1 / 54

Neutron Transversity with BigBite + Super BigBite C12-09-018

Neutron Transversity with BigBite + Super BigBite C12-09-018. Andrew Puckett, LANL Hall A Collaboration Meeting 6/10/11. Outline. Physics Motivation Experiment Layout BigBite as e arm SBS as h arm High Luminosity 3 He target Monte Carlo Simulation Kinematic Coverage Azimuthal Coverage

milek
Download Presentation

Neutron Transversity with BigBite + Super BigBite C12-09-018

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neutron Transversity with BigBite + Super BigBiteC12-09-018 Andrew Puckett, LANL Hall A Collaboration Meeting 6/10/11 Hall A Collaboration Meeting

  2. Outline • Physics Motivation • Experiment Layout • BigBite as e arm • SBS as h arm • High Luminosity 3He target • Monte Carlo Simulation • Kinematic Coverage • Azimuthal Coverage • Projected Physics Impacts • Relation to Similar Experiments • Conclusions Hall A Collaboration Meeting

  3. Semi-Inclusive Deep Inelastic Scattering • In addition to usual DIS observables, SIDIS reaction N(e,e’h)X provides access to: • quark flavor • quark transverse motion • quark transverse spin • Extra degrees of freedom relative to inclusive DIS  more numerous and complicated structure functions • TMD approach: beyond collinear factorization, 8 leading-twist TMDs Hall A Collaboration Meeting

  4. SIDIS Kinematic Definitions • Incident (scattered) lepton four-momentum: l = (E,k), l’ = (E’,k’) • Scattered hadron four-momentum Ph = (Eh, ph) • Azimuthal angles defined according to Trento convention (right) Hall A Collaboration Meeting

  5. Transverse SSAs in SIDIS • Transverse target spin-dependent cross section for SIDIS • Collins effect—chiral-odd quark transversity DF; chiral-odd Collins FF • Sivers effect—access to quark OAM and QCD FSI mechanism • “Pretzelosity” or Mulders-Tangerman function—access to wavefunction components differing by 2 units of OAM Different TMD contributions isolated via azimuthal modulations Hall A Collaboration Meeting

  6. Physics of Transverse SSAs—Sivers Effect • Sivers function is a correlation between kT of unpolarized quarks and nucleon transverse spin; • Connected to quark OAM • Generates left-right asymmetry in the SIDIS cross section (polarization normal to hadron production plane): • Naive T-odd: presence requires a phase; generated (in SIDIS) by QCD FSI (Brodsky, Hwang, Schmidt) • Based on gauge invariance, QCD predicts sign change of Sivers function between SIDIS and Drell-Yan production • Needs experimental verification! • Crucial test for TMD factorization approach to SSAs Hall A Collaboration Meeting

  7. Physics of Transverse SSAs—Collins Effect • Transversity distribution expresses the correlation between quark and nucleon transverse polarization. • Accessible in SIDIS by coupling to spin-dependent Collins fragmentation function: • Gluon transversity vanishes due to helicity conservation quark transversity is “valence-like” • Soffer bound: • For non-relativistic quarks, h1 = g1, difference between helicity and transversity is a signature of relativistic effects • First moment of h1 = tensor charge; calculable in lattice QCD Hall A Collaboration Meeting

  8. Transversity and Collins FFs from SIDIS and e+e- Data u and d quark transversity Favored/Unfavored Collins FFs • NPB 191, 98 (2009): Phenomenological global fit of quark transversity distributions and Collins FFs to latest HERMES proton + COMPASS deuteron SIDIS data and BELLE e+e- data • Data favor opposite sign u and d quark transversity, constraints from pre-2007 data are limited • Latest fit favors h1d close to Soffer limit. Hall A Collaboration Meeting

  9. Transversity and Collins FFs from SIDIS and e+e- Data COMPASS deuteron Collins AUT HERMES proton Collins AUT • Features: COMPASS data compatible with zero; HERMES data show clear non-zero signals, opposite sign between π+ and π- • Opposite sign of u and d transversity; • Favored and unfavored Collins FFs opposite sign, “unfavored” larger in magnitude! Hall A Collaboration Meeting

  10. Sivers Functions from SIDIS Data • EPJ A, 39, 89 (2009) • Extraction and flavor separation of Sivers functions for all light-quark/antiquark flavors using phenomenological ansatz • u and d quark Sivers of opposite sign, similar magnitude • Large K+ Sivers moments appear to require a positive anti-s Sivers function • ubar, s, not presently distinguishable from zero • Negative dbar favored Hall A Collaboration Meeting

  11. Sivers Functions from SIDIS Data HERMES and COMPASS data for Sivers AUT Hall A Collaboration Meeting

  12. Experiment C12-09-018—PAC Status • Conditionally approved by PAC34 • Technical/feasibility concerns including RICH operation, high-rate tracking, trigger/DAQ, target upgrades, etc. • Returned to PAC37, largely satisfied PAC34 technical concerns (we think). Approval still conditional on more detailed justification of physics impacts: • In the words of PAC37: “Return to PAC38 proving sufficient statistics in multi-dimensional space” • PAC37 final report??? • Return to PAC38: Importance of first grading of SIDIS proposals Hall A Collaboration Meeting

  13. Experiment C12-09-018 Collaboration • Spokespeople: • Gordon Cates, UVA • Evaristo Cisbani, INFN • Gregg Franklin, CMU • Andrew Puckett, LANL • Bogdan Wojtsekhowski, JLab • 100+ collaborators from ~30 institutions (so far) Hall A Collaboration Meeting

  14. Experiment C12-09-018—Run Plan • 40 (20) days production at E=11 (8.8) GeV on transversely polarized 3He target • 65% target polarization • 4×1036 cm-2 s-1 en lumi. • Detect π±/π0/K± simultaneously in same setting • RICH PID • Vertically symmetric acceptance • SBS at 14 degrees as hadron arm • BigBite at 30 degrees as electron arm Hall A Collaboration Meeting

  15. Experiment C12-09-018: Conceptual Layout • Electron arm (BigBite) at 30° • Hadron arm (SBS) at 14° • Both arms: large solid angle and “infinite” momentum bite. • Upgraded high-luminosity 3He target, 60 cm long; target spin can be oriented in any transverse direction, we will use 8 to cover full azimuthal phase space • 10X larger angular acceptance compared to 6 GeV transversity Hall A Collaboration Meeting

  16. Hadron arm: Super BigBite Spectrometer (SBS) • http://hallaweb.jlab.org/12GeV/SuperBigBite/ • Warm dipole magnet 48D48, Bdl = 2 Tm; cut in yoke for passage of beam pipe, reach to very forward angles. (Lambertson magnet, familiar concept in accelerator physics). • Detectors for SIDIS • GEMs: high-rate capability, high-resolution tracking; momentum/angle/vertex/RICH, resolution • HCAL: Iron-scint hadronic calorimeter; trigger + timing + coordinate measurement+reduce search area for high-rate tracking, AND π0 detection! • HERMES RICH: Hadron PID, full π/K/p separation 2 GeV<p<15 GeV Hall A Collaboration Meeting

  17. SBS Acceptance Studies (GEANT) • Top left: solid angle vs. momentum/vertex • almost constant, average = 40 msr • Top right: 2D correlations: angles, momentum, vertex (almost “boxlike”) • Bend angles vs. p for upbending and downbending particles, at 2.0 Tm field integral Hall A Collaboration Meeting

  18. The HERMES RICH Detector 5.5 GeV K+ REAL DATA from NIMA 479 (2002) 511 14.6 GeV e- 1.5 GeV p- • Full π/K/p separation (2 GeV < p < 15 GeV) based on dual-radiator (gas+aerogel) design • High segmentation (1,934 PMTs) = excellent resolution and high-rate capability • ~5 cm aerogel n=1.0304 • C4F10, n = 1.00137 • Operation in up to 90 G stray field in HERMES—expect similar or lower in SBS • Status • 1 detector, both aerogels from HERMES in storage @ UVa • Prototype construction underway @ W&M, with additional 64 PMTs Hall A Collaboration Meeting

  19. Electron arm: BigBite Spectrometer • Already used successfully in a large number of experiments, including E06-010 (transversity) • Detectors for SIDIS • Lead-glass preshower/shower for trigger and offline pion rejection; threshold = 1 GeV • GEM chambers (INFN) instead of MWDC: • Increase rate capability in high-luminosity environment • Improve resolution • Gas Cherenkov: trigger and pion rejection • Charge tagger: possible supplement to GC for neutral trigger suppression Hall A Collaboration Meeting

  20. 1.2 Tesla dipole magnet in front of detector stack • Positioned to subtend ~64 msr solid angle • Demonstrated performance at same angle/distance setting in E06-010 • Upgrade to GEM tracking to increase rate capability for higher luminosity and resolution at higher momenta • Upgrade gas Cherenkov (to working status) for improved trigger and electron PID BigBite Spectrometer Hall A Collaboration Meeting

  21. High Luminosity Polarized 3He Target • History of FOM increases in JLab polarized 3He experiments (top right) • New design with convection-driven flow • Fast replacement of polarized gas • Tolerate higher beam currents—support up to 60 μA, 60 cm long cell • 4 × 1036 cm-2 s-1 en luminosity • Decouple location of target chamber and pumping chamber; decouple magnetic field directions • Concept already demonstrated in bench tests • Fast spin orientation: ~every 2 minutes • Metal target cell in vacuum: reduce non-3He material on beamline—reduce background rates Bench test of convection flow Schematic of target chamber in vacuum Hall A Collaboration Meeting

  22. Monte Carlo Simulation • Physics event-generator + acceptance/resolution model only; no detector response yet • Physics: • CTEQ6 PDFs • DSS2007 FFs • Anselmino et al. Collins and Sivers effects • Generated large-statistics pseudo data set • Analyze to demonstrate extraction procedure (MLE) • Calculate statistical error • BigBite model: realistic acceptance/resolution calculations calibrated to E06-010 data • SBS model: “box” acceptance (detailed acceptance studies were not done by the time of the large simulation run, “box” acceptance is a good approximation) Hall A Collaboration Meeting

  23. 1D kinematic distributions (cross-section and acceptance-weighted) • Cover the valence region (0.1<x<0.7) at high Q2 • We can also cover down to lower x @ 1< Q2 with pre-scaled, low-threshold BigBite trigger, large cross section  only need a fraction of the triggers. • Cover the current fragmentation region (0.2<z<0.7) • Cover the most interesting pT range: large enough for non-zero asymmetries; small-enough that we believe TMD factorization is valid Hall A Collaboration Meeting

  24. Two beam energies for ~2 GeV2 lever arm in Q2 at same x! Q2, x, z, pT coverage vs. x Hall A Collaboration Meeting

  25. More on Q2-x Coverage C12-09-018, E=11 GeV C12-09-018, E=8.8 GeV E06-010, E=5.9 GeV Hall A Collaboration Meeting

  26. W, W’ and y coverage vs. x Hall A Collaboration Meeting

  27. Polar pT, ϕ plots, left to right = hadron angle, target angle, Collins angle, Sivers angle • Integrated over x, z • 8 target spin orientations: ±horizontal ±vertical, ±45°, ±135°. • Full ϕS angle coverage and ~50% ϕh coverage should allow reliable extraction of nearly all allowed Fourier moments with well-controlled systematics and minimal increase in error Hall A Collaboration Meeting

  28. Same as previous slide, with Cartesian representation Hall A Collaboration Meeting

  29. Increasing z   Increasing x Hall A Collaboration Meeting

  30. Increasing z   Increasing x Hall A Collaboration Meeting

  31. Increasing z   Increasing x Hall A Collaboration Meeting

  32. Increasing z   Increasing x Hall A Collaboration Meeting

  33. projected physics results & impacts Hall A Collaboration Meeting

  34. 3He Asymmetries: MLE Extraction • Two-term extraction of Collins and Sivers moments: linearized maximum-likelihood (weighted sum) estimators. • Symmetry of acceptance in target-spin dependent azimuthal angles cancels acceptance effects to first order (Besset et al., NIM 166, 515 (1979)) • θS is the polar angle between target spin and virtual photon direction (since target spin is perp. to beamline, θS is slightly different from 90° • Method can be expanded to arbitrary number of Fourier moments with reduced precision Hall A Collaboration Meeting

  35. Validity of Extraction Method Typical (x,z) bin: 3He asym. error = 0.06% (absolute)! • Helium-3 pi+ Sivers asymmetries, 2D binning in x and z, E = 11 GeV • Only 1/2 of expected statistics! • Points = extracted asymmetry • Curves = model asymmetry input to Monte Carlo Hall A Collaboration Meeting

  36. Projected Neutron Precision, Recall: ~87% ~8% ~1.5% Polarized 3He as effective polarized neutron target ~12 μA, 10 atm 3He = ~1036 cm-2s-1 en luminosity Effective nucleon polarization approach: Scopetta, PRD 75, 054005 (2007) Hall A Collaboration Meeting

  37. Comparison to Best Current Knowledge 1D binned neutron precision ~0.2% • HERMES/COMPASS published Sivers moments in 1D x binning—compared to our projected results, 1D binned x • Neutron predictions and uncertainty bands from Prokudin (Torino/Anselmino group) • Bands represent uncertainty in neutron from HERMES proton/COMPASS deuteron within a specific model; properly folded with our kinematics/acceptance. • In reality, the high-x region is totally unknown—results from pp suggest more flexible parametrizations may be needed Hall A Collaboration Meeting

  38. Neutron Sivers Moments in 6x6 x, pT Bins Typical Error ~0.5% • Some correlation between x, pT in our acceptance but good precision in wide two-dimensional coverage: Asymmetries at large pT could be as large as 20-50%!!! Hall A Collaboration Meeting

  39. Shrinking the Error Corridors • A. Prokudin generously ran a small subset of our projected results through Torino group’s global fit machinery; π+ Sivers moments at E = 11 GeV. • Left: >5X shrinking of n(e,e’ π+)X Sivers AUT band • Right: reducing the uncertainty in d quark Sivers in six-flavor extraction • Experiment will provide π±/π0/K± at similar precision (Kaon errors 2-3X pion errors) for both E = 8.8 GeV and E = 11 GeV Collins/Sivers (and Pretzelosity) Hall A Collaboration Meeting

  40. Collins Moments—1D Comparison Typical Error ~ 0.2% • Existing Collins parametrization predicts generally small (few-% level) neutron asymmetries. This makes the measurement of transversity very difficult cf. Sivers! • Parametrization enforces Soffer bound on d quark transversity distribution • Some kinematic suppression of asymmetry due to large y • If Soffer bound is violated, as suggested by some theorists and by E06-010 data at ~2σ level, asymmetries at large x could be substantially larger. Hall A Collaboration Meeting

  41. Collins Moments: 2D 5x6 x, z bins Typical Error ~0.5% • Almost completely uncorrelated x, z coverage • Independently constrain Collins FF • ~10-30% accuracy for 2D kinematic bins relative to this model Hall A Collaboration Meeting

  42. Comparison to Other Experiments • Crude Comparison of FOM between different 3He experiments • Relative asymmetry uncertainty squared ~ N events × A2 Hall A Collaboration Meeting

  43. SBS vs. SOLID phase space after SIDIS cuts • At 11 GeV, SBS+BB has significantly higher x, Q2 reach (complementary), lower counting rate due to large angles, large Q2 • pT coverage: SBS has similar or greater high-pT coverage; less low-pT coverage at small x Hall A Collaboration Meeting

  44. SBS/BigBite and SOLID: Our Perspective • SBS+BB SIDIS will advance experimental knowledge of SIDIS SSA for charged and neutral pions and kaons, by at least a factor of 10 wrt current knowledge (~100X stats. of HERMES), at low incremental cost relative to approved form factor program, and on a relatively fast timeline • Apart from SBS+BB, virtually no SIDIS data between now (E06-010) and SOLID* • Large parallel effort in transverse spin physics in Drell-Yan and pp at RHIC/FNAL/etc. in the next few years • SOLID will perform the “ultimate” fully differential kinematic binning @ 12 GeV (for π±), but presumably after SBS form factor program and Möller (long timeline) • C12-09-018 will help to advance this field, by providing urgently needed precision data, in a timely fashion, taking us “halfway” to the “ultimate” experiment, and with complementary kinematic coverage * COMPASS will publish update with ~2X current stats, CLAS12+HDice could provide proton data Hall A Collaboration Meeting

  45. Conclusions • SBS+BB is a natural configuration for SIDIS experiments, similar in many respects to the HERMES experiment, but at ~105 higher luminosity • Based on PAC37 recommendations, a significant physics simulation and analysis effort, along with theory support, has been performed to quantify the physics impact of C12-09-018 as clearly as possible. • Physics impact is now quite clear and “there for the taking” • Fits naturally into the 12 GeV JLab SIDIS program • We will return to PAC38 to seek full approval and grading Hall A Collaboration Meeting

  46. BACKUP SLIDES Hall A Collaboration Meeting

  47. Unique Advantages/Complementarity of Halls A/B/C for SIDIS Experiments @ JLab: Our View • Hall A • Polarized neutron measurements >1037 cm-2s-1 • Transverse/longitudinally polarized 3He targets @ high luminosity; • Large acceptance, open-geometry spectrometers • High-quality PID • Hall B • Polarized proton measurements; • Longitudinal/transverse proton targets at max. luminosity of CLAS12 ~1035 cm-2s-1 • Very large acceptance • Many-dimensional phase space • Provide information on closely related mechanisms, e.g. vector meson production • Hall C • Precision unpolarized cross section measurements w/ magnetic spectrometers • Require lower statistics compared to asymmetries • proton/deuteron • L/T separation • Understand SIDIS reaction mechanism Hall A Collaboration Meeting

  48. C12-09-018 Collaboration I G. Cates(spokesperson), H. Baghdasaryan, D. Day, P. Dolph, N. Kalantarians, R. Lindgren, N. Liyanage, V. Nelyubin, Al Tobias University of Virginia, Charlottesville, VA 22901 E. Cisbani(spokesperson), A. Del Dotto, F. Garibaldi, S. Frullani INFN Rome gruppo collegato Sanita and Istituto Superiore di Sanita, Rome, Italy G.B. Franklin(spokesperson), V. Mamyan, B. Quinn, R. Schumacher Carnegie Mellon University, Pittsburgh, PA 15213 A. Puckett (spokesperson), X. Jiang Los Alamos National Laboratory, Los Alamos, NM 87545 B. Wojtsekhowski (contact and spokesperson), K. Allada, A. Camsonne, E. Chudakov, P. Degtyarenko, M. Jones, J. Gomez, O. Hansen, D. W. Higinbotham, J. LeRose, R. Michaels, S. Nanda, L.Pentchev, A. Saha Thomas Jeerson National Accelerator Facility, Newport News, VA 23606 J. Annand, D. Hamilton, D. Ireland, R. Kaiser, K. Livingston, I. MacGregor, B. Seitz, and G. Rosner University of Glasgow, Glasgow, Scotland Hall A Collaboration Meeting

  49. C12-09-018 Collaboration II W. Boeglin, P. Markowitz, J. Reinhold Florida International University, Fl T. Averett College of William and Mary M. Khandaker, V. Punjabi Norfolk State University S. Riordan University of Massachusetts Amherst, Amherst, MA 01003 D. Nikolenko, I. Rachek, Yu. Shestakov Budker Institute, Novosibirsk, Russia M. Capogni INFN Rome gruppo collegato Sanita and ENEA Casaccia, Rome, Italy F. Meddi, G. Salme, G.M. Urciuoli INFN Rome and “La Sapienza" University, Rome, Italy S. Scopetta University of Perugia and INFN Perugia, Perugia, Italy G. De Cataldo, R. De Leo, L. Lagamba, S. Marrone, E. Nappi INFN Bari and University of Bari, Bari, Italy Hall A Collaboration Meeting

  50. C12-09-018 Collaboration III R. Perrino INFN Lecce, Lecce, Italy V. Bellini, A. Giusa, F. Mammoliti, G. Russo, M.L. Sperduto, C.M. Sutera INFN Catania and University of Catania, Catania, Italy M. Aghasyan, E. De Sanctis, D. Hasch, V. Lucherini, M. Mirazita, S.A. Pereira, P. Rossi INFN, Laboratori Nazionali di Frascati, Frascati, Italy A. D'Angelo, C. Schaerf, V. Vegna INFN Rome2 and University \Tor Vergata", Rome, Italy M. Battaglieri, R. De Vita, M. Osipenko, G. Ricco, M. Ripani, M. Taiuti INFN Genova and University of Genova, Genoa, Italy P.F. Dalpiaz, G. Ciullo, M. Contalbrigo, P. Lenisa, L. Pappalardo INFN Ferrara and University of Ferrara, Ferrara, Italy Hall A Collaboration Meeting

More Related