The first measurement of neutron Transversity using a transversely polarized 3 He target

Yi Qiang <[email protected]>Yi Qiang <[email protected]>

Yi QiangDuke University

for the Workshop on Hadron Physics in China and Opportunities with 12 GeV

JLabJuly 31, 2009

7/31/2009 1Neutron Transversity in Jefferson Lab Hall A


OutlineOverview of leading twist TMDsJefferson Lab Experiment E06-010

First neutron Transversity experiment

Experimental configurationPolarized 3He targetDetector performance

Future plan and impact



Nucleon Structure from DISUn-polarized Nucleon Structure Function

Longitudinal Momentum DistributionWell probed for 50 years over very large kinematics

rangeLongitudinal Polarized Nucleon Structure

FunctionsSince “spin crisis” in 1980s Plotted in fairly large range

Transversity: Can be probed in Semi-Inclusive DISNew business: recent measurements from HERMES

and COMPASS using Hydrogen and Deuteron targets

7/31/2009 Neutron Transversity in Jefferson Lab Hall A 3

f1 =

g1 =

h1 =


Blue: kT independent; Red: T-odd

Leading Twist TMDs


f1 =

f 1T =

g1 =

g1T =

h1 =

h1L =

h1T =

h1 =


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SL, ST: Target Polarization; e: Beam Polarization

Access Leading Twist Parton Distributions through Semi-Inclusive DIS


Unpolarized

PolarizedTarget

PolarizedBeam andTarget

Boer-Mulder

Sivers

Transversity

Pretzelosity


Transversity from JLab Hall A Linear accelerator

provides continuous polarized electron beamEbeam = 6 GeV

Pbeam = 85%

3 experimental halls


A B C


E06-010 CollaborationE06-010: Single Target-Spin Asymmetry in Semi-

Inclusive n↑(e, e’±) Reaction on a Transversely Polarized 3He Target

Spokespersons:Xiaodong Jiang (Rutgers/Los Alamos, Contact Person), Jian-ping Chen (JLab), Evaristo Cisbani (INFN-Rome), Haiyan Gao (Duke), Jen-Chieh Peng (UIUC)

Thesis Students:C. Dutta (Kentucky), J. Huang (MIT), A. Kalyan (Kentucky), J. Katich (W&M), X. Qian (Duke), Y. Wang (UIUC), Y. Zhang (Lanzhou U)

Approved with A rating and was just finished in early February, 2009.



Polarized3He Target

E06-010 Setup• Electron beam: E = 5.9

GeV• 40 cm polarized 3He

target• BigBite at 30 degrees as

electron arm:P = 0.7 ~ 1.8 GeV/c

• HRSL at 16 degrees as hadron arm:

P0 = 2.35 GeV/c

• Measure Collins, Sivers and pretzelosity asymmetries in valence range: x = 0.1 ~ 0.4


e

HRSL

16o

e’

BigBite30o


Rotate target spin direction to increase s coverage

Separation of Collins, Sivers and Pretzelosity effects through angular dependence


NN

NN

PA l

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SiversSivers

TransversityTransversity

PretzelosityPretzelosity

Vertical

Horizontal


Polarized 3He TargetEffective polarized neutron targetHigh luminosity: L(n) = 1036 cm-2 s-1

Fast spin exchange with K/Rb hybrid cells


~90% ~8% ~1.5%

Laser795 nm

25 G Holding Field

Oven230 oC

= 3”

40 cm

Target Chamber


Target Setup for TransversityNew vertical coil together with

existing horizontal coils and new oven allow 3He to be polarized in ALL three directions!


New narrow band COMET lasers make optical pumping more efficient.

3He spin pumped to horizontal and vertical directions.

Auto spin flip every 20 minutes.


NMR: Nuclear Magnetic ResonanceFree NMR at pumping chamber

from every auto spin flip.Target chamber polarization is

calibrated by Water NMR measurement.

EPR: Electron Paramagnetic ResonanceGot signal from both K and Rb.Measures pumping chamber

polarization.

3He Target Polarimetries


EPR

Water NMR


Online preliminary EPR/NMR analysis shows a stable 65% polarization with 15 A beam and 20 minute spin flip

Cell: AstralCell: Astral Cell: MaureenCell: Maureen

Target Performance



BigBite Spectrometer30 degrees to the beam rightDetect electronsA big bite of acceptance

64 msrP : 700 ~ 1800 MeV/c

3 Wire Chambers: 18 planesOptics is crucial for the

angular dependence separation and kinematics variables

Pre-Shower and Shower for electron PID



BigBite OpticsOptics for both negative and positive

charged particles have been done Wire Chamber Spatial Resolution: 180 mVertex Resolution: 1 cmAngular Resolution: < 10 mradMomentum Resolution: 1%


BigBite Sieve Slit


Electron Selection in BigBitePre-shower/Shower have been calibratedEnergy Resolution: 8%Well separated electrons and pions



Cherenkov Ring from RICH

Cherenkov Ring from RICH

4 Separation4 Separation

Left High Resolution Spectrometer16 degrees to beam left

with p0 = 2.35 GeV/cClean e/ separation with

Gas Cherenkov and Pion Rejector

Vertex and TOF coincidence with BigBite will help reduce the background

Kaon asymmetry data can also be extracted:A1: Pion rejection > 90 %RICH: K/ separation ~ 4 TOF: K/ separation ~ 4


e Coincidence Time

< 400 ps

K

p

K


Kinematics Coverage


y

Q2

W’

z

x

0.6 ~ 0.9

0.6 ~ 3 (GeV/c)2

1.5 ~ 2.3 (GeV/c2)

0.4 ~ 0.6

x<0.25

x>0.25

Sivers Angle: h-s Collins Angle: h+s Pretzelosity Angle: 3h-s

0 0.25 0.5


Projections of Collins and Sivers Functions



Projections of g1T First Neutron (3He) MeasurementWith Fast Beam Helicity Flip (30Hz)Projected Uncertainties (Stat. Only):

2.3% at low x3.4% at high x



Status of E06-010The experiment was smoothly

performed from Oct 2008 to Feb 2009.

Statistics exceeded the approved goal.

Detector calibrations and target analysis are ongoing.

Will start to extract physical asymmetries afterwards.



Future Plan and ImpactFinish all the data quality check, detector calibration

and target analysis by Sep 2009.Extract raw asymmetries: witness channel, blind

analysis and then raw physics asymmetry by Nov 2009.

Apply other corrections: dilution factor, background asymmetry correction, radiative correction and etc.

Final asymmetries separation: Collins, Sivers …The results from this experiment will provide

important constraints on the TMDs of u, d and s quarks in the valence quark region when combined with world data.

The experience obtained will greatly help us to plan the future SIDIS experiments.







E06-010 Collaboration Institutions

California State Univ., Duke Univ., Florida International. Univ., Univ. Illinois, JLab, Univ. Kentucky, LANL, Univ. Maryland, Univ. Massachusetts, MIT, Old Dominion Univ., Rutgers Univ., Temple Univ., Penn State Univ., Univ. Virginia, College of William & Mary, Univ. Sciences & Tech, China Inst. Of Atomic Energy, Beijing Univ., Seoul National Univ., Univ. Glasgow, INFN Roma and Univ. Bari, Univ. of Ljubljana, St. Mary’s Univ., Tel Aviv Univ.

Collaboration members A.Afanasev, K. Allada, J. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, F. Butaru, G. Cates, C. Chang, J.-P. Chen (Co-SP), W. Chen, S. Choi, C. Chudakov, E. Cisbani(Co-SP), E. Cusanno, R. De Leo, A. Deur, C. Dutta, D. Dutta, R. Feuerbach, S. Frullani, L. Gamberg, H. Gao(Co-SP), F. Garibaldi, S. Gilad, R. Gilman, C. Glashausser, J. Gomez, M. Grosse-Perdekamp, D. Higinbotham, T. Holmstrom, D. Howell, J. Huang, M. Iodice, D. Ireland, J. Jansen, C. de Jager, X. Jiang (Co-SP), Y. Jiang, M. Jones, R. Kaiser, A. Kalyan, A. Kelleher, J. Kellie, J. Kelly, A. Kolarkar, W. Korsch, K. Kramer, E. Kuchina, G. Kumbartzki, L. Lagamba, J. LeRose, R. Lindgren, K. Livingston, N. Liyanage, H. Lu, B. Ma, M. Magliozzi, N. Makins, P. Markowitz, Y. Mao, S. Marrone, W. Melnitchouk, Z.-E. Meziani, R. Michaels, P. Monaghan, S. Nanda, E. Nappi, A. Nathan, V. Nelyubin, B. Norum, K. Paschke, J. C. Peng(Co-SP), E. Piasetzky, M. Potokar, D. Protopopescu, X. Qian, Y. Qiang, B. Reitz, R. Ransome, G. Rosner, A. Saha, A. Sarty, B. Sawatzky, E. Schulte, S. Sirca, K. Slifer, P. Solvignon, V. Sulkosky, P. Ulmer, G. Urciuoli, K. Wang, Y. Wang, D. Watts, L. Weinstein, B. Wojtsekhowski, H. Yao, H. Ye, Q. Ye, Y. Ye, J. Yuan, X. Zhan, Y. Zhang, X. Zheng, S. Zhou.



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The first measurement of neutron Transversity using a transversely polarized 3 He target