the 12 gev upgrade of jefferson lab: physics program and project status will brooks jefferson lab
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The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status
Will Brooks
Jefferson Lab
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
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)
New Hall
Enhanced capabilitiesin existing Halls
New Capabilities in Halls A, B, & C, and a 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 luminosity (1035 /cm2-s)
B
High Resolution Spectrometer (HRS) Pair, and specialized large installation experiments
A
Highlights of the12 GeV Science Program
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
Unlocking the secrets of QCD: confinement and space-time dynamics
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
• 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
• 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
Quark Propagation and Hadron Formation:QCD Confinement in Forming Systems
• How long can a light quark remain deconfined? – The production time p measures this
– Deconfined quarks emit gluons
– Measure p via medium-stimulated gluon emission
• How long does it take to form the color field of a hadron?– The formation time f
h measures this
– Hadrons interact strongly with nuclear medium
– Measure fh via hadron attenuation in nuclei
How long can a light quark remain deconfined?
• Ubiquitous sketch of hadronization process: string/color flux tube
RG
GY
Dominant mechanism not known from experiment
Kopeliovich, Nemchik, Predazzi, Hayashigaki, Nuclear Physics A 740 (2004) 211–245
• Two distinct dynamical stages, each with characteristic time scale:
Formation time tfh
Production time tp
Time during which quark is deconfinedSignaled by medium-stimulated energy loss via gluon emission:
(pT broading)
Time required to form color field of hadron
Signaled by interactions withknown hadron cross sections
No gluon emission(Hadron attenuation)
These time scales are essentially unknown experimentally
Accardi, Grünewald, Muccifora, Pirner, Nuclear Physics A 761 (2005) 67–91
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
Airapetian, et al. (HERMES) PRL 96, 162301 (2006)
Two observables:
1. pT broadening
2. Hadronic multiplicity ratio
Production length from JLab/CLAS 5 GeV data (Kopeliovich, Nemchik, Schmidt, hep-ph/0608044)
Acc
ess
ible
Hadro
ns
(12
GeV
) Fo
rmati
on length
extr
act
ion
For more on this, see talk by W. B. on Friday morning
Color transparency in 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
• 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
)(
222 QMV
c
• Predicted results high-precision, will permit systematic studies
For more on this, see talk by K. Hafidi on Friday morning
New and revolutionary access to the structure of the proton and neutron
Valence d-quark distributions poorly known
Valence structure function flavor dependence
Valence spin structure
p1A
Important complement to RHIC Spin data
Proton electric form factor
Neutron Magnetic Form Factor
Generalized Parton Distributions
GPDs via cross sections and asymmetries
New, comprehensive view of hadronic structure
Deeply Virtual Exclusive Processes - Kinematics Coverage of the 12 GeV Upgrade
JLab Upgrade
Upgraded JLab hascomplementary& unique capabilities
unique to JLaboverlap with other experiments
High xB only reachablewith high luminosity H1, ZEUS
The quark structure of nuclei
The 12 GeV Program for the Physics of Nuclei
• Quark propagation through nuclei
• Color transparency
• GPDs of nuclei
• Universal scaling behavior
• Threshold J/ photoproduction on nuclei
• Short-range correlations and cold dense matter
• Few-body form factors
• The quark structure of nuclei
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
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
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 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?
Quark Structure of Nuclei: Origin of the EMC Effect
J. Ashman et al., Z. Phys. C57, 211 (1993)
J. Gomez et al., Phys. Rev. D49, 4348 (1994)
x
JLab 12
D
A
F
F
2
2
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; x>1; valence vs. sea
– g1A(x) “Polarized EMC effect” – influence of nucleus on spin
– Flavor-tagged polarized structure functions uA(xA) and dA(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
EMC Effect - Theoretical ExplanationsQuark 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
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?
EMC Effect in 3He and 4He
Current data do not differentiate between A-dependence or -dependence.
Can do exact few-body calculations, and high-precision measurement
Fill in high-x region – transition from rescaling to Fermi motion?
SLAC fit to heavy nuclei(scaled to 3He)
Calculations by Pandharipande and Benhar for 3He and 4He
Approximate uncertainties for 12 GeV coverage
Hermes data
Do multi-quark clusters exist in the nuclear wavefunction? Do they contribute significantly to the EMC effect?
How to answer: tag overlapping nucleons…
12 GeV gives access to the high-x, high-Q2 kinematics needed to find multi-quark clusters
Correlated nucleon pair
Six-quark bag (4.5% of wave function)
Fe(e,e’)5 PAC days
Multi-quark clusters are accessible at large x (>>1) and high Q2
Mean field
Is the EMC effect a valence quark phenomenon, or are sea quarks also involved?
Drell-Yan data from Fermilab, showing no clear excess of anti-quarks in nuclei
Incidentquark,
x1
Targetanti-quark,
x2 +
-
0.5
1.0
gluons
sea
valence
0.1 1.0
D
Ca
F
F
2
2
S. Kumano, “Nuclear Modification of Structure Functions in Lepton Scattering,” hep-ph/0307105
JLab 12
• Sea and valence expected to be quite different
• Detect +, -, (K+, K-), do flavor decomposition
x
Flavor-tagged EMC Effect
Global fit of electron and muon DIS experiments and Drell-Yan data
What is the role of relativity in the description of the EMC effect? What can be learned from spin?
• 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!
Surprises: 23 years ago – EMC effect17 years ago – the ‘spin crisis’
will there be another ‘spin crisis’ in nuclei?
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
g1(A) – “Polarized EMC Effect” – Some Solid Target Possibilities
Nuclide Compound Polarization (%)
6Li 6LiD 457Li 7LiD 9011B C2N2BH13 7513C 13C4H9OH 6519F LiF 90
Proton embedded in 7Li with over 50% polarization!
Polarized EMC EffectAssumes 11 GeV beam, 40% target polarization, 80% beam polarization and running for 70 days; study by Vipuli Dharmawardane
Systematic error target is < 5%
p
A
gLig
1
71
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?
“Polarized EMC Effect” – Flavor Tagging
• Can perform semi-inclusive DIS on sequence of polarized targets, measuring + and -, decompose to extract uA(xA), dA(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
uA(xA)
u(x)
x
uv(x)
free nucleon+ scalar field+ Fermi+ vector field(total)
dv(x)
W. Bentz, I. Cloet, A. W. Thomas
Rat
ios
uA(xA)
u(x)
nuclear matternuclear matter
Precision Tests of the Standard Model
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
Parity Violating Electron DIS
APV GFQ2
2a(x) f (y)b(x)
a(x) C1iQi f i(x)
Qi2 f i(x)
b(x) C2iQi f i(x)
Qi2 f i(x)
fi(x) are quark distribution functions
e-
N X
e-
Z* *
a(x) 3
10(2C1u C1d )
For an isoscalar target like 2H, structure functions largely cancels in the ratio:
b(x) 3
10(2C2u C2d )
uv (x) dv (x)
u(x) d(x)
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
2H 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
The 12 GeV Upgrade Project: Status and Schedule
12 GeVPHYSICS
FY07 FTEs BY MONTH
-
5
10
15
20
25
30
35
40
45
Oct-06 Nov-06 Dec-06 Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07
FT
Es
DOE Generic Project Timeline
We are hereDOE Reviews
2004-2005 Conceptual Design (CDR) - finished
2004-2008 Research and Development (R&D) - 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
(based on funding profile provided April 2006)
12 GeV Upgrade: Phases and Schedule
• 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; A&E firm authorized to proceed with 60% design of Hall D Complex; project design phase now in full swing!
12 GeV Upgrade: Recent News
12 GeV Physics Plans for FY07
• Detailed plans for FY07 R&D and PED have been cast into a resource-loaded schedule– 250 activities and milestones– Approximately 25 paid FTE’s matrixed from ~50 laboratory staff– Additional 17 FTE’s of contributed university labor– Incorporates ESH&Q activities and milestones
• Major R&D 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
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.
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!
BACKUP TRANSPARENCIES
Reminder: semi-inclusive DIS
Cross section ~ qq
hq zDxq,
)()(
hadronE
z
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’
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! S1/2
P3/2