4He(e,e'p)X, April 13 and April 14, 2011, 16 hoursMeasured Pmiss at 0.153 to 1.0 GeV/c, xb = 1.24, Q2 = 2

(GeV/c)2

• Extension of SRC 2 body data which measured Pmiss from 0.4 to 1 GeV/c

• Actual target thickness(20 cm), 20 K at 10 atm = 1x1023/cm3

• Target thickness from proposal(10cm) 6 K at 10 atm = 1.24x1023/cm3

Students: S. Iqbal(CSULA), N. McMahon(CNU)Spokespersons: A. Saha, D. Higinbotham, F. Benmokhtar, S. Gilad, K. AniolHall A Collaboration Experiment

1

Motivation – Cross sections for 4He(e,e'p)3H, xb=1.25

and Nucleon Correlations4He is fundamental for nuclear microscopic theory. Theory must include many body forces for the 4 body system.

First measurement of 4He(e,e'p)X at this value of xb >1.

Theory should be able to account for all the nucleon channels.X = 3H, n+2H, n+n+p

Compare to theoretical cross sections (4He(e,e'p)3H, xb=1.25)

Compare to F. Benmokhtar results at 3He(e,e'p)X (xb =1) for 2 body

absorption peak in continuum.

2

755 MeV/c

625 MeV/c

500 MeV/c

380 MeV/c

150 MeV/c

800 MeV/cUnder analysis

0.153 GeV/c

0.353 GeV/c

0.500 GeV/c

0.625 GeV/c

0.755 GeV/c

0.800 GeV/c

4He(e,e'p)XMissing Energy

For central kinematics

triton

2 body absorption

Steps in the Analysis for 4He(e,e'p)3H

We have overlapping missing momentum bins for 0.153 and 0.353 GeV/c kinematic settings

Divide missing momentum into 50 MeV/c bins in data

Divide missing momentum into 50 MeV/c bins in simulation

Compare data from two kinematic settings using simulation

Efficiencies TBD e.g. dead time, acceptances, target density and beam heating effects, match (w,q) cuts

4

Preliminary triton yields/electron - Simulation assumes uniform illumination of spectrometer apertures.Have received theory RDWA from MadridNext step to include theory in simulation.

5

Emiss (MeV)

F. Benmokhtar, et al. E89044Phys.Rev.Lett.94:082305,2005

3He(e,e'p)X, Q2=1.55 GeV2, xb = 1

Similar 2 body absorption seen in 3He – needs 3bbu to fit cross section

Next StepsGet experimental cross sections• Get more theory calculations for 2 body.We have Madrid’scalculations now

• Need theory for 3 body. We have promises.

• Extract the Effective Density and compare to 3He.

See if there is scaling!

4He(e,e'p)X xb = 1.25, Q2 = 2 (GeV/c)2

0.755 GeV/c

0.625 GeV/c

0.500 GeV/c

0.353 GeV/c

0.153 GeV/c

LE

miss

Extra Slides for backup

Semi-Inclusive A(e,e’p)Xprobes a p-n pair?

-Pm

p = q-Pm

q,

Pm

e

e’

3He(e,e'p)X, Q2=1.55 GeV2, xb = 1 Jlab-E89044 Hall A experiment.

Example:

Missing Energy

Effective Density Distribution 3He(e,e'p)X, Q2=1.55 GeV2, xb = 1

-J. M. Laget Calculations (Fadeev WF and Paris Potential ( diagramatic approach)-Also available are calculations from C. degli-Atti et al., using realistic wave function with generalized Eikonal approximation for FSI.

-Conclusions: Both Correlations in initial state and Final State Interactions play a role in this strength .