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Prospects in neutron transverse spin study with a polarized 3 He Target at 12 GeV JLab

Prospects in neutron transverse spin study with a polarized 3 He Target at 12 GeV JLab. (. A Third Joint meeting of Division of Nuclear Physics of American Physical Society and the Japanese Physical Society Oct 13-17, 2009

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Prospects in neutron transverse spin study with a polarized 3 He Target at 12 GeV JLab

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  1. Prospects in neutron transverse spin study with a polarized 3He Target at 12 GeV JLab ( A Third Joint meeting of Division of Nuclear Physics of American Physical Society and the Japanese Physical Society Oct 13-17, 2009 Waikaloa, Hawaii Haiyan Gao (高海燕) Duke University/TUNL Durham, NC, U.S.A.

  2. Outline Introduction First experiment at 6 GeV in Hall A @ JLab (Xiaodong Jiang) Transversity with 12 GeV at JLab Summary

  3. QCD Nucleon Structure Strong interaction, running coupling ~1 -- QCD: the theory of strong interaction -- asymptotic freedom (2004 Nobel) pQCD works at high energy -- interaction significant at intermediate energy quark-gluon correlations -- confinement interaction strong at low energy coherent hadron -- Chiral symmetry -- theoretical tools: pQCD, OPE, Lattice QCD, ChPT • Charge and magnetism (current) distribution • Nucleon: Electric GE and magnetic GM form factor • Spin distribution • Quark momentum and flavor distribution • Polarizabilities • Strangeness content • ….. E

  4. Leading-Twist Quark Distributions ( Eight parton distributions functions) non-vanishing integrating over Transversity: K - dependent, T-even K - dependent, T-odd

  5. Transversity • Three twist-2 quark distributions: • Momentum distributions: q(x,Q2) = q↑(x) + q↓(x) • Longitudinal spin distributions: Δq(x,Q2) = q↑(x) - q↓(x) • Transversity distributions: δq(x,Q2) = q┴(x) - q┬(x) • Some characteristics of transversity: • δq(x) = Δq(x) for non-relativistic quarks • δq and gluons do not mix → Q2-evolution simpler • Chiral-odd → not accessible in inclusive DIS • Rapidly developing field, worldwide efforts: BNL, Belle at KEK, CERN, DESY, JLab, FAIR project at GSI, … • It takes two chiral-odd objects to measure transversity

  6. Access Parton Distributions through Semi-Inclusive DIS Unpolarized Boer-Mulder Polarized Target Transversity Sivers Pretzelosity Polarized Beam and Target SL, ST: Target Polarization; e: Beam Polarization

  7. Separation of Collins, Sivers and pretzelocity effects through angular dependence

  8. AUTsin() from transv. pol. H target Simultaneous fit to sin( + s) and sin( - s) `Collins‘ moments `Sivers‘ moments • Sivers function nonzero (+) • orbital angular momentum ofquarks • Regular flagmentation functions • Non-zero Collins asymmetry • Assume q(x) from model, then • H1_unfav ~ -H1_fav • H1(BELLE) (arXiv:0805:2975) M. Anselmino et al, PRD75,05032(2007)

  9. Latest Results on Sivers From HERMES arXiv:0906.3918 Positive Sivers amplitude For ~zero for ~zero from COMPASS data On D target Negative Sivers For u quark and Positive for d quark

  10. Sivers asymmetries from COMPASS deuteron

  11. Collins asymmetries from COMPASS deuteron Phys. Lett. B 673 (2009) 127-135

  12. Experiments on polarized ``neutron’’ important!! Transverse Target SSA Measurement at Jefferson Lab Hall A Using a Polarized 3He Target (Neutron) First Experiment Completed Recently! Jefferson Lab Hall A E06-010/E06-011

  13. Jefferson Lab E06-010: Single Target-Spin Asymmetry in Semi-Inclusiven↑(e, e’p±)Reaction on a Transversely Polarized 3He Target • Performed in Jefferson Lab Hall A from 10/24/08-2/6/09 • Exceeded the approved goal • 7 PhD students • First measurement of the neutron Collins and Sivers asymmetries • x = 0.1 - 0.4 • Upgraded polarized 3He target • 20 min fast spin-flip • vertical polarization • improved performance • BigBite for e and HRSL for p and K. • BigBite detectors working well • Commissioned RICH in HRSL 16o g* BigBite 30o HRSL p e’ Polarized 3He Target e

  14. Nucleon Transversity at 11 GeV Using a Polarized 3He Target and SOLid in Hall A (Hall A Collaboration proposal) ( Beijing U., CalState-LA, CIAE, W&M, Duke, FIU, Hampton, Huangshan U., Cagliari U. and INFN, INFN-Bari and U. of Bari, INFN-Frascati, INFN-Pavia, Torino U. and INFN, JLab, JSI (Slovenia), Lanzhou U, LBNL, Longwood U, LANL, MIT, Miss. State, New Mexico, ODU, Penn State at Berks, Rutgers, Seoul Nat. U., St. Mary’s, Syracuse, Tel aviv, Temple, Tsinghua U, UConn, Glasgow, UIUC, Kentucky, Maryland, UMass, New Hampshire, USTC, UVa and the Hall A Collaboration Strong theory support, Over 130 collaborators, 40 institutions, 8 countries including all 6 GeV transversity collaboration

  15. Solenoid detector for SIDIS at 11 GeV (study done with Babar magnet, 1.5T) GEMs

  16. Experimental Overview • SoLID (proposed for PVDIS) • GEMs (tracking+vertex), • Calorimeter (trigger/pid), • CO2 gas cerenkov, aerogel (trigger/pid)‏ • Heavy gas cerenkov (pid)‏ • Scintillator (trigger)‏ • Kinematics • Forward angle region (8.5o– 16o) (electron and pion)‏ • Large angle region (16o– 25o) (electron only)‏ • High pressure polarized 3He target • 10 amags, 40 cm long, 60% polarization, spin flip • 11 GeV beam,15 µA (unpolarized/polarized) • 8 GeV • Polarized luminosity 1036/(cm2s)‏ • Unpolarized H/D/3He factorization test & dilution corrections

  17. GEMs: tracking device 6 GEMs in total: positioned inside magnet (momentum, angle and vertex reconstruction); Forward angle: 8.5o to 16o (5 layers of GEM)‏ Large angle: 16o to 25o to (4 layers GEM, 3 in common with Forward angle)‏ GEANT3 simulations show background rates in GEMs much less than the limit

  18. Particle identification • Electron identification • Forward angle: CO2 gas Cerenkov/EM calorimeter • 2 m long, 1 atm CO2,,,threshold for pion 4.8 GeV/c • Shower plus Cerenkov provides better than 104:1 for pion rejection for 1.5 to 4.8 GeV/c momentum region • 200:1 for pion rejection for momentum greater than 4.8 GeV/c (pion/e ratio < 1.5) • Multi-bounce mirror system for CO2 Cerenkov counter • Large angle • Electron momentum 4-6 GeV/c, expected pion/e ratio < 1.5 • ``Shashlyk''-type calorimeter, pion rejection 200:1, efficiency for electron detection 99%

  19. Electromagnetic Calorimeter Pion rejection factor 200:1 for E> 2.0 GeV

  20. Particle Pthreshold GeV/c n=1.03 Pthreshold GeV/c n=1.015  0.565 0.803 K 2.0 2.840 p 3.802 5.379 Pion identification Combination of 1 atm CO2 Cerenkov, a heavy gas Cerenkov, and an aerogel Cerenkov can reduce kaon Background to < 1%

  21. Kinematic coverage at 11 GeV

  22. Kinematic coverage at 8 and 11 GeV

  23. Azimuthal angular coverage • Full spin angle coverage with a solenoid detection system • Large coverage for Collins, Sivers and Pretzelosity angle • Important in disentangle all three terms • Symmetry in azimuthal angular acceptance can help reduce systematic uncertainties significantly With full azimuzhal coverage Simultaneously measured Better control of systematic error 1, 2 refer to two different Target spin directions in the lab

  24. Acceptance Incident beam energy 11 GeV

  25. Resolutions

  26. Rates Incident beam energy 11 GeV

  27. Projected results (ultimate precision in SSA)‏ 7 more bins in z Incident beam energy 11 GeV, 8 GeV projection and updates soon

  28. Positive pions Negative pions

  29. Power of SOLid

  30. Trigger and DAQ • Option 1: Single electron rate ~ 110 kHz • Electron trigger: ECAL + GC + SC • DAQ will use the CODA3 and the pipeline technique being developed for Hall D • Expect zero dead time with 100 – 200 kHz trigger rate. • Option 2: Coincidence rate ~ 90 kHz • Pion trigger: ECAL + Aerogel + SC • Multi-DAQs to reduce trigger rate in each DAQ. • Will introduce some dead time. Need further studies

  31. Sources Type Size Raw Asymmetry absolute 1.1 E-3 Background Subtraction relative 1.0% Nuclear Effects relative 4-6%? Diffractive Vector Meson relative 2-3% Radiative Correction relative 2% 3He Polarization relative 3% Total N/A 6.0-7.7%(relative)+1.1E-3(absolute)‏ Systematic Uncertainties Average Stat: 1.8e-3, Collins asymmetry ~2%

  32. Responsibilities • Aerogel Cerenkov detector: Duke, UIUC • CO2 gas Cerenkov detector: Temple U. • Heavy Gas Cerenkov Temple U. • ECal: W&M, UMass, JLab, Rutgers, Syracuse • GEM detectors:UVa, Miss State, W&M, Chinese Collaboration (CIAE, HuangshanU, PKU, LZU, Tsinghua, USTC), UKY, Korean Collaboration (Seoul National U) • Scintillator: Chinese Collaboration, Duke • Electronics: JLab • DAQ: LANL, UVa and JLab • Magnet: JLab and UMass • Simulation: JLab and Duke blue: common with PVDIS Black: part in common with PVDIS Red: This experiment only PAC decision: Defer with regret More simulations and studies underway to address the Concerns raised by the PAC

  33. Summary • The study of chiral-odd quark distribution function and fragmentation function: an exciting, rapidly developing frontier, surprising flavor dependence observed in Collins and Sivers function, Worldwide effort – Completed the 1st experiment atJLab • Future 11 GeV with Solenoid and polarized 3He target allows for a precision 3-d mapping of neutron Collins, Sivers, and pretzelocity asymmetries, and the extraction of transversity, Sivers and pretzlocity distribution functions. • Together with world proton results provides model independent determination of tensor charge of d quark. Provide benchmark test of Lattice QCD calculations • Supported by U.S. Department of Energy DE-FG02 03ER41231

  34. Transversity from JLab Hall A Linear accelerator provides continuous polarized electron beam Ebeam = 6 GeV Pbeam = 85% 3 experimental halls A C B 42

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