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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