• Understand how hadrons are constructed from the quarks and gluons of QCD• Understand the QCD basis for the nucleon-nucleon force• Explore the limits of our understanding of nuclear structure

– The transition from the nucleon-meson to the quark-gluon description

JLab’s Scientific Mission

We know that QCD works, but we still need to understand how.

Must address critical issues in “strong” QCD

+ What is the mechanism of confinement? Where is the Glue?+ Where does the dynamics of the q-q interaction make a transition from the strong (confinement) to the perturbative (QED-like) QCD regime?+ How does the nucleon mass, spin, shape come about from the sea of gluons & quark/anti-quarks?+ Do quarks and gluons play any direct role in Nuclear Matter?

The Jefferson Lab 12-GeV Upgrade

Jefferson Lab Today•Provides unique capabilities for ~2000 member international user community to explore and understand the structure of matter at its most fundamental level (quarks and gluons).

A C

•The SRF electron accelerator provides CW beams of unprecedented quality with a maximum beam energy of 6 GeV.

•CEBAF’s innovative design allows delivery of beam with unique properties to three experimental halls simultaneously, increasing scientific output.

•Each of the three halls offers complementary experimental capabilities and allows for large equipment installations to extend scientific reach.

B

12 GeV Upgrade

Scope of the proposed project includes doubling the accelerator beam energy, a new experimental Hall and associated beamline, and upgrades to the existing three experimental Halls.

New Hall

Enhanced capabilitiesin existing Halls

Add beam transport

Upgrade is designed to build on existing facility: all accelerator and nearly all experimental equipment have continued use

Service Buildings

Hall D

Cryo Plant

Counting House

Architect’s Rendering of Hall D Complex

North East corner of Accelerator

Overview of 12 GeV Physics Program

Hall DHall D – exploring origin of – exploring origin of confinementconfinement by by studying studying exotic mesonsexotic mesons

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

Hall CHall C – – precision determinationprecision determination of of valence valence quarkquark properties in nucleons and nuclei properties in nucleons and nuclei

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

50% of momentum carried by gluons

20% of proton spin carried by quark spin

But miserable knowledge ofespecially d-quarks at large x

and spin dependence at large x (here A1

n is shown)

Resolution: e.g., F2n tagging spectator proton from deuterium, and 3He(e,e’)

Unambiguous Resolution @ 12 GeV

A1n at 11

GeVW>1.2F2

n/F2p at 11 GeV

Charged Pion Electromagnetic Form Factor

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

To measure F(Q2) :• At low Q2 (< 0.3 (GeV/c)2): use + e scattering Rrms = 0.66 fm

• At higher Q2: use 1H(e,e’+)n

Scatter from a virtual pion in the proton and 1) extrapolate to the pion pole large uncertainty 2) use a realistic pion electroproduction model

• In asymptotic region, F 8s ƒ2 Q-2

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

Link to DIS and Elastic Form Factors

),,(~ ,~ , , txEHEH qqqq

DIS at =t=0

)(),()0,0,(~)(),()0,0,(

xqxqxH

xqxqxHq

q

Form factors (sum rules)

)(),,(~ , )(),,(~

) Dirac f.f.(),,(

,

1

1,

1

1

1

tGtxEdxtGtxHdx

tF1txHdx

qPq

qAq

q

q

) Pauli f.f.(),,(1

tF2txEdxq

q

J G = 1

1

)0,,()0,,(21

21 xExHxdxJ qqq

Quark angular momentum (Ji’s sum rule)

X. Ji, Phy.Rev.Lett.78,610(1997)

t

Eo = 11 GeV Eo = 6 GeV Eo = 4 GeV

BH

DVCSDVCS/BH comparable, allows asymmetry, cross section measurements

DVCS: Single-Spin Asymmetry in ep ep

Measures phase and amplitude directly

DVCS at 11 GeV can cleanly test correlations in nucleon structure(data shown – 2000 hours)

DVCS and Bethe-Heitler are coherent can measure amplitude AND phase

Exclusive 0 production on transverse target

2 (Im(AB*))/ T

t/4m2) - ReUT

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

The QCD Lagrangian and

Nuclear “Medium

Modifications”

Leinweber, Signal et al.

The QCD vacuum

Long-distance gluonic fluctuations

Lattice calculation demonstrates reduction of chiral condensate of QCD vacuum in presence of hadronic matter

qq

Does the quark structure of a nucleon get modified by the suppressed QCD vacuum fluctuations in a nucleus?

Observation that structure functions are altered in nuclei stunned much of the HEP community 24 years ago

~1000 papers on the topic; the best models explain the curve by change of nucleon structure, BUT more data are needed to uniquely identify the originWhat is it that alters the quark momentum in the nucleus?

Quark Structure of Nuclei: the EMC Effect

J. Ashman et al., Z. Phys. C57, 211 (1993)

J. Gomez et al., Phys. Rev. D49, 4348 (1994)

x

D

A

F

F

2

2

p

A

gg

1

1

2

2

A

D

F

F

g1(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

p

A

gLig

1

71 (polarized EMC effect)

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

g1(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

QCD and confinement

Large DistanceLow Energy

Small DistanceHigh Energy

PerturbativeQCD

StrongQCD

High EnergyScattering

GluonJets

Observed

Spectroscopy

GluonicDegrees of Freedom

Missing

Gluonic Excitations and the Origin of Confinement

Theoretical studies of QCD suggest that confinement is due to the formation of “Flux tubes” arising from the self-interaction of the glue, leading to a linear potential (and therefore a constant force)

Experimentally, we want to “pluck” the flux tube and see how it responds

š/r

ground state

transverse phonon modesHybrid mesons

Normal mesons

1 GeV mass difference

Jpc = 1-+

Color Field: Because of self interaction, confining flux tubes form between static color charges

Lattice QCD Flux tubes realized?

Rather like a “hole in the vacuum”, as also assumed in the Bag

Model, now responsible for the famous “flux

tube” of QCD.

Heavy Quarks Only!From D. Leinweber

Flux

tube

forms

between

qq

Confinement arises from flux tubes and

their excitation leads to a new

spectrum of mesons

From G. Bali

Where is the Glue?

Can JLab at 12 GeV find 1-+ Hybrids?

What Mass? Models + Lattice QCD predict M ~ 2 GeV

How Strong? Calculations predict plenty of statistics

How Wide? No reason (yet) to believe qqg wider than qqq

How Brittle? Not known whether the string is brittle or not…

12 GeV 9 GeV polarized photon beam good “acceptance” up to M ~ 2.5 GeV

Find plenty of glue in deep inelastic scattering,that has to end up in hadrons due to unitarity

_

M ~ 100-200 MeV

Will there be a flux tube to excite, or will the string break?

Regardless of the flux tube (here used as pedagogical example) there should be gluonic excitations with masses < 2 GeV

Why Photoproduction ?

A pion or kaon beam, when scattering occurs,

can have its flux tube excited

beam

Quark spins anti-aligned

Much data in hand but littleevidence for gluonic excitations

(and not expected)

q

q

befo

req

qaft

er

q

q

aft

er

q

q

befo

re

beamAlmost no data in hand

in the mass regionwhere we expect to find exotic hybrids

when flux tube is excited

Quark spins aligned

Jpc = 1-+

500

400

300

200

100

0

1.81.61.41.2

PWA fit

500

400

300

200

100

0

1.81.61.41.2

Mass (3 pions) (GeV)

events/20 MeV generated

Finding the Exotic Wave

Mass

Input: 1600 MeV

Width

Input: 170 MeV

Output: 1598 +/- 3 MeV

Output: 173 +/- 11 MeV

Double-blind M. C. exercise

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

Statistics shown here correspondto a few days of running.

X(exotic) 3

V(ector Meson) S = 1

Electron-Quark Phenomenology

C1i 2gAe gV

i

C2i 2gVe gA

i

C1u and C1d will be determined to high precision by APV and Qweak

C2u and C2d are small and poorly known: can be accessed in PV DIS

New physics such as compositeness, new gauge bosons:

Deviations in C2u and C2d might be fractionally large

A

V

V

A

Proposed JLab upgrade experiment will improve knowledge of 2C2u-C2d by more than a factor of 20

2H DIS Experiment at 11 GeVE’: 6.8 GeV ± 10% lab = 12.5o APV = 290 ppm

Ibeam = 90 µA 800 hours

(APV)=1.0 ppm

60 cm LD2 target

1 MHz DIS rate, π/e ~ 1 HMS+SHMS

xBj ~ 0.45Q2 ~ 3.5 GeV2

W2 ~ 5.23 GeV2

(2C2u-C2d)=0.01

PDG: -0.08 ± 0.24

Theory: +0.0986

Møller Parity-Violating Experiment: New Physics Reach

(example of large installation experiment with 11 GeV beam energy)

ee ~ 25 TeV

JLab Møller

ee ~ 15 TeV

LEP200

LHC

Complementary; 1-2 TeV reach

New Contact Interactions

Kurylov, Ramsey-Musolf, Su

Does Supersymmetry (SUSY) provide a candidate for dark matter?•Lightest SUSY particle (neutralino) is stable if baryon (B) and lepton (L) numbers are conserved•However, B and L need not be conserved in SUSY, leading to neutralino decay (RPV)

95% C.L.JLab 12 GeVMøller

Highlights of the 12 GeV Program

• Revolutionize Our Knowledge of Spin and Flavor Dependence of Valence PDFs

• Finalize Our Knowledge of Distribution of Charge and Current in the Nucleon

• Totally New View of Hadron (and Nuclear) Structure: GPDs Towards the quark angular momentum

• Exploration of QCD in the Nonperturbative Regime:Existence and properties of exotic

mesons • New Paradigm for Nuclear Physics: Nuclear Structure in Terms of QCD

Spin and flavor dependent EMC EffectStudy quark propagation through nuclear matter

• Precision Tests of the Standard ModelFactor 20 improvement in (2C2u-C2d)

12 GeV Upgrade: Project Schedule

(Feb ’06 CD-1 Documents)

• 2004-2005 Conceptual Design (CDR)• 2004-2008 Research and Development (R&D)• 2006 Advanced Conceptual Design (ACD)• 2007-2009 Project Engineering & Design (PED)• 2008 Long Lead Procurement• 2008-2012 Construction• 2012-2013 Pre-Ops (beam commissioning)

Critical Decision (CD) CD-1 Documents

CD-0 Mission Need 2QFY04 (Actual)

CD-1 Preliminary Baseline Range 2QFY06

CD-2A/3A Construction and Performance Baseline of Long Lead Items

4QFY06/3QFY07

CD-2B Performance Baseline 4QFY07

CD-3B Start of Construction 4QFY08

CD-4 Start of Operations 1QFY14

12 GeV Upgrade: Status• CD-0 approval March 31, 2004

• Period CD-0 to CD-1 is referred to as project “definition phase”

• DOE Review of the Science of the 12 GeV Upgrade (April 6-8, 2005)

– outstanding rating, several areas described as “discovery potential”

• DOE Independent Project Review or IPR (July 12-14, 2005)

– outstanding endorsement for CD-1 readiness from Lehman review in July

• CD-1 Approval February 14, 2006– Announcement at JLab by DOE Secretary Samuel Bodman

– 12 GeV Upgrade featured in DOE Office of Science Five Year Plan

– Completed “definition phase”

• Period CD-1 to CD-4 is referred to as project “execution phase”

12 GeV Upgrade: Status

Near Term:• June 2006 Annual Project Review

– Focus on preparations for CD-2B Performance Baseline

– CD-2B Review anticipated for mid-2007

• August 2006 JLab PAC 30

– First review of 12 GeV proposals – “commissioning experiments”

– Spokespersons make commitments to construction of equipment

– Key first step in identifying the research interests and significant

contributions of international collaborators

• October 2006 – start Project Engineering & Design (PED)

12 GeV Upgrade: The 12 GeV Upgrade, with its 1038+ luminosity, is expected to allow for a complete spin and flavor dependence of the valence quark region, both in nucleons and in nuclei.

Long-Term: Electron-Light Ion Collider (ELIC)ELIC is designed to provide a complete spin and flavor dependence of the nucleon and nuclear sea, to study the explicit role gluons play in the nucleon spin and in nuclei, and open the new research territory of “gluon GPDs”.

ELIC@JLab Physics Specifications

Flexible Center-of-mass energy between 20 and 65 GeV Ee ~ 3 GeV on Ei ~ 30 GeV up to Ee ~ 7 GeV on Ei ~ 150

GeV worked out in detail (gives Ecm up to 65 GeV)

CW Luminosity up to 8x1034 cm-2 sec-1 per Interaction Point Ion species of interest: protons, deuterons, 3He, light-medium

ions Proton and neutron Light-medium ions not necessarily polarized Up to Calcium

Longitudinal polarization of both beams in the interaction region (+Transverse polarization of ions +Spin-flip of both beams)

Ion Linac and pre-booster

IR IR

Beam Dump

Snake

CEBAF with Energy Recovery

3-7 GeV electrons 30- 150 GeV light ions

Solenoid

Ion Linac and pre-booster

IR IR

Beam Dump

Snake

CEBAF with Energy Recovery

3-7 GeV electrons 30- 150 GeV light ions

Solenoid

Ion Linac and pre-booster

IR IR

Beam Dump

Snake

CEBAF with Energy Recovery

3 -7 GeV electrons 30 -150 GeV light ions

Solenoid

Electron Injector

Electron Cooling

ELIC@JLab Layout(Derbenev, Chattopadhyay, Merminga et al.)

One accelerating & one decelerating pass through CEBAF

ELIC@JLab RealizationBecause ELIC is based on a completely new ring it is possible to optimize for spin preservation & handling and for high luminosity

Parameters have been pushed into new territory…

ß, lb, ring shape, crab crossing,…“ELIC proposes some very elegant and innovative

features worth further investigation” (U. Wienands, EIC2004 Summary)

Data from RHIC/RHIC-Spin, COMPASS, HERMES, JHF, JLab forthcoming to guide the requirements for key physics

The physics needs that drove us to this design are the importance of spin, a luminosity as high as possible, and a broad and flexible energy range for Hadron Physics

• How do quarks and gluons provide the binding and spin of the nucleons?

• What is the quark-gluon structure of mesons?

• How do quarks and gluons evolve into hadrons?

• How does nuclear binding originate from quarks and gluons?

• How do gluons behave in nuclei?

• Luminosity of up to 8x1034 cm-2

sec-1 (one-day life time)• One day 4,000 events/pb• Supports Precision Experiments

Lower value of x scales as s-1

• DIS Limit for Q2 > 1 GeV2 implies x down to 2.5 times 10-4

• Significant results for 200 events/pb for inclusive scattering

• If Q2 > 10 GeV2 required for Deep Exclusive Processes can reach x down to 2.5 times 10-3

• Typical cross sections factor 100-1,000 smaller than inclusive scattering high luminosity essential

Science Addressed by ELIC@JLab

EIC Monte Carlo Group•Antje Bruell (JLab)•Abhay Deshpande (SBU)•Rolf Ent (JLab)•Ed Kinney (Colorado)•Naomi Makins (UIUC)•Christoph Montag (BNL)•Joe Seele (Colorado)•Ernst Sichtermann (LBL)•Bernd Surrow (MIT)

+ Several “one-timers”: Harut Avakian,

Dave Gaskell,

Andy Miller, …

GRSV

ELIC projection (~10 days)

Examples: g1p,Transversity, Bjorken SR

Can determine the fundamental Bjorken Sum Rule to precision of better than 2%? (presently 10%)

EIC Monte Carlo work by Antje Bruell + Mindy Kohler

EIC Monte Carlo work by Naomi Makins

Examples: g1p

An excellent scientific case is developing for a high luminosity, polarized electron-light ion collider; will address fundamental issues in Hadron Physics:• The (spin-flavor) quark-gluon structure of the proton and neutron• How do quarks and gluons form hadrons?• The quark-gluon origin of nuclear binding

JLab design studies have led to an approach that promises luminosities as high as 8x1034 cm-2 sec-1 (one day lifetime), for electron-light ion collisions at a center-of-mass energy between 20 and 65 GeV• Evolutionary approach: 1x1033 cm-2 sec-1 1x1034 cm-2 sec-1 8x1034 cm-2 sec-1

Multi-pronged R&D Strategy to illuminate details of the design• Conceptual development (“Circulator Ring”, Crab Crossing)• Analysis/Simulations• Experiments (ER at high I@JLab/FEL, ER at 1 GeV@CEBAF, High I source)

This design, using energy recovery on the JLab site, can be integrated with a 25 GeV fixed target program for physics

ELIC@JLab – Conclusions

Backup Slides

N and N- Form Factors @ 12 GeV

6 GeV Projections 12 GeV Projections

6 GeV

GEp

GEn GM

n

GM(N-)

Separated Structure Functions @ 12 GeV

|

Rosenbluth Separations up to Q2 ~ 12 R = L/T

“DIS” (W2 > 4 GeV2) Limit

GPDs & Deeply Virtual Exclusive Processes

x

Deeply Virtual Compton Scattering (DVCS)

t

x+ x-

H(x,,t), E(x,,t), . .

hard vertices

– longitudinal momentum transfer

x – quark momentumfraction

–t – Fourier conjugateto transverse impact parameter

“handbag” mechanism

“Generalized Parton Distributions”

J G = 1

1

)0,,()0,,(21

21 xExHxdxJ qqq

Quark angular momentum (Ji’s sum rule)

X. Ji, Phy.Rev.Lett.78,610(1997)

A =

=

Measuring GPDs through polarization

LU~ sinIm{F1H + (F1+F2)H +kF2E}d~

Polarized beam, unpolarized target:

Unpolarized beam, longitudinal target:

UL~ sinIm{F1H+(F1+F2)(H +/(1+)E) -.. }d~

Unpolarized beam, transverse target:

UT~ sinIm{k(F2H – F1E) + …. }d

= xB/(2-xB)

k = t/4M2

H(,t)

Kinematically suppressed

Kinematically suppressed

H(,t), H(,t)~

Kinematically suppressed

H(,t), E(,t)

•The couplings g depend on electroweak physics as well as on the weak vector and axial-vector hadronic current •With specific choice of kinematics and targets, one can probe new physics at high energy scales•With other choices, one can probe novel aspects of hadron structure

(gAegV

T + gV

egAT)

PV AsymmetriesWeak Neutral Current (WNC) Interactions at Q2 << MZ

2

Longitudinally Polarized Electron Scattering off Unpolarized Fixed Targets

12 GeV TechnologyEvolutionary upgrade in machine and experimental equipment:

– cryomodule technology advancements• allow for nearly 100% increase in acceleration using only 25%

additional space via higher gradient and increased effective accelerating length– Original CEBAF: 20 MV achieved– Present CEBAF average: 28 MV (max=34MV) achieved– SL21 (first prototype) 70 MV achieved– FEL3 (second prototype) 80 MV achieved– Renascence (final prototype) 98 MV (12 GeV requirement)

testing underway

– demonstrated detector technology for upgraded equipment• much Hall D detector technology well-developed by GlueX collaboration

• Hall C SHMS detectors are copies of existing HMS detectors

• most Hall B and Hall C magnet designs close to existing designs

New Capabilities in Halls A, B & C, and New Hall D

9 GeV tagged polarized photons and a 4 hermetic detector

D

Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles

C

CLAS upgraded to higher (1035) luminosity and coverage

B

High Resolution Spectrometer (HRS) Pair, and specialized large installation experiments

A

7 GeVelectron

150 GeV proton

One-event display from EIC Monte Carlo

An Electron Ion Collider will allow us to look in detail into the sea of quarks and gluons, to create and study gluons, and to discover how energy transforms into matter From DOE 20-year plan

The same electron accelerator can also provide 25 GeV electrons for fixed target experiments for

physics

Implement 5-pass recirculator, at 5 GeV/pass, as in present CEBAF

Exploring whether collider and fixed target modes can run simultaneously (can in alternating mode)

(straightforward upgrade, no accelerator R&D needed)

Luminosity of 1038+ Complementary capabilities for broad class of experiments

Towards Higher Electron Beam Current

ELIC with circulator ring

JLab FEL program with unpolarized

beam

Year

Ave

. Bea

m C

urre

nt (

mA

)

First polarized beam from GaAs photogun

First low polarization, then

high polarization at CEBAF

Source requirements for ELIC less demanding with circulator ring! Few mA’s versus >> 100 mA of highly polarized beam.

@highestluminosity

CEBAF enjoys excellent gun lifetime:~200 C charge lifetime (until QE reaches 1/e of initial value) ~100,000 C/cm2 charge density lifetime (we use a ~0.5 mm dia. spot)

If Charge-Lifetime assumption valid: With ~1 cm dia. spot size lifetime of 36 weeks at 25 mA!

Lifetime Estimate @ 25 mA:

Need to test the scalability of charge lifetime with laser spot diameter Measure charge lifetime versus laser spot diameter in lab. (Poelker, Grames)

ERL Technology demonstrated at CEBAF @ 1 ERL Technology demonstrated at CEBAF @ 1 GeVGeV

50 MeV

500 MeV

500 MeV

1 GeV1 GeV

500 MeV500 MeV

50 MeV

Special installation of a RF/2 path length delay chicane, dump and beamline diagnostics.

~1 GeV Accelerating beam

~55 MeV Decelerating beam

RF Response to Energy RF Response to Energy RecoveryRecovery

0.20

0.15

0.10

0.05

0.00

-0.05

-0.10

-0.15

Vol

ts

350300250200150100500Time(s)

• Gradient modulator drive signals with and without energy recovery in response to 250 sec beam pulse entering the RF cavity (SL20 Cavity 8)

250 s

with ERwithout ER

Gluon Spin in the Nucleon

s1

2

1

2 Lq G LG

0.250.1Gluon contribution is likely to be substantial: Profound implications for our basic understanding of the nucleon which must be directly measured by experiment

The gold standard: measure G from a variety of experiments, where the dominant theoretical input is NLO QCD and residual model dependence is negligible and non-controversial

The dream is to produce a similar plot for xg(x) vs x

HERA

G/G from open charm: similar precision as RHIC-SPIN extended down to x = 0.001