Spin Based Physics at Jefferson Lab

Hugh Montgomery

October 10, 2008

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Outline• State-of-the-art technologies

•   Spin physics at Jefferson Laboratory – The first ten years– The remaining “6 GeV” program

• Jlab 12 GeV Upgrade

• ELIC

• Summary

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Spin, Current, and Beam Delivery @CEBAF

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Polarimeter I ave Px Py Pz

Injector Mott 2 A x xHall A Compton 70 A xHall A Moller 1 A x xHall B Moller 10 nA x xHall C Moller 1 A x

Under development<0.5% Atomic Beam Polarimeter (Hall A)<1% Compton Polarimeter (Hall C)

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Polarized Targets at JLab

Hall A: 3He

GEn, SSAs

Transversity

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Hall B: eg1Dynamically polarized NH3 ND3,

Q2 evolution of Nucleon SpinStructure, DVCS

Hall B: FROST Frozen Spin Target, Butanol

“Missing” N* Search.

Hall C: Dynamically polarized, NH3 ND3

GEn, SANE, g1

p, g1d

HDIce from BNL under development:Polarized neutron target for N* expts.

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Highlights: first 10 Years of Physics at JLab• QCD and the Structure of Hadrons

– Discovery of unexpected behavior of GEp ; Measurement of GE

n

– Strangeness content of the proton– The deformation of and N* transition form factors– Spin dependent structure functions:

Bjorken & GDH sum rule; g1n; |∆ G|– Measurement of the pion form factor – Exploration of duality, pQCD counting rules, color transparency – Initial exploration of Generalized Parton Distributions (GPDs)

towards mapping of angular momentum in the proton• Nuclei: From Structure to Exploding Stars

– New information on correlations in nuclei and the role of the tensor force

– Studies of hypernuclei – better than 400keV resolution• In Search of the New Standard Model

– factor 5 increase in precision of Standard Model couplings

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Jefferson Lab – Spin Structure Functions g1(x,Q2)

World data on the proton including Jlab

covering the resonance region and overlapping with the DIS

domain

Similar coverage for the Deuteron

Enormous contribution towards understanding the spin of and in

the nucleon.

Halved the uncertainties in the parton distribution functions.

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Preliminary High-Q2 results for GEn

• GEn at 1.7 GeV2 is well above GGalster.

• GEn at 3.4 GeV2 is closer to GGalster and far below CQM and GPD

• Final accuracy for 3.4 GeV2 expected to improved by factor 1.5 • Next release will be the result at 2.5 GeV2

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Science Remaining for CEBAF@6 GeV? • Completion of data-taking for milestone-related physics

– Baryon spectroscopy (FROzen Spin Target and HDIce target data)– DVCS (CLAS Phase II and Hall A separation of BHDVCS and DVCS2)– Structure function moments (SANE, d2

n)– …..

• Important new data on:– Strange quark distributions (HAPPEx III)– Hypernuclear spectroscopy – Correlations (4He(e,e’pN) data extended)– Dispersive effects in electron scattering [(e+,e+) vs (e-,e-)]– Transversity– …..

• Unique new experimental directions:– PREx (rms radius of neutron dist. for nuclear structure, astrophysics, and

atomic PV Standard Model tests)– QWeak (Weak charge of the proton for a Standard Model Test)

• Measurements in new areas of research that will be a focus of science with the 12 GeV Upgrade, such as:– Single spin asymmetries– DVCS w/ Longitudinally polarized target – PVDIS, …..

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Deep Virtual Compton Scattering : Gen. Parton Dists?

Three A-rated experiments combined allow the separation of Generalized Parton Distributions.

Hall A Experiment will separate the Bethe-Heitler from the Deep Compton

Hall B E1-DVCS and EG1-DVCS are scheduled to run in 2008/2009 and use polarized electron beams and longitudinally polarized proton target.

HD-DVCS is conditionally approved (relying on the operation of the HD-Ice target with electron beams) will use a transversely polarized proton (and deuterium) target.

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All Data & Fits Plotted at 1 σ

HAPPEx: H, HeG0: H, PVA4: HSAMPLE: H, D

Isovector weak charge

Isos

cala

r wea

k ch

arge

Standard Model Prediction

Weak Couplings

Q-weak expected precision

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TJNAF E06-002: PREX A Clean Measurement of the Neutron Skin in 208Pb

Q2~0.008 GeV2, E = 1 GeV, 05Z0 : Clean Probe Couples Mainly to Neutrons

( Dany Page )

δ(APV) ~ ± 3%δ(Rn) ~ ±1%

Physics Implications• Nuclear Equation of State• Neutron stars

• Size and density• Crust• Cooling

• Heavy Ion Collisions• Atomic Parity Violation

Subject of Aug 08 JLab

workshopthat attracted

70 experts from

many different fields

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12 GeV Upgrade Current Status• Technical Status

• R&D 98% complete• Overall PED 76% complete (Civil design 100% complete)• 18 major procurement packages issued

• bid packages under review for 5 major procurements

• 2009-2014 Construction• Is starting FY2009• Accelerator shutdown – May 2011 through Oct 2011 (6 months)• Accelerator shutdown start mid-May 2012 ; commissioning mid-May 2013

• 2013-2015 Hall Pre-Ops (beam commissioning)• Hall A commissioning start ~October 2013• Hall D commissioning start ~April 2014• Halls B and C commissioning start ~October 2014

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12 GeV Upgrade

Enhanced capabilities in existing Halls

New Hall

CHL-2

Maintain capability to deliverlower pass beam energies

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12 GeV Upgrade

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Measuring High-x Structure FunctionsREQUIRES:• High beam polarization• High electron current• High target polarization• Large solid angle spectrometers

12 GeV will access the regime (x > 0.3), where valence quarks dominate

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Unraveling 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

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sin 2(Qw ) = 0.00025

0.000008 fm

25 TeV mass scale

ee ~ 25 TeVJLab Møller

ee ~ 15 TeVLEP200

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

Møller Parity-Violating Experiment: New Physics Reach

sin 2(Qw ) = 0.00025

0.000008 fm

25 TeV mass scale

sin 2(Qw ) = 0.00025

0.000008 fm

25 TeV mass scale

ee ~ 25 TeVJLab Møller

ee ~ 15 TeVLEP200

LHCComplementary; 1-2 TeV reach

New Contact Interactions

sin2W ~ 0.00025

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Hall D GluEX uses polarized photons

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Electron Ion Collider• Recommended as a generic capability by:

– NSAC Long Range Report– IUPAP WG9 Working Group on world-wide nuclear facilities

• Candidate Facilities with different key characteristics– LHeC at CERN– eRHIC at Brookhaven National Laboratory– ELIC – ELectron Ion Collider at Jlab– MANUEL at FAIR-GSI

• Natural Extension of Jlab nuclear physics agenda• Issues

– Physics Case(s) not yet broadly accepted– Cost scale is thought to be large

• Collaboration with BNL • Directors to commission an advisory group to help advise prepare the

case for the next NSAC Long Range Plan. Group exists, charge drafted, need date.

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ELectron Ion Collider

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Spin with ELIC Ring-Ring (R-R) design taking CEBAF advantage as full

energy polarized injector• 12 GeV CEBAF Upgrade polarized source/injector already meets beam

requirement of R-R design (0.1 mA)

Spin Capabilities• Longitudinal polarization at the IP for both beams • Transverse polarization of ions• Spin-flip of both beams• All polarizations >70% desirable

“Figure-8” ion and lepton storage rings • Ensure spin preservation and ease of spin manipulation• No spin sensitivity to energy for all species.

Luminosity of 3 ·1034 cm-2s-1 (per IP, 4 IP’s) at 0.5 GHz collision frequency, with a 10σ aperture for proton and 13σ aperture for electrons

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Explore the structure of the nucleon

• Parton distribution functions• Longitudinal and transverse

spin distribution functions• Generalized parton

distributions• Transverse momentum

distributions

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RHIC-Spin region

Precisely image the sea quarksSpin-Flavor Decomposition of the Light Quark Sea

| p = + + + …>u

u

d

u

u

u

u

d

u

u

dd

d Many models predict

u > 0, d < 0

No competition foreseen!

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The physics program thus far has been dominated by that part depending on SPIN

The remaining 6 GeV Program is dominated by SPIN

The 12 GeV Program, as far as we understand it now, is dominated by SPIN

ELIC Capabilities emphasize SPIN

At JLAB SPIN is very much an everyday tool and will likely remain so.

Jefferson Lab and Spin