Experiment E01-020 (e,e'p) Studies of the Deuteron at High Q 2 P.E. Ulmer Old Dominion University...
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Transcript of Experiment E01-020 (e,e'p) Studies of the Deuteron at High Q 2 P.E. Ulmer Old Dominion University...
Experiment E01-020(e,e'p) Studies of the Deuteron at High Q2
P.E. Ulmer
Old Dominion University
Spokespersons: W. Boeglin, M. Jones, A. Klein, P. Ulmer and E. VoutierPostdoc: R. RochéGraduate Students: L. Coman and H. Ibrahim
Outline
• Physics Motivation
• Some Analysis Results– VDC tracking– Target density studies– Beam position studies– Beam energy shifts
• Preliminary Physics Results
Physics Motivation
Physics Motivation Overview
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d2σ
dωdΩElastic
Quasielastic
N*
Deep Inelastic
MECs/ICs (parallel kin)
Wavefunction (parallel kin)
RLT (relativity)(perpendicular kin)
FSI(neutron angular distribution)
Kinematics: Q2=0.8, 2.1, 3.5 GeV2
Pmiss = 0-500 MeV/c
RLT and Relativity
Relativistic current operatorRelativistic current operator
• Longitudinal piece contains additional Longitudinal piece contains additional spin- orbit termspin- orbit term• Can interfere with spin-flip Can interfere with spin-flip magnetization term in transverse magnetization term in transverse currentcurrent• Non-relativistically, get no such Non-relativistically, get no such contribution since contribution since L L reflects charge only reflects charge only and can’t interfere with spin-flip part of and can’t interfere with spin-flip part of TT: different final states: different final states
RLT (projected uncertainties)
Final State Interactions
Eikonal Approximation
• FSI described as sequential multiple scatterings• , b impact parameter • successfully used in hadron scattering• for nucleons at rest Glauber approximation• for moving nucleons Generalized Eikonal
Approximation (GEA, Sargsian), Generalized Glauber Approximation (GGA, Ciofi degli Atti), Relativistic Multiple Scattering Glauber Approximation (RMSGA, Ryckebusch)
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l→ db∫∑
Some Analysis Results
Analysis Overview
VDCs
VDC U1 two-cluster intersection
Spectrometer exit window
z
z = 0
z-inter
cluster 1 cluster 2
z-coordinate of intersection of tracks for two clusters#
Eve
nts
z relative to each VDC plane (m)
u1
v1
Exit window
Left Arm
Transverse dimension: Left Arm
Y for 2 cluster intersection (using u1 and v1) (meters)
-8.6 cm +9.2 cm
Positions taken from Gaussian fits
(not shown).
Distance between peaks: 17.8 cm
Width of exit window: 17.1 cm
Event Display (R. Roché)
Target Density
LH2 Boiling: 15 cm cigar cell
Beam Current (μA)
Ev
ents
/ch
arg
e (a
rb. U
nit
s)
Cuts:
-4<εm<10 MeV
3mult7 clusters=1
Corrections:
T5/E5
no VDC corr.
Raster: 2mm x 2mm nominal, Fan: 60Hz
23.3% at 100 μA!
PRELIMINARY
LD2 Boiling: ~9% variation / 100 uA 2mm x 2mm raster
LD2 Boiling: ~4% variation / 100 uA4mm x 4mm raster
Beam Position
Beam Position(Reactz vs. BeamX for foil & raster)
Left Arm Right Arm
Reactz vs. BeamX BeamX Scaled by Factor of 1.3
Left Arm Right Arm
Beam Energy
Beam Energy Shifts
0.5 MeV
2 MeV
Q2=0.8 GeV2 Q2=2.1 GeV2
1H(e,e'p) Missing Energy
Using Arc Energy (2843.6 MeV) Using Tiefenbach Energy
Emiss (MeV) Emiss (MeV)
Physics (Preliminary) Results
Preliminary Results
Q2 = 2.1 (GeV/c)2
Calculation J.M. Laget
Q2 = 3.5 (GeV/c)2
nq nq
FS
I/P
WIA
FS
I/P
WIA
Summary• Lessons learned
– Always use hardware collimators in HRS– Never use cigar cell targets– Watch beam energy carefully
• Main hurdles ahead– VDC tracking efficiency– Target boiling studies– Absolute normalizations
• Status– First post-running analysis pass nearly complete– Expect preliminary cross sections in few months
Credits
Thanks to Werner Boeglin, Luminita Coman and Hassan Ibrahim for help with this talk.