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Experiment E (e,e'p) Studies of the Deuteron at High Q 2 P.E. Ulmer Old Dominion University Spokespersons: W. Boeglin, M. Jones, A. Klein, P. Ulmer and E. Voutier Postdoc: R. Roché Graduate Students: L. Coman and H. Ibrahim

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Outline Physics Motivation Some Analysis Results –VDC tracking –Target density studies –Beam position studies –Beam energy shifts Preliminary Physics Results

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Physics Motivation

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Physics Motivation Overview Elastic Quasielastic N*N* Deep Inelastic MECs/ICs (parallel kin) Wavefunction (parallel kin) R LT (relativity) (perpendicular kin) FSI (neutron angular distribution) Kinematics: Q 2 =0.8, 2.1, 3.5 GeV 2 P miss = MeV/c

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R LT and Relativity Relativistic current operator Longitudinal piece contains additional spin- orbit term Longitudinal piece contains additional spin- orbit term Can interfere with spin-flip magnetization term in transverse current Can interfere with spin-flip magnetization term in transverse current Non-relativistically, get no such contribution since L reflects charge only and can t interfere with spin-flip part of T: different final states Non-relativistically, get no such contribution since L reflects charge only and can t interfere with spin-flip part of T: different final states

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R LT (projected uncertainties)

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Final State Interactions

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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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Some Analysis Results

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Analysis Overview

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VDCs

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VDC U1 two-cluster intersection Spectrometer exit window z z = 0 z-inter cluster 1cluster 2

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z-coordinate of intersection of tracks for two clusters # Events z relative to each VDC plane (m) u1 v1 Exit window Left Arm

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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

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Event Display (R. Roché)

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Target Density

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LH 2 Boiling: 15 cm cigar cell Beam Current (μA) Events/charge (arb. Units) Cuts: -4<ε m <10 MeV 3 mult 7 clusters=1 Corrections: T5/E5 no VDC corr. Raster: 2mm x 2mm nominal, Fan: 60Hz 23.3% at 100 μA! PRELIMINARY

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LD 2 Boiling: ~9% variation / 100 uA 2mm x 2mm raster

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LD 2 Boiling: ~4% variation / 100 uA 4mm x 4mm raster

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Beam Position

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Beam Position (Reactz vs. BeamX for foil & raster) Left Arm Right Arm

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Reactz vs. BeamX BeamX Scaled by Factor of 1.3 Left Arm Right Arm

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Beam Energy

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Beam Energy Shifts 0.5 MeV 2 MeV Q 2 =0.8 GeV 2 Q 2 =2.1 GeV 2

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1 H(e,e'p) Missing Energy Using Arc Energy ( MeV)Using Tiefenbach Energy Emiss (MeV)

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Physics (Preliminary) Results

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Preliminary Results Q 2 = 2.1 (GeV/c) 2 Calculation J.M. Laget Q 2 = 3.5 (GeV/c) 2 nq FSI / PWIA

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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

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Credits Thanks to Werner Boeglin, Luminita Coman and Hassan Ibrahim for help with this talk.

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