Spin Based Physics at Jefferson Lab Hugh Montgomery October 10, 2008

2 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

3 Spin, Current, and Beam 3 Under development <0.5% Atomic Beam Polarimeter (Hall A) <1% Compton Polarimeter (Hall C)

4 Polarized Targets at JLab Hall A: 3 He G E n, SSAs Transversity 4 Hall B: eg1 Dynamically polarized NH 3 ND 3, Q 2 evolution of Nucleon Spin Structure, DVCS Hall B: FROST Frozen Spin Target, Butanol “Missing” N* Search. Hall C: Dynamically polarized, NH 3 ND 3 G E n, SANE, g 1 p, g 1 d HDIce from BNL under development: Polarized neutron target for N* expts.

5 Highlights: first 10 Years of Physics at JLab QCD and the Structure of Hadrons –Discovery of unexpected behavior of G E p ; Measurement of G E n –Strangeness content of the proton –The deformation of  and N* transition form factors –Spin dependent structure functions: Bjorken & GDH sum rule; g 1n ; |∆ 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

6 Jefferson Lab – Spin Structure Functions g 1 (x,Q 2 ) 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. 6

7 Preliminary High-Q 2 results for G E n G E n at 1.7 GeV 2 is well above G Galster. G E n at 3.4 GeV 2 is closer to G Galster and far below CQM and GPD Final accuracy for 3.4 GeV 2 expected to improved by factor 1.5 Next release will be the result at 2.5 GeV 2

8 Science Remaining for 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 BH  DVCS and DVCS 2 ) –Structure function moments (SANE, d 2 n ) –….. Important new data on: –Strange quark distributions (HAPPEx III) –Hypernuclear spectroscopy –Correlations ( 4 He(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) –Q Weak (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, …..

9 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.

10 All Data & Fits Plotted at 1 σ HAPPEx: H, He G 0 : H, PVA4: H SAMPLE: H, D Isovector weak charge Isoscalar weak charge Standard Model Prediction Weak Couplings Q-weak expected precision

11 TJNAF E06-002: PREX A Clean Measurement of the Neutron Skin in 208 Pb Q 2 ~0.008 GeV 2, E = 1 GeV, Z 0 : Clean Probe Couples Mainly to Neutrons ( Dany Page ) δ(A PV ) ~ ± 3% δ(R n ) ~ ±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 workshop that attracted 70 experts from many different fields

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

13 12 GeV Upgrade Enhanced capabilities in existing Halls New Hall CHL-2 Maintain capability to deliver lower pass beam energies

14 12 GeV Upgrade

15 Measuring High-x Structure Functions REQUIRES: 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

16 Unraveling the Quark WNC Couplings 12 GeV:  (2C 2u -C 2d )=0.01 PDG: ± 0.24 Theory: A V V A Vector quark couplings Axial-vector quark couplings

17  sin 2 (  w ) =  fm  25 TeV mass scale  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 GeV Møller Møller Parity-Violating Experiment: New Physics Reach  sin 2 (  w ) =  fm  25 TeV mass scale  sin 2 (  w ) =  fm  25 TeV mass scale  ee ~ 25 TeV JLab Møller  ee ~ 15 TeV LEP200 LHC Complementary; 1-2 TeV reach New Contact Interactions   sin 2  W ~

18 Hall D GluEX uses polarized photons

19 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.

20 ELectron Ion Collider

21 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 ·10 34 cm -2 s -1 (per IP, 4 IP’s) at 0.5 GHz collision frequency, with a 10σ aperture for proton and 13σ aperture for electrons

22 Explore the structure of the nucleon Parton distribution functions Longitudinal and transverse spin distribution functions Generalized parton distributions Transverse momentum distributions

23 RHIC-Spin region Precisely image the sea quarks Spin-Flavor Decomposition of the Light Quark Sea | p = … > u u d u u u u d u u d d d Many models predict  u > 0,  d < 0 No competition foreseen!

24  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