the 12 gev upgrade of jefferson lab: physics program and project status will brooks jefferson lab

68
The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Post on 21-Dec-2015

218 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Will Brooks

Jefferson Lab

Page 2: 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

Page 3: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 4: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 5: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 6: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Highlights of the12 GeV Science Program

Page 7: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 8: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Unlocking the secrets of QCD: confinement and space-time dynamics

Page 9: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 10: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• 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

Page 11: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• 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

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

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

Page 13: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 14: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• 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

Page 15: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 16: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Production length from JLab/CLAS 5 GeV data (Kopeliovich, Nemchik, Schmidt, hep-ph/0608044)

Page 17: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 18: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 19: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• 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

Page 20: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• Predicted results high-precision, will permit systematic studies

For more on this, see talk by K. Hafidi on Friday morning

Page 21: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

New and revolutionary access to the structure of the proton and neutron

Page 22: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Valence d-quark distributions poorly known

Page 23: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Valence structure function flavor dependence

Page 24: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Valence spin structure

p1A

Page 25: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Important complement to RHIC Spin data

Page 26: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Proton electric form factor

Page 27: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Neutron Magnetic Form Factor

Page 28: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Generalized Parton Distributions

Page 29: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

GPDs via cross sections and asymmetries

Page 30: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

New, comprehensive view of hadronic structure

Page 31: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 32: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

The quark structure of nuclei

Page 33: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 34: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 35: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 36: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 37: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• 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

Page 38: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 39: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 40: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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?

Page 41: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 42: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Do multi-quark clusters exist in the nuclear wavefunction? Do they contribute significantly to the EMC effect?

How to answer: tag overlapping nucleons…

Page 43: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 44: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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 +

-

Page 45: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 46: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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?

Page 47: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 48: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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!

Page 49: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 50: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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?

Page 51: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

“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

Page 52: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

Precision Tests of the Standard Model

Page 53: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 54: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 55: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 56: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 57: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

DOE Generic Project Timeline

We are hereDOE Reviews

Page 58: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 59: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

• 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

Page 60: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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

Page 61: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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.

Page 62: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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!

Page 63: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

BACKUP TRANSPARENCIES

Page 64: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab
Page 65: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab
Page 66: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab
Page 67: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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’

Page 68: The 12 GeV Upgrade of Jefferson Lab: Physics Program and Project Status Will Brooks Jefferson Lab

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