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Diana Parno

d 2 n and A 1 n : Recent Results and Outlook. CENPA, University of Washington. 2013 Users’ Group Meeting, Jefferson Lab. Diana Parno. Outline. Deep inelastic scattering and structure functions d 2 and A 1 for the neutron E06-014 in Hall A at 6 GeV Outlook at 12 GeV.

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Diana Parno

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  1. d2n and A1n: Recent Results and Outlook CENPA, University of Washington 2013 Users’ Group Meeting, Jefferson Lab Diana Parno

  2. Outline Deep inelastic scattering and structure functions d2 and A1 for the neutron E06-014 in Hall A at 6 GeV Outlook at 12 GeV Diana Parno - May 29, 2013

  3. Deep Inelastic Scattering • Start with a polarized electron and a polarized nucleon • They exchange a virtual photon • Virtual photon-nucleon vertex contains nucleon structure information • Inclusive measurement: only detect scattered electrons k’ k Incident electron Scattered electron q Virtual photon Incident nucleon p Diana Parno - May 29, 2013

  4. Nucleon Structure Functions • To describe scattering from a complex structure – like a nucleon – you need structure functions: k’ θ k Scattering from a point particle is straightforward: Diana Parno - May 29, 2013

  5. Polarized Structure Functions • Now add relative spin orientations to the picture • F1(x, Q2) and g1(x, Q2) have simple meanings in the quark-parton model: Diana Parno - May 29, 2013

  6. d2 Bag Model QCD Sum Rules Lattice QCD Chiral Soliton Data We need precise data at large x • Clean probe of twist-3 physics (quark-gluon correlations) Proton d2 • 2σ discrepancy between lattice prediction and measurement of neutron d2 Neutron Predictions and Data From g1 and g2, we form the quantity d2 for the nucleon: Diana Parno - May 29, 2013

  7. A1 Photon spin Nucleon spin Photon spin Nucleon spin Same helicities: Opposite helicities: • Flavor decomposition of spin structure from A1n and A1p combined Picture the polarizations at the hadron vertex: Diana Parno - May 29, 2013

  8. More Neutron DIS Data Needed • ... at Q2 ≈ 5 GeV2 and large x. A1n • ... at large x. pQCD predicts d2n x Q2 (GeV2) Leader, Sidorov and Stamenov, PRD 75: 074027 (2007) Avakian et al, PRL 99: 082001 (2007) Diana Parno - May 29, 2013

  9. Outline Deep inelastic scattering and structure functions d2 and A1 for the neutron E06-014 in Hall A at 6 GeV Outlook at 12 GeV Diana Parno - May 29, 2013

  10. E06-014 in Hall A Beam direction Compton Polarimeter Polarized electron beam Left high-resolution spectrometer BigBite spectrometer Polarized 3He target Feb-Mar 2009 Ee = 4.7 and 5.9 GeV Inclusive asymmetries Inclusive cross sections Diana Parno - May 29, 2013

  11. Polarized 3He Target • Hybrid spin-exchange optical pumping • Polarize Rb via optical pumping • Rb-K interactions polarize K • K-3He interactions polarize 3He AmeyaKolarkar, PhD thesis, 2008 87% of the time, the neutron carries the 3He nuclear spin Polarized 3He target ≈ polarized neutron target Diana Parno - May 29, 2013

  12. E06-014 Kinematics DIS region Resonance region Diana Parno - May 29, 2013

  13. Preliminary E06-014 Results • What you won’t see accounted for: • Radiative corrections (nearly complete) • Asymmetries from e+/e- pairs • Some systematics (cut selection, kinematics) • More sophisticated nuclear corrections Deconvolution method in progress – Melnitchouk et al. • What you willsee accounted for: • Beam polarization • Target polarization • N2 dilution in target cell • Dilution from e+/e- pairs produced in π0 decay • Basic nuclear corrections (effective polarization model) Diana Parno - May 29, 2013

  14. x2g1n (d2n integrand) Lacks radiative / pair-production corrections Systematic error bars will grow Preliminary nuclear-correction method Diana Parno - May 29, 2013

  15. x2g2n (d2n integrand) Lacks radiative / pair-production corrections Systematic error bars will grow Preliminary nuclear-correction method Diana Parno - May 29, 2013

  16. A1He-3 DIS Resonance E06014 (Ee = 5.89 GeV) E06014 (Ee = 4.74 GeV) E142 E99-117 E01-012 (resonance) Lacks radiative / pair-production corrections Systematic error bars will grow No nuclear correction yet Diana Parno - May 29, 2013

  17. Outline Deep inelastic scattering and structure functions d2 and A1 for the neutron E06-014 in Hall A at 6 GeV Outlook at 12 GeV Diana Parno - May 29, 2013

  18. E12-06-121: d2n at 12 GeV • Measure d2n at 4 constant Q2 values • Error at each point will be comparable to E06-014 Approved with A- rating 29 days in Hall C Spokespeople: T. Averett W. Korsch Z.-E. Meziani B. Sawatzky SHMS HMS E06-014 kinematics Ee=11 GeV, upgraded 3He target SHMS: large x range at nearly constant Q2 HMS: fill in gaps at low x Diana Parno - May 29, 2013

  19. E12-06-110: A1n at 12 GeV Approved with A rating 36 days in Hall C • Precise DIS A1n measurements from 0.25 ≤ x ≤ 0.77 30° 12.5° Push to high x Spokespeople: G. Cates J.-P. Chen Z.-E. Meziani X. Zheng Explore Q2 dependence Ee=11 GeV, upgraded 3He target Simultaneous HMS, SHMS measurements improve statistics Diana Parno - May 29, 2013

  20. E12-06-122: A1n at 12 GeV Approved with A- rating 23 days in Hall A • Third set of Q2 values for interpolation • Test of open-geometry measurement technique Spokespeople: T. Averett G. Cates N. Liyanage G. Rosner B. Wojtsekhowski X. Zheng Ee=6.6, 8.8 GeV; upgraded 3He target BigBite: Primary measurement Left HRS: Cross-check (lower statistics) Diana Parno - May 29, 2013

  21. Conclusions • DIS measurements of d2nand A1n at large x will • test Lattice QCD and pQCD • probe higher-twist effects • explore nucleon spin structure • E06-014 data will address these questions • Stay tuned for final results • The 12-GeV program will improve the picture even further • Push to higher x • Explore Q2 evolution Diana Parno - May 29, 2013

  22. K. Allada W. Armstrong T. Averett F. Benmokhtar W. Bertozzi A. Camsonne M. Canan G. D. Cates C. Chen J.-P. Chen S. Choi E. Chudakov F. Cusanno M. M. Dalton W. Deconinck C. W. de Jager X. Deng A. Deur C. Dutta L. El Fassi D. Flay G. B. Franklin M. Friend H. Gao F. Garibaldi S. Gilad R. Gilman O. Glamazdin S. Golge J. Gomez L. Guo O. Hansen D. W. Higinbotham T. Holmstrom J. Huang C. Hyde H. F. Ibrahim X. Jiang G. Jin J. Katich A. Kelleher A. Kolarkar W. Korsch G. Kumbartzki J. J. LeRose R. Lindgren N. Liyanage E. Long A. Lukhanin V. Mamyan D. McNulty Z.-E. Meziani R. Michaels M. Mihovilovič B. Moffit N. Muangma S. Nanda A. Narayan V. Nelyubin B. Norum Nuruzzaman Y. Oh D. S. Parno J. C. Peng M. Posik X. Qian Y. Qiang A. Rakhman R. D. Ransome S. Riordan A. Saha B. Sawatzky M. H. Shabestari A. Shahinyan S. Širca P. Solvignon R. Subedi V. Sulkosky A. Tobias W. Troth D. Wang Y. Wang B. Wojtsekhowski X. Yan H. Yao Y. Ye Z. Ye L. Yuan X. Zhan Y. Zhang Y.-W. Zhang B. Zhao X. Zheng The E06-014 Collaboration (Hall A) Co-spokesperson PhD (in progress) PhD (complete)

  23. Further Acknowledgments • The Transversity collaboration for many of the pictures used in this talk Thank you! The DOE Office of Science The Accelerator Division The “Big Family” collaboration for setup help Diana Parno - May 29, 2013

  24. Backup Slides Diana Parno - May 29, 2013

  25. DIS Vocabulary k k’ θ • Four-momentum transfer • Electron energy loss (lab frame) • Bjorken x(momentum fraction) Let’s define some useful variables in the lab frame (nucleon rest frame) Diana Parno - May 29, 2013

  26. Polarized Structure Functions • Longitudinally polarized beam and transversely polarized target k’ θ k Longitudinally polarized beam and target Diana Parno - May 29, 2013

  27. Polarized Electron Beam • Møller scattering (e-e- e-e-) • Destructive measurement • Two measurement methods for E06-014: From Hall A Møller Group • Compton scattering (e-γe-γ) • Non-destructive measurement • Circularly polarized photons • Longitudinally polarized electrons Asymmetry Photon energy The electrons on target are longitudinally polarized…but how well polarized are they? Diana Parno - May 29, 2013

  28. BigBite • Gas Čerenkov • Exclude pions from trigger Scattered particles • 2 lead-glass calorimeters • Energy • Particle identification • Scintillator plane • Timing Adapted from XinQian, PhD thesis, 2010 • 3 multiwire drift chambers • Tracking • Momentum Diana Parno - May 29, 2013

  29. 5.9-GeV Cross Sections Radiative corrections have not been applied Diana Parno - May 29, 2013

  30. 4.7-GeV Cross Sections Radiative corrections have not been applied Diana Parno - May 29, 2013

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