 2−+

0+− 1+− 2+−

⎧ ⎨ ⎪

⎩ ⎪

S=1

L =0

J PC =1−−

J PC =1+−

1−+

⎧ ⎨ ⎪

⎩ ⎪

like γ,ρ

Exotic

Flux tube excitation (and parallel quark spins) lead to exotic JPC

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 MapMeson Map

Lattice 1-+ 1.9 GeV2+- 2.1 GeV0+- 2.3 GeV

Unraveling the Quark WNC CouplingsUnraveling the Quark WNC Couplings

12 GeV:(2C2u-C2d)=0.01

PDG: -0.08 ± 0.24

Theory: +0.0986

€

C1i ≡ 2gAe gV

i

€

C2i ≡ 2gVe gA

i

A

V

V

A

Vector quark couplings Axial-vector quark couplings