Status Report:

JLAB Experiment E01-020 Hall A

(e,e’p) Studies of the Deuteron at High Q2

Luminita ComanFlorida International University

Spokespersons: W. Boeglin, M. Jones, P. Ulmer, E. Voutier

Ph.D. Students: Luminita Coman - Florida International University

Hassan Ibrahim - Old Dominion University - graduated

Content:

• Short introduction on (e,e’p) reaction• Kinematics and Cross Section review• Performed Optimizations/Calibrations• Applied cuts• Cross section results for E01020 experiment

• RTL response function results

• Summary

General Diagram of the 2H (e,e’p)n Reaction

High momentum q=(q0,q) is transferred to the deuteron nucleuspm = q-pf is the missing momentum

Kinematics

q=(,q) where = e-e’ and q=ki-kf

Pd=(MD,0)

Final state: Pf=(Ep,pf) and PR =(En,pn)

Q2= -q2 = q2-2 = 4e.e’sin2(e/2)

xBjorken variable: Q2/m.

momentum conservation: q + Pd = Pf + PR

x = 1 - Tn/mn -2Tn + q.pn/mn.

x>1 => PR||q <=> nq close to 00

x<1 => pR||-q <=> nq close to 1800

Theoretical CalculationGlauber Approximation

General Eikonal Approximation

• Shows that relativistic kinematics are important: The interaction is not instantaneous (the nucleons are at rest - GA)

R

Optimizations/Calibrations

• Detector calibrations done: optics, pointing,timing optimization

• Detector efficiency studies done:VDC efficiency for Q2 = 3.5 GeV/c2 data

Scintillator efficiencyCerenkov cut

• Luminosity studies done:Stable beam analysisReact_z dependence

VDC efficiency for Q2 = 3.5 GeV/c2 data

• Cut on multiplicity in the 4 wire planes:

Lmult_uv12>3. && Lmult_uv12<10.• Tracks cuts: Exactly one track• Eff = 1-track / (3-10) hits (in all planes)

Scintillator Efficiencies

Efficiency (%)

vs. Run number

Electron arm

Scintillator

Efficiency

S1 plane (blue)

S2 plane (red)

Determined Appropriate Cuts

• Cut on z difference : abs(z_diff)<0.015 m

• Cut on react_z : abs(react_z) < 0.05 m

• Fiducial cut -combined cut on E_miss, P_miss and Q^2

-10 <E_miss<15 MeV, dp_miss =20 MeV, dQ^2 =0.25 GeV/c^2

• A software rectangular cut was applied at the focal plane

• R function cut : R function was calculated for both experimental data and mceep and compared.

• Looked at the ratio between Rfn_exp to Rfn_mceep to determine in which range is linear

• R function cut : 0<rfn<0.03

R - function plotR function

Kin e20

Red -experimental

Blue - mceep

R - function plotR function

Kin f50

Red -experimental

Blue - mceep

R - function plotR function

Kin f10l

Red -experimental

Blue - mceep

R - function ratio experimental to

mceep R function

Kin d20

Experimental Cross Section Results

P_miss = 200 MeV/c

From right

to left kinematics d20, e20, f20l, g20,h20

Drawn with different

marker styles

Experimental Cross Section Results

P_miss = 400 MeV/c

From right

to left kinematics

e40, f40l,g40, i40,j40

Drawn with different

marker styles

Experimental Cross Section Results

P_miss = 500 MeV/c

From right

to left kinematics

d50, f50, g50,j50

Drawn with different

marker styles

Cross Section Results:

Experimental and Mceep (Laget) P_miss = 200 MeV/c

Mceep -blue

Experimental - red

Cross Section Results:

Experimental and Mceep (Laget) P_miss =

400 MeV/c

Mceep -blue

Experimental - red

Cross Section Results:

Experimental and Mceep (Laget) P_miss

500 MeV/c

Mceep -blue

Experimental - red

Summary

• Analysis of the RTL response functions finished • Publication under way/thesis defended (Hassan)• Mceep simulations done• Results for angular distribution of the experimental

cross sections close to final

Summary