Jin Huang PhD Candidate, MIT For MENU 2010 May 31, 2010 @ Williamsburg.

Measurement ofDouble Spin Asymmetry ALT

in Deep Inelastic Pion Electroproduction on a Transversely

Polarized 3He Target

Jin HuangPhD Candidate, MIT

For MENU 2010May 31, 2010 @ Williamsburg

Jin Huang <[email protected]> 2

Un-polarized Nucleon Structure Function◦ Longitudinal Momentum Distribution◦ Well probed for 50 years over very large kinematic range

Longitudinal Polarized Nucleon Structure Functions◦ Since “spin crisis” in 1980s ◦ Plotted in fairly large range

Transverse Momentum Dependent (TMD) Partonic Distributions◦ Sensitive to the transverse structure of the nucleon◦ Accessible through Semi-Inclusive DIS (SIDIS)◦ A new phase of study

MENU 2010

Nucleon Structure from Deep Inelastic Scattering (DIS)

g1 =

f1 =

Leading-Twist TMDsQuark polarization

Un-Polarized Longitudinally Polarized

Transversely Polarized

Nucleon Polarization

U

L

T f 1T = g1T

=

h1L =

h1 =

h1T =

h1T =

Transversity

Boer-Mulder

PretzelositySivers

Helicity

Nucleon SpinQuark Spin

f1 =

g1 =

: See X. Jiang’s Talk on Thu : This Talk

Jin Huang <[email protected]> 4MENU 2010

Access TMDs through SIDIS

...]})cos(1[

...]1[

...])3sin(

...)()sin(

)sin([

...])2sin([

...)2cos(

...{

)1(2

)cos(2

2

)3sin(

)sin(

)sin(

)2sin(

)2cos(

,

2

2

2

2

Sh

Sh

Sh

Sh

h

h

LTSheT

LLeL

UTSh

ULSh

UTShT

ULhL

UUh

TUU

hhS

FS

FS

F

F

FS

FS

F

F

y

xyQdPdzddxdyd

d

Unpolarized

PolarizedTarget

PolarizedBeam andTarget

Boer-Mulder

Sivers

Transversity

Pretzelosity

f1 =

f 1T =

g1 =

g1T =

h1 =

h1L =

h1T =

h1T =

SL, ST: Target Polarization; le: Beam Polarization


g1T DF describe quark longitudinal polarization in a transversely polarized nucleon

Such polarization can be non-vanishing only if the Orbital Angular Momentum is non-zero

Extractable fromDouble Beam-Target spin asymmetry in SIDIS with transversely polarized target: ALT

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g1T Distribution Function

hq

qTLT

hs

shhs

DgF

ddd

dddA

sh

sh

11)cos(

)cos(LT

)cos(2

C

CTo leading twist:


pT weighted could be estimated from data of g1 DF through Lorentz Invariance Relations and Wandzura and Wilczek Relations

Ref to A. Kotzinian and P. J. Mulders, Phys. Rev. D 54, 1229 (1996)

With assumption of pT dependence, then ALT

could also be estimated

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One Prediction of g1T and ALT

)1(1qTg

From A. Kotzinian, B. Parsamyan, and A. Prokudin, Physical Review D 73 114017 (2006)

xf

xgq

q

qT

)1(1

)cos(LT

shA


No SIDIS ALT Measurement until recent years COMPASS data

◦ ALT on Deuteron (~= Neutron + Proton)

◦ ALT Mixed with Single Target Spin Asymmetriesin COMPASSextra uncertainty

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Existing Results

Eur. Phys. J. Special Topics 162, 89–96 (2008)


Jefferson Lab Hall A Newport News,

Virginia Linear accelerator

provides continuous polarized electron beam◦ Ebeam = 6 GeV

◦ Pbeam = 85%

3 experimental hallsA B C


E06‑010 Experiment Setup Polarized 3He Target Polarized Electron Beam

◦ ~80% Polarization◦ Fast Flipping at 30Hz◦ PPM Level Charge Asymmetry

controlled by online feed back BigBite at 30º as Electron

Arm◦ Pe = 0.7 ~ 2.2 GeV/c

HRSL at 16º as Hadron Arm◦ Ph = 2.35 GeV/c

Beam Polarimetry(Møller + Compton)

LuminosityMonitor


Polarized Electron Beam

Møller Polarimetry Compton Polarimetry

Performed per week Polarization -> ~80%

Polarization monitoring Calibrated by Møller

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BeamPolarimetry

LuminosityMonitor

Ch

ristm

as

Dow

nti

me

http://www.jlab.org/~moller/E06‑010.html

Preliminary


New narrow bandwidth COMET lasers Fast spin exchange with K/Rb hybrid cells

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Polarized 3He TargetBeamPolarimetry

LuminosityMonitor

Beam

3HeCell

~90% ~1.5 ~8%

S S’ D


High luminosity: L(n) = 1036 cm-2 s-1

Record high 65% polarization (preliminary) in beam with automatic spin flip / 20min

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Performance of 3He TargetBeamPolarimetry

LuminosityMonitor


Single Dipole Magnet Detects electrons A “big bite” of acceptance

◦ = DW 64 msr◦ P : 0.7 ~ 2.2 GeV/c

3 Wire Chambers: 18 planes for precise tracking

Bipolar momentum reconstruction

Pre-Shower and Shower for electron PID

Scintillator for coincidence with Left HRS

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BigBite Spectrometer

Pre-ShowerShower

Scintillators3 Multi-wireDrift Chambers

(18 planes)

BeamPolarimetry

LuminosityMonitor


Left HRS to detect hadrons of ph = 2.35 GeV/c

QQDQ magnet configuration◦ Very high momentum resolution

Vertical Drift Chambers◦ Tracking

Scintillator trigger planes◦ 340ps Coinc. Timing Resolution

Gas Cherenkov & Lead-glass blocks◦ e/hadron separation

Aerogel Cherenkov &RICH detector◦ π/K separation

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High Resolution Spectrometer

BeamPolarimetry

LuminosityMonitor

Detector Hut

D1Q1 Q2 Q3

DetectorPackage


Data Coverage

pT & ϕh- ϕS Coverage

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Kinematics Coverage

x bin 1 x bin 2

x bin 3 x bin 4

Q2>1GeV2

W>2.3GeV

z=0.4~0.6

W’>1.6GeV

x bin 1 2 3 4


7 PhD Students◦ 3 Graduated this month

Detector calibration done Target analysis close to finalization Extensive data quality checks

◦ Run selection/beam trip cut/yield check/witness channel check

Two analysis teams cross check results◦ Red Team: Maximum Likelihood Method◦ Blue Team: Local Pair-Angular Bin-Fit Method◦ Asymmetry results are consistent

Systematics in progress Active theory supports

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Analysis Progress

√


Preliminary 3He ALT

◦ Systematic uncertainty is still under work◦ Projected neutron ALT stat. uncertainty : 6~10%

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Preliminary Asymmetry Result

Preliminary Systematic Uncertainty


First measurement of neutron ALT from polarized 3He target

Systematic uncertainties is improved by fast beam helicity flip

Data will cover valence range Promising Kaon ALT data Submitting first paper in few months Precision 4D mapping planed after Jefferson

Lab 12GeV upgrade

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Conclusion


Backup SlidesSystematics Table

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Item Systematic Uncertainty

N2 dilution 0.3~0.6% Relative

Yield Drift PPM Relative

MLE Non-local <100PPM Absolute Raw

MLE Approximation 125PPM Absolute Raw

BigBite π− Cont. 1~7% of Stat. Uncertainty

BigBite Photon-induced electron Cont. ~80%, 40%, 10%, 10% of Stat. Uncertainty

Random Coincidence Correction 10e-4 Absolute Raw

HRS Kaon Cont. 1.4e-4 Absolute Raw

Bin Centering ~10%, 6%, 10%, 20% of Stat. Uncertainty

Target Density 7PPM Absolute Raw

Target Polarization 5% Relative

Beam Polarization 3.8% Relative + 3.7% Rel.

Left HRS Single Track <5e-5 Absolute Raw

BigBite Tracking Quality ~1e-4 for Pi-; <5e-5 for Pi+ Absolute Raw

Livetime/Charge Asymmetry Correction MLE only: <10 PPM level Absolute Raw

A_LL leak 10~20% for Pi+ 5% for Pi- (Rel. to Stat. Uncer.)

MENU 2010

Table of Systematics

Jin Huang PhD Candidate, MIT For MENU 2010 May 31, 2010 @ Williamsburg.

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