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

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

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 E Charge and magnetism (current) distribution – Nucleon: Electric G E and magnetic G M form factor Spin distribution Quark momentum and flavor distribution Polarizabilities Strangeness content …..

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

Transversity Three twist-2 quark distributions: –Momentum distributions: q(x,Q 2 ) = q ↑ (x) + q ↓ (x) –Longitudinal spin distributions: Δq(x,Q 2 ) = q ↑ (x) - q ↓ (x) –Transversity distributions: δq(x,Q 2 ) = q ┴ (x) - q ┬ (x) Some characteristics of transversity: –δq(x) = Δq(x) for non-relativistic quarks –δq and gluons do not mix → Q 2 -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

Access Parton Distributions through Semi- Inclusive DIS Unpolarized Polarized Target Polarized Beam and Target S L, S T : Target Polarization; e : Beam Polarization Boer-Mulder Sivers Transversity Pretzelosity

Separation of Collins, Sivers and pretzelocity effects through angular dependence

A UT sin(  ) from transv. pol. H target Simultaneous fit to sin(  +  s ) and sin(  -  s ) `Collins‘ moments Non-zero Collins asymmetry Assume  q(x) from model, then H 1 _unfav ~ -H 1 _fav H 1 (BELLE) (arXiv:0805:2975) `Sivers‘ moments Sivers function nonzero (  + )  orbital angular momentum of quarks Regular flagmentation functions M. Anselmino et al, PRD75,05032(2007)

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

Sivers asymmetries from COMPASS deuteron

Collins asymmetries from COMPASS deuteron Phys. Lett. B 673 (2009)

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

e e’e’   HRS L BigBite 16 o 30 o Polarized 3 He Target Jefferson Lab E06-010: Single Target-Spin Asymmetry in Semi-Inclusive n ↑ (e, e’  ± ) Reaction on a Transversely Polarized 3 He 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 = Upgraded polarized 3 He target  20 min fast spin-flip  vertical polarization  improved performance BigBite for e and HRS L for  and K. BigBite detectors working well Commissioned RICH in HRS L

Nucleon Transversity at 11 GeV Using a Polarized 3 He 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

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

Experimental Overview SoLID (proposed for PVDIS) –GEMs (tracking+vertex), –Calorimeter (trigger/pid), –CO 2 gas cerenkov, aerogel (trigger/pid)‏ –Heavy gas cerenkov (pid)‏ –Scintillator (trigger)‏ –Kinematics Forward angle region (8.5 o – 16 o ) (electron and pion)‏ Large angle region (16 o – 25 o ) (electron only)‏ High pressure polarized 3 He target –10 amags, 40 cm long, 60% polarization, spin flip 11 GeV beam,15 µ A (unpolarized/polarized) –8 GeV Polarized luminosity /(cm 2 s)‏ Unpolarized H/D/ 3 He factorization test & dilution corrections

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

Particle identification Electron identification –Forward angle: CO 2 gas Cerenkov/EM calorimeter 2 m long, 1 atm CO 2,,, threshold for pion 4.8 GeV/c Shower plus Cerenkov provides better than 10 4 :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 CO 2 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%

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

Pion identification p K  P threshold GeV/c n=1.015 P threshold GeV/c n=1.03 Particle Combination of 1 atm CO 2 Cerenkov, a heavy gas Cerenkov, and an aerogel Cerenkov can reduce kaon Background to < 1%

Kinematic coverage at 11 GeV

Kinematic coverage at 8 and 11 GeV

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

Acceptance Incident beam energy 11 GeV

Resolutions

Rates Incident beam energy 11 GeV

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

Positive pions Negative pions

Power of SOLid

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

Systematic Uncertainties %(relative)+1.1E-3(absolute)‏N/ATotal 3%relative 3 He Polarization 2%relativeRadiative Correction 2-3%relativeDiffractive Vector Meson 4-6%?relativeNuclear Effects 1.0%relativeBackground Subtraction 1.1 E-3absoluteRaw Asymmetry SizeTypeSources Average Stat: 1.8e-3, Collins asymmetry ~2%

Responsibilities Aerogel Cerenkov detector: Duke, UIUC CO 2 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 PAC decision: Defer with regret More simulations and studies underway to address the Concerns raised by the PAC blue: common with PVDIS Black: part in common with PVDIS Red: This experiment only

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 1 st experiment at JLab Future 11 GeV with Solenoid and polarized 3 He 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

Transversity from JLab Hall A Linear accelerator provides continuous polarized electron beam –E beam = 6 GeV –P beam = 85% 3 experimental halls 42 A B C