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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(
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)sin([
...])2sin([
...)2cos(
...{
)1(2
)cos(2
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)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
Jin Huang <[email protected]> 5
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
MENU 2010
g1T Distribution Function
hq
qTLT
hs
shhs
DgF
ddd
dddA
sh
sh
11)cos(
)cos(LT
)cos(2
C
CTo leading twist:
Jin Huang <[email protected]> 6
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
MENU 2010
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
Jin Huang <[email protected]> 7
No SIDIS ALT Measurement until recent years COMPASS data
◦ ALT on Deuteron (~= Neutron + Proton)
◦ ALT Mixed with Single Target Spin Asymmetriesin COMPASSextra uncertainty
MENU 2010
Existing Results
Eur. Phys. J. Special Topics 162, 89–96 (2008)
Jin Huang <[email protected]> 8MENU 2010
Jefferson Lab Hall A Newport News,
Virginia Linear accelerator
provides continuous polarized electron beam◦ Ebeam = 6 GeV
◦ Pbeam = 85%
3 experimental hallsA B C
Jin Huang <[email protected]> 9MENU 2010
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
Jin Huang <[email protected]> 10
Polarized Electron Beam
Møller Polarimetry Compton Polarimetry
Performed per week Polarization -> ~80%
Polarization monitoring Calibrated by Møller
MENU 2010
BeamPolarimetry
LuminosityMonitor
Ch
ristm
as
Dow
nti
me
http://www.jlab.org/~moller/E06‑010.html
Preliminary
Jin Huang <[email protected]> 11
New narrow bandwidth COMET lasers Fast spin exchange with K/Rb hybrid cells
MENU 2010
Polarized 3He TargetBeamPolarimetry
LuminosityMonitor
Beam
3HeCell
~90% ~1.5 ~8%
S S’ D
Jin Huang <[email protected]> 12
High luminosity: L(n) = 1036 cm-2 s-1
Record high 65% polarization (preliminary) in beam with automatic spin flip / 20min
MENU 2010
Performance of 3He TargetBeamPolarimetry
LuminosityMonitor
Jin Huang <[email protected]> 13
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
MENU 2010
BigBite Spectrometer
Pre-ShowerShower
Scintillators3 Multi-wireDrift Chambers
(18 planes)
BeamPolarimetry
LuminosityMonitor
Jin Huang <[email protected]> 14
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
MENU 2010
High Resolution Spectrometer
BeamPolarimetry
LuminosityMonitor
Detector Hut
D1Q1 Q2 Q3
DetectorPackage
Jin Huang <[email protected]> 15
Data Coverage
pT & ϕh- ϕS Coverage
MENU 2010
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
Jin Huang <[email protected]> 16
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
MENU 2010
Analysis Progress
√
Jin Huang <[email protected]> 17
Preliminary 3He ALT
◦ Systematic uncertainty is still under work◦ Projected neutron ALT stat. uncertainty : 6~10%
MENU 2010
Preliminary Asymmetry Result
Preliminary Systematic Uncertainty
Jin Huang <[email protected]> 18
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
MENU 2010
Conclusion
Jin Huang <[email protected]> 20
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