The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status

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The 12 GeV Upgrade of Jefferson Lab Physics
Program and Project Status

• Will Brooks
• Jefferson Lab

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Jefferson Lab Today

• 2000 member international user community engaged
  in exploring quark-gluon structure of matter

Superconducting accelerator provides 100 duty
factor beams of unprecedented quality, with
energies up to 6 GeV.
C
B
A
CEBAFs 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.
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Jefferson Lab Today
Hall B
Hall A
Two high-resolution 4 GeV spectrometers
Large acceptance spectrometer electron/photon
beams
Hall C
7 GeV spectrometer, 1.8 GeV spectrometer, large
installation experiments
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Jefferson Lab Tomorrow

• Double the beam energy to 12 GeV
• New large acceptance spectrometer for photon-beam
  physics (D)
• New focusing spectrometer for highest energies
  (C)
• Ten-fold increase in luminosity for
  large-acceptance electron beam experiments (B)

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New Capabilities in Halls A, B, C, and a New
Hall D
D
C
9 GeV tagged polarized photons and a 4? hermetic
detector
Super High Momentum Spectrometer (SHMS) at high
luminosity and forward angles
B
A
CLAS upgraded to higher luminosity (1035 /cm2-s)
High Resolution Spectrometer (HRS) Pair, and
specialized large installation experiments
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Highlights of the12 GeV Science Program
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Highlights of the 12 GeV Science Program

• Unlocking the secrets of QCD confinement and
  space-time dynamics
• New and revolutionary access to the structure of
  the proton and neutron
• Discovering the quark structure of nuclei
• Precision tests of the Standard Model

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Unlocking the secrets of QCD confinement and
space-time dynamics
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The search for exotic mesons GlueX in Hall D

• Excitation of the gluonic field binding the
  quarks in a meson is an expected consequence of
  the non-Abelian nature of QCD
• An experimental manifestation of such an
  excitation is exotic quantum numbers
• The focus of the GlueX experiment in Hall D is to
  identify and study exotic mesons, and to infer
  features of confinement from the observed spectrum

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• Lattice QCD studies confirm flux tube formation
  for quenched static quarks
• Resulting effective potential is approximately
  linear with positive slope
• Light quarks may be more complicated but
  qualitative features are expected to remain,
  resulting in an excitation spectrum

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• Exotics expected in a mass range well-matched to
  GlueX detector and 12 GeV electron beam
• Linearly polarized photons of 9 GeV give access
  to this mass range and offer several advantages
  relative to pion beam searches
• Mapping out the full nonet of exotic mesons is
  planned
• Extensive parallel effort in Lattice QCD is
  underway

Experiment optimized for high sensitivity to
exotics
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Quark Propagation and Hadron FormationQCD
Confinement in Forming Systems

• How long can a light quark remain deconfined?
• The production time tp measures this
• Deconfined quarks emit gluons
• Measure tp via medium-stimulated gluon emission
• How long does it take to form the color field of
  a hadron?
• The formation time tfh measures this
• Hadrons interact strongly with nuclear medium
• Measure tfh via hadron attenuation in nuclei

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How long can a light quark remain deconfined?

• Ubiquitous sketch of hadronization process
  string/color flux tube

Dominant mechanism not known from experiment
Kopeliovich, Nemchik, Predazzi, Hayashigaki,
Nuclear Physics A 740 (2004) 211245
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• Two distinct dynamical stages, each with
  characteristic time scale

Formation time tfh
Time required to form color field of
hadron Signaled by interactions with known hadron
cross sections No gluon emission (Hadron
attenuation)
Production time tp
Time during which quark is deconfined Signaled by
medium-stimulated energy loss via gluon
emission (pT broading)
These time scales are essentially unknown
experimentally
Accardi, Grünewald, Muccifora, Pirner, Nuclear
Physics A 761 (2005) 6791
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Experimental Approach

• Direct measurements of time intervals at
  femptometer distance scales are feasible using
  nuclei as spatial analyzers
• The well-understood properties of nuclei
  (densities, currents) make a reliable analysis
  feasible
• With an assortment of nuclei of varying size, a
  systematic study can be performed

• Two observables
• pT broadening
• Hadronic multiplicity ratio

Airapetian, et al. (HERMES) PRL 96, 162301 (2006)
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Production length from JLab/CLAS 5 GeV data
(Kopeliovich, Nemchik, Schmidt, hep-ph/0608044)
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Accessible Hadrons (12 GeV) Formation length
extraction
For more on this, see talk by W. B. on Friday
morning
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Color transparency in r electroproduction

• Color Transparency is a spectacular prediction of
  QCD under the right conditions, nuclear matter
  will allow the transmission of hadrons with
  reduced attenuation
• Totally unexpected in an hadronic picture of
  strongly interacting matter, but straightforward
  in quark gluon basis
• Why rho? Should be evident first in mesons

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• The signature of CT is the rising of the nuclear
  transparency TA with increasing hardness of the
  reaction (Q)

• Measurement at fixed coherence length needed for
  unambiguous interpretation

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• Predicted results high-precision, will permit
  systematic studies

For more on this, see talk by K. Hafidi on Friday
morning
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New and revolutionary access to the structure of
the proton and neutron
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Valence d-quark distributions poorly known
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Valence structure function flavor dependence
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Valence spin structure
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Important complement to RHIC Spin data
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Proton electric form factor
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Neutron Magnetic Form Factor
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Generalized Parton Distributions
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GPDs via cross sections and asymmetries
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New, comprehensive view of hadronic structure
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Deeply Virtual Exclusive Processes - Kinematics
Coverage of the 12 GeV Upgrade
JLab Upgrade
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The quark structure of nuclei
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The 12 GeV Program for the Physics of Nuclei

• Quark propagation through nuclei
• Color transparency
• GPDs of nuclei
• Universal scaling behavior
• Threshold J/Y photoproduction on nuclei
• Short-range correlations and cold dense matter
• Few-body form factors

• The quark structure of nuclei

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Nucleons and Pions or Quarks and Gluons?

• From a field theoretic perspective, nuclei are a
  separate solution of QCD Lagrangian
• Not a simple convolution of free nucleon
  structure with Fermi motion
• Point nucleons moving non-relativistically in a
  mean field describes lowest energy states of
  light nuclei very well
• But description must fail at small distances
• In nuclear deep-inelastic scattering, we look
  directly at the quark structure of nuclei
• This is new science, and largely unexplored
  territory
• New experimental capabilities to attack
  long-standing physics issues

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The QCD Lagrangian and Nuclear Medium
Modifications
The QCD vacuum
Long-distance gluonic fluctuations

Leinweber, Signal et al.
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Does the quark structure of a nucleon get
modified by the suppressed QCD vacuum
fluctuations in a nucleus?
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Quark Structure of Nuclei Origin
of the EMC Effect

• Observation that structure functions are altered
  in nuclei stunned much of the HEP community 23
  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
  origin
• What is it that alters the quark momentum in the
  nucleus?

J. Ashman et al., Z. Phys. C57, 211 (1993) J.
Gomez et al., Phys. Rev. D49, 4348 (1994)
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Unpacking the EMC effect

• With 12 GeV, we have a variety of tools to
  unravel the EMC effect
• Parton model ideas are valid over fairly wide
  kinematic range
• High luminosity
• High polarization
• New experiments, including several major
  programs
• Precision study of A-dependence xgt1 valence
  vs. sea
• g1A(x) Polarized EMC effect influence of
  nucleus on spin
• Flavor-tagged polarized structure functions
  DuA(xA) and DdA(xA)
• x dependence of axial-vector current in nuclei
  (can study via parity violation)
• Nucleon-tagged structure functions from 2H and
  3He with recoil detector
• Study x-dependence of exclusive channels on
  light nuclei, sum up to EMC

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EMC Effect - Theoretical Explanations

• Quark picture
• Multi-quark cluster models
• Nucleus contains multinucleon clusters (e.g.,
  6-quark bag)
• Dynamical rescaling
• Confinement radius larger due to proximity to
  other nucleons

• Hadron picture
• Nuclear binding
• Effects due to Fermi motion and nuclear binding
  energy, including virtual pion exchange
• Short range correlations
• High momentum components in nucleon wave function

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What is the role of binding energy in the EMC
effect? What is the role of Fermi momentum (at
high x)? Are virtual pions important?
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EMC Effect in 3He and 4He

• Current data do not differentiate between
  A-dependence or r-dependence.
• Can do exact few-body calculations, and
  high-precision measurement
• Fill in high-x region transition from
  rescaling to Fermi motion?

Hermes data
SLAC fit to heavy nuclei (scaled to 3He)
Calculations by Pandharipande and Benhar for 3He
and 4He
Approximate uncertainties for 12 GeV coverage
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Do multi-quark clusters exist in the nuclear
wavefunction? Do they contribute significantly
to the EMC effect?
How to answer tag overlapping nucleons
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Multi-quark clusters are accessible at large x
(gtgt1) and high Q2
12 GeV gives access to the high-x, high-Q2
kinematics needed to find multi-quark clusters
Fe(e,e) 5 PAC days
Mean field
Six-quark bag (4.5 of wave function)
Correlated nucleon pair
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Is the EMC effect a valence quark phenomenon, or
are sea quarks also involved?
Incident quark, x1
Target anti-quark, x2
m
m-
Drell-Yan data from Fermilab, showing no clear
excess of anti-quarks in nuclei
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Flavor-tagged EMC Effect

• Sea and valence expected to be quite different
• Detect p, p-, (K, K-), do flavor decomposition
  

• Global fit of electron and muon DIS experiments
  and Drell-Yan data

x
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What is the role of relativity in the description
of the EMC effect? What can be learned from spin?
Surprises 23 years ago EMC effect 17 years
ago the spin crisis will there be another
spin crisis in nuclei?

• Quantum field theory for nuclei
• Large (300-400 MeV) Lorentz scalar and vector
  fields required
• Binding energies arise from cancellations of
  these large fields
• Relativity an essential component
• Quark-Meson Coupling model
• Lower Dirac component of confined light quark
  modified most by the scalar field
• How to probe the lower component further? SPIN!

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g1A(x) Polarized EMC Effect

• Spin-dependent parton distribution functions for
  nuclei essentially unknown
• Can take advantage of modern technology for
  polarized solid targets to perform systematic
  studies Dynamic Nuclear Polarization
• Correct relativistic description will also help
  to explain ordinary EMC effect

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g1(A) Polarized EMC Effect Some Solid
Target Possibilities
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Polarized EMC Effect
Assumes 11 GeV beam, 40 target polarization, 80
beam polarization and running for 70 days study
by Vipuli Dharmawardane
Systematic error target is lt 5
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Can we go further in understanding relativistic
effects and the role of quark flavor? How much
of the spin is carried by the valence quarks? Is
there a nuclear spin crisis too?
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Polarized EMC Effect Flavor Tagging

• Can perform semi-inclusive DIS on sequence of
  polarized targets, measuring p and p-, decompose
  to extract DuA(xA), DdA(xA).
• Challenging measurement, but have new tools
• High polarization for a wide variety of targets
• Large acceptance detectors to constrain
  systematic errors and tune models

Ratios
nuclear matter
nuclear matter
W. Bentz, I. Cloet, A. W. Thomas
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Precision Tests of the Standard Model
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Electron-Quark Phenomenology
V
A
A
V
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
Proposed JLab upgrade experiment will improve
knowledge of 2C2u-C2d by more than a factor of 20
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Parity Violating Electron DIS
e-
e-
?
Z
X
N
fi(x) are quark distribution functions
For an isoscalar target like 2H, structure
functions largely cancels in the ratio
Provided Q2 and W2 are high enough and x 0.3
Must measure APV to fractional accuracy better
than 1

• 11 GeV at high luminosity makes very high
  precision feasible
• JLab is uniquely capable of providing beam of
  extraordinary stability
• Control of systematics being developed at 6 GeV

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2H Experiment at 11 GeV
APV 290 ppm
E 6.8 GeV 10
?lab 12.5o
800 hours
60 cm LD2 target
Ibeam 90 µA
xBj 0.45 Q2 3.5 GeV2 W2 5.23 GeV2
1 MHz DIS rate, p/e 1 HMSSHMS
?(APV)1.0 ppm
?(2C2u-C2d)0.01
PDG -0.08 0.24
Theory 0.0986
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The 12 GeV Upgrade Project Status and Schedule
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DOE Generic Project Timeline
We are here
DOE Reviews
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12 GeV Upgrade Phases and Schedule

• (based on funding profile provided April 2006)

• 2004-2005 Conceptual Design (CDR) - finished
• 2004-2008 Research and Development (RD) -
  ongoing
• 2006 Advanced Conceptual Design (ACD) - finished
• 2006-2009 Project Engineering Design (PED) -
  starting
• 2009-2013 Construction starts in less than two
  years!
• Accelerator shutdown start early 2012
• Accelerator commissioning late 2012 - early 2013
• 2013-2014 Pre-Ops (beam commissioning)
• Hall commissioning start early-mid 2013

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12 GeV Upgrade Recent News

• June - DOE Annual Review of Project Progress
• High marks for progress and planning
• July 35 Design and Safety Review for Hall D
  Complex Civil Construction, plus completed a
  value engineering study
• August - JLab PAC 30
• First review of 12 GeV proposals commissioning
  experiments
• Key first step in identifying the research
  interests and significant contributions of
  international and other non-DOE collaborators
• September Two Internal Project Reviews 1)
  Cryomodules and 2) new Superconducting Magnets
• October Start of FY07, 7M of PED funds now
  flowing AE firm authorized to proceed with 60
  design of Hall D Complex project design phase
  now in full swing!

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12 GeV Physics Plans for FY07

• Detailed plans for FY07 RD and PED have been
  cast into a resource-loaded schedule
• 250 activities and milestones
• Approximately 25 paid FTEs matrixed from 50
  laboratory staff
• Additional 17 FTEs of contributed university
  labor
• Incorporates ESHQ activities and milestones
• Major RD goals include
• Prototyping of 8 detector systems
• Three studies focusing on superconducting magnets
• Six studies on electronics, detector, or
  shielding issues
• Major PED efforts include
• Reference designs for 7 superconducting magnets
  Tagger system
• Designs for 12 major detector systems
• Designs for electronics and infrastructure
  components

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FY07 DOE Reviews

• Early January (tentative) Project Status
  Review
• 4-person review committee, led by JSO
• Focus Resource-loaded schedule, extensive
  documentation
• Late January Mini-Review
• Lehman/DOE-NP review, small group
• Early Summer Baseline Readiness Review, stage I
• Conducted by Lehman office (IPR). Major review.
• Mid-Summer Baseline Readiness Review, stage II
• Conducted by OECM (EIR). Major review.

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Conclusions

• Exciting science program!
• Amazingly broad and diverse
• Earthshaking impacts
• Project is now in intensive design phase
• Construction phase less than 2 years away
• Goal is to bring all systems to readiness for
  baseline in 6 months
• We are on track for accomplishing this!

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• BACKUP TRANSPARENCIES

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Reminder semi-inclusive DIS
Detect a final state hadron in addition to
scattered electron
Can tag the flavor of the struck quark by
measuring the hadrons produced flavor tagging
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g1(A) Polarized EMC Effect 7Li as Target

• Shell model 1 unpaired proton, 2 paired neutrons
  in P3/2, closed S1/2 shell.
• Cluster model triton alpha
• 7Li polarization 90
• Nucleon polarization calculations
• Cluster model 57
• GFMC 59
• 59 x 90 53
• Proton embedded in 7Li with over
  50 polarization!