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E08-005: Ay0 in
Quasi-Elastic 3He(e,e’n) ScatteringElena LongHall A Collaboration MeetingDecember 17 t h , 2013
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
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Today’s Discussion◦ Brief background of the physics◦ Experimental method◦ Summary of past analysis◦ Summary of recent analysis◦ Results
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
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Simple 3He(e,e’n) - PWIA◦ Ideally, the only interaction that
occurs is when the incoming electron hits the neutron
◦ This model is called Plane Wave Impulse Approximation (PWIA)
◦ PWIA predicts the single-spin target asymmetry, Ay
0, to be exactly zero
12/17/2013
3He
Hall A Collaboration Meeting Elena Long <[email protected]>
=
�⃑�0= (𝐴𝑥0 , 𝐴𝑦
0 , 𝐴𝑧0 )
0 0
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3He(e,e’n) Complications◦ Since other nucleons exist in
the 3He nucleus, they cause secondary effects that must be taken into account
◦ These effects, particularly FSIs, cause Ay
0 to be non-zero
12/17/2013
◦ Final State Interactions (FSI)
◦ Meson Exchange Currents (MEC)
Hall A Collaboration Meeting Elena Long <[email protected]>
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Current Measurements◦Ay
0 data will test state-of-the-art calculations at high Q2
◦Neutron physics extracted from 3He (such as EM form factors) must correctly predict this asymmetry
◦Any non-zero result indicates higher order effects
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Hall A Collaboration MeetingElena Long <[email protected]> 6
0.6
0.4
0.2
0.0
0.0 0.2 0.4 0.6
Q2 (GeV/c)2
Ay0
Mod. PWIA [3]
PWIA
Historical Data and Models
[1] H.R. Poolman, Ph.D. Thesis, Vrije Universiteit, 1999.[2] J. Bermuth et al., Phys. Lett. B564, 199 (2003).[3] J.M. Laget, Phys. Lett. B273, 367 (1991).[4] J. Golak et al., Phys. Rev. C65, 044002 (2002).
12/17/2013
Q2 (GeV/c)2
0.6
0.4
0.2
0.0
0.0 0.2 0.4 0.6
Ay0
Faddeev Calculations at 0.16 (GeV/c)2 [1]
Mod. PWIA [1]
Mod. PWIA [1]
Mod. PWIA [3]
0.6
0.4
0.2
0.0
0.0 0.2 0.4 0.6
Q2 (GeV/c)2
Ay0 NIKHEF [1]
Faddeev Calculations at 0.16 (GeV/c)2 [1]
Mod. PWIA [1]
Mod. PWIA [1]
Mod. PWIA [3]
MAMI[2]
• Faddeev calculations by the Bochum group[4] correctly predicted FSI, where other groups expected a much lower value
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The Measurements
12/17/2013
Hall ALeft HRS
Right HRSBigBite
ARC
ComptonPolarimeter Raster
BCM eP
Møller Polarimeter
Polarized 3HeTarget
BPM
WireChambers
Trigger Plane(Scintillators)
HAND
PreshowerShower
VDCs
Q QQD
Scintillators
Gas Cerenkov
Pion Rejectors(Pb Glass)
BeamDump
D
Hall A Collaboration Meeting Elena Long <[email protected]>
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The Measurements3He(e,e’n) Channel
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
hIncident Polarized
Electron ScatteredElectron
θqγ*
q
-θe’
p pn
n
e
e
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The MeasurementsExperimental Set-up
• Run period was April-June 2009
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Right HRS
Polarized 3HeTarget
HAND
Standard Beamline
Target Pol.
Q2 (GeV/c)2
E0 (GeV)
RHRS (°)
RHRS P0 (GeV)
HAND(°)
Vertical 0.13 1.245 -17.0 1.1759 71.0Vertical 0.46 2.425 -17.0 2.1813 62.5Vertical 0.95 3.605 -17.0 3.0855 54.0
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The MeasurementsPolarized 3He Target
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Polarized 3HeTarget
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PumpingChamber
Target Chamber(Nuclear Physics Happens
Here)
The Measurements
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Polarized 3He Target• Optically pumped Rb and K vapor used to
polarized 3He via spin exchange (SEOP)
• NMR and EPR used to measure Pt
• N present in cell to absorb photons from spin-exchange
• Achieved Pt of
• Details in Y. Zhang, Ph.D. Thesis, Rutgers, 2013
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The MeasurementsRight HRS
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Right HRS
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The MeasurementsRight HRS• Detected scattered electrons
from 3He(e,e’n) and 3He(e,e’)
• Provided trigger for HAND
• Detector package included VDCs, trigger scintillators, gas Cherenkov, and lead-glass calorimeters
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Right HRS
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The MeasurementsRight HRS• Detected scattered electrons
from 3He(e,e’n) and 3He(e,e’)
• Provided trigger for HAND
• Detector package included VDCs, trigger scintillators, gas Cherenkov, and lead-glass calorimeters
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Right HRS
Hall A Collaboration MeetingElena Long <[email protected]> 15
The Measurements
12/17/2013
x sieve
(m
)
-0.04 0.00 0.04-0.10
-0.05
0.00
0.05
0.10
0
2
4
6
8
10
12
14
16
18
20
ysieve (m)
Right HRS• Details in G. Jin, Ph.D. Thesis,
University of Virginia, 2011
Hall A Collaboration MeetingElena Long <[email protected]> 16
The Measurements
12/17/2013
Preshower/Shower
Right HRS• Electron ID
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
Hall A Collaboration MeetingElena Long <[email protected]> 17
The Measurements
12/17/2013
Right HRS• Electron ID
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
Bjorken x
Hall A Collaboration MeetingElena Long <[email protected]> 18
The Measurements
12/17/2013
Right HRS• 3He(e,e’) Single-Spin
Asymmetry
• Comparison with Y. Zhang
3He(e,e’) SSA – Before Charge/LT Corrections
χ2/dof=2.13
Preliminary
Hall A Collaboration MeetingElena Long <[email protected]> 19
The Measurements
12/17/2013
Right HRS• 3He(e,e’) Single-Spin
Asymmetry
• Comparison with Y. Zhang
3He(e,e’) SSA – After Charge/LT Corrections
χ2/dof=1.95
Preliminary
Hall A Collaboration MeetingElena Long <[email protected]> 20
The Measurements
12/17/2013
Right HRS• 3He(e,e’) Single-Spin
Asymmetry
• Comparison with Y. Zhang
Q2=0.1 (GeV/c)2
Q2=0.5 (GeV/c)2 Q2=1.0 (GeV/c)2
χ2/dof=1.95
χ2/dof=0.70 χ2/dof=1.29
Preliminary Preliminary
Preliminary
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The MeasurementsHall A Neutron Detector (HAND)
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
HAND
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The MeasurementsHall A Neutron Detector (HAND)
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
HAND
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The MeasurementsHall A Neutron Detector (HAND)• Plastic scintillator array
• Detected neutrons from 3He(e,e’n) in coincidence with the RHRS
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
2 x 11 x 70 cm3
10 x 10 x 100 cm3
10 x 12.5 x 100 cm3
10 x 15 x 100 cm3
10 x 25 x 100 cm3
Hall A Collaboration Meeting Elena Long <[email protected]>
Front ViewSide View
...
100 cm
Stacking ofscintillator bars
in a plane
n = 30 (plane 1)24 (plane 2)22 (plane 3)12 (plane 4)
Scintillator
LightGuide
12…
…
n
PMT
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The MeasurementsHall A Neutron Detector (HAND)• Plastic scintillator array
• Detected neutrons from 3He(e,e’n) in coincidence with the RHRS
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
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The MeasurementsHall A Neutron Detector (HAND)• Neutrons detected using
veto method
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
p
Hall A Collaboration Meeting Elena Long <[email protected]>
26
The MeasurementsHall A Neutron Detector (HAND)• Neutrons detected using
veto method
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
n
Hall A Collaboration Meeting Elena Long <[email protected]>
27
pp
p
p
p
p
p
p
p
pp
p
pp
p
p
p
p
pp
p
p
pp
p
p
pp
p
p
p p
p
pp
p
p
The MeasurementsHall A Neutron Detector (HAND)• Neutrons detected using
veto method
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
n
Hall A Collaboration Meeting Elena Long <[email protected]>
p
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The MeasurementsHall A Neutron Detector (HAND)• Neutrons detected using
veto method
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
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The MeasurementsHall A Neutron Detector (HAND)• Time-of-Flight background
subtracted from the neutron peak
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Q2 = 0.1 ToF Background
Q2 = 0.5 & 1.0 ToF Background
Neutrons
Neutrons
Hall A Collaboration MeetingElena Long <[email protected]> 30
The Measurements
Proton Contamination• To find misidentified protons, apply neutron cuts to H(e,e’p)
• Find ratio of protons:neutrons from 3He(e,e’n) and 3He(e,e’p)Hall A Neutron Detector
(HAND)• Proton contamination
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
Hall A Collaboration MeetingElena Long <[email protected]> 31
The Measurements
Proton Contamination• Using and total measured He events in HRS, find expected number of protons and neutrons thrown at HAND
• Include to estimate number of misidentified protons in 3He
• Calculate proton dilution factor
Hall A Neutron Detector (HAND)• Proton contamination
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
Use to find efficiency,
33
Results• Run-by-run Ay
0
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Q2=0.1 (GeV/c)2
Q2=0.5 (GeV/c)2 Q2=1.0 (GeV/c)2
χ2/dof=0.517
χ2/dof=2.89 χ2/dof=10.30
𝛿 𝐴𝑦0=𝑆 𝛿 𝐴𝑦
0 ′
𝛿 𝐴𝑦0 ′=𝜀𝑠𝑡𝑎𝑡+𝜀𝑠𝑦𝑠 ′
𝑆=⌈ χ2
𝑑𝑜𝑓 ⌉1 /2
𝜀𝑠𝑦𝑠=𝑆𝜀𝑠𝑦𝑠 ′+(S −1)𝜀𝑠𝑡𝑎𝑡𝛿 𝐴𝑦
0=𝜀𝑠𝑡𝑎𝑡+𝜀 𝑠𝑦𝑠
Preliminary Preliminary
Preliminary
34
Results• Run-by-run Ay
0
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Q2=0.1 (GeV/c)2
Q2=0.5 (GeV/c)2 Q2=1.0 (GeV/c)2
χ2/dof=0.517
χ2/dof=1.0 χ2/dof=1.0
𝛿 𝐴𝑦0=𝑆 𝛿 𝐴𝑦
0 ′
𝛿 𝐴𝑦0 ′=𝜀𝑠𝑡𝑎𝑡+𝜀𝑠𝑦𝑠 ′
𝑆=⌈ χ2
𝑑𝑜𝑓 ⌉1 /2
𝜀𝑠𝑦𝑠=𝑆𝜀𝑠𝑦𝑠 ′+(S −1)𝜀𝑠𝑡𝑎𝑡𝛿 𝐴𝑦
0=𝜀𝑠𝑡𝑎𝑡+𝜀 𝑠𝑦𝑠
Preliminary Preliminary
Preliminary
Hall A Collaboration MeetingElena Long <[email protected]> 35
Results• Systematic Uncertainties
12/17/2013
Hall A Collaboration MeetingElena Long <[email protected]> 36
Results• Ay
0 vs. ν
12/17/2013
Preliminary Preliminary
Preliminary
Hall A Collaboration MeetingElena Long <[email protected]> 37
Results• Ay
0 vs. Q2
• Linear
12/17/2013
Preliminary
Hall A Collaboration MeetingElena Long <[email protected]> 38
Results• Ay
0 vs. Q2
• Logarithmic
12/17/2013
Preliminary
39Hall A Collaboration MeetingElena Long <[email protected]>
Thank you!
12/17/2013
Graduate Students
Spokespersons
Run Coordinators
Advisors
Hall A Collaboration MeetingElena Long <[email protected]> 42
The Measurements
1]G. Jin, Ph.D. Thesis, University of Virginia, 2011.
12/17/2013
Right HRS• Electron ID
Reaction Point in z
Hall A Collaboration MeetingElena Long <[email protected]> 43
The Measurements
12/17/2013
Right HRS• Electron ID
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
Cerenkov
Hall A Collaboration MeetingElena Long <[email protected]> 44
The Measurements
1]G. Jin, Ph.D. Thesis, University of Virginia, 2011.
12/17/2013
Right HRS• Electron ID
Preshower/Shower
Hall A Collaboration MeetingElena Long <[email protected]> 45
The Measurements
1]G. Jin, Ph.D. Thesis, University of Virginia, 2011.
12/17/2013
Right HRS• Electron ID
Theta/Phi
46
Simple 3He(e,e’n) - PWIA◦ Ideally, the only interaction that
occurs is when the incoming electron hits the neutron
◦ This model is called Plane Wave Impulse Approximation (PWIA)
◦ PWIA predicts the single-spin target asymmetry, Ay
0, to be exactly zero
12/17/2013
3He
Hall A Collaboration Meeting Elena Long <[email protected]>
Hall A Collaboration MeetingElena Long <[email protected]> 47
TheMeasurements
• To find misidentified protons, apply neutron cuts to H(e,e’p)
• Find ratio of protons:neutrons from 3He(e,e’n) and 3He(e,e’p)
• Using and total measured He events in HRS, find expected number of protons and neutrons thrown at HAND
• Include to estimate number of misidentified protons in 3He
• Use to calculate proton dilution factor
Hall A Neutron Detector (HAND)• Proton contamination
• Details in E. Long, Ph.D. Thesis, Kent State University, 2012 (arXiv:1209.2739)
12/17/2013
Use to find efficiency,
48
The MeasurementsReference Slide• Lorem ipsum dolor sit amet,
consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
12/17/2013 Hall A Collaboration Meeting Elena Long <[email protected]>
Hall A Collaboration MeetingElena Long <[email protected]> 49
Results• Ay
0 vs. Q2
• Linear and Logarithmic
12/17/2013