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.