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presented by Werner Boeglin Florida International University Miami

Deuteron Electro-Disintegration at Very High Missing Momenta PR10-003 Hall C Collaboration Experiment. presented by Werner Boeglin Florida International University Miami. Why the Deuteron. only bound two-nucleon system fundamental system in nuclear physics

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presented by Werner Boeglin Florida International University Miami

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  1. Deuteron Electro-Disintegration at Very High Missing MomentaPR10-003Hall C Collaboration Experiment presented by Werner Boeglin Florida International University Miami

  2. Why the Deuteron • only bound two-nucleon system • fundamental system in nuclear physics • testing ground for any model of the NN interaction • hope to find new phenomena at short distances • prototype short range correlation (SRC)

  3. Challenges • Reaction dynamics: • photon interacts with a deeply bound nucleon • what is the EM current structure • Final State Interactions • high Q2 : eikonal approximations • Deuteron wave function • probe NN wave function at small distances • search for manifestations of new degrees of freedom All these problems are interconnected New data are necessary !

  4. Aim of Experiment • Determine cross sections at missing momenta up to 1 GeV/c • Measure at well defined kinematic settings • Selected kinematics to minimize contributions from FSI • Selected kinematics to minimize effects of delta excitation Why ? • Explore a new kinematical region of the 2-nucleon system • Practically no data exist so far • SRC studies cover similar region on missing momenta e.g. experiment E07-006 need deuteron data for interpretation

  5. From proposal PR07-006 unexplored 1 GeV/c

  6. D(e,e’p) Reaction Mechanisms reduced at certainkinematics ? expected to be small at large Q2 supressed for x>1

  7. Experiments at low(er) Q2 IC+MEC large FSI FSI included JLAB Q2 = 0.67 (GeV/c)2 Ulmer et al. MAMI Q2 = 0.33 (GeV/c)2Blomqvist et al.

  8. Eikonal Approximation successfully describes D(e,e’p)n at high Q2 • FSI described as sequential (soft) scatterings • successfully used in hadron scattering • for nucleons at rest  Glauber approximation • for moving nucleons  Generalized Eikonal Approximation • angle between q and outgoing nucleon small (< 10o)

  9. Calculations Compared to Experiment Data: Egyian et al. (CLAS) PRL 98 (2007) pm = 250 ± 50 MeV/c pm = 500 ± 100 MeV/c Calculation. Sargsian

  10. Momentum Dependence from CLAS cross sections averagedover CLAS acceptance !

  11. Selection of Kinematics minimize FSI pm = 500 MeV/c pm = 400 MeV/c pm = 200 MeV/c pm bin width : ± 20 MeV/c

  12. Angular Distributions up to pm = 1GeV/c FSI depend weakly on pm Calculation: M.Sargsian

  13. FSI Reduction • b determined by nucleon size • cancellation due to imaginary rescattering amplitude • valid only for high energy (GEA)

  14. FSI contribution estimates M.Sargsian (GEA)

  15. Measurements in Hall C Beam: Energy: 11 GeV Current: 80mA Electron arm fixed at: SHMS at pcen = 9.32 GeV/c qe = 11.68o Q2 = 4.25 (GeV/c)2 x = 1.35 Vary proton arm to measure : pm = 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 GeV/c HMS 1.96 ≤ pcen ≤ 2.3 geV/c Angles: 63.5o ≥qp ≥53.1 Target: 15 cm LHD

  16. Kinematic configurations direct reactionproton is hit indirect reactionneutron is hit pn>1.9 GeV/cstrongly suppressed

  17. Estimated Counts per Setting Estimate using SIMC and PWIA Dpm=40 MeV/c, cut on acceptance > 20%

  18. Accidentals expected to be small E01-020: pm = 0.5 GeV/c I = 90mA

  19. Expected Final Yield Applied Cuts: -0.05≤qe≤0.05 -0.025≤fe≤0.025 -0.08≤Dp/p≤0.04 -0.06≤qp≤0.06 -0.035≤fp≤0.035 -0.1≤Dp/p≤0.1 1.3≤xBj≤1.4

  20. Expected Results

  21. Cross Sections

  22. What If ? Why would other models fail ? These would indicate new phenomena

  23. Beam Time Request Time in hours

  24. Summary • Measure cross sections for pm up to 1 GeV/c • Errors are statistics dominated: 7% - 20% • Estimated systematic error ≈ 5 % • Probe NN interaction in new kinematic regions • Exploit cancellation of interference and rescattering terms (FSI small) • Very good theoretical support available • JLAB uniquely suited for high pm study • request 21 days of beam time

  25. FSI as Rescattering

  26. Angular Distribution lower Q2

  27. Estimated Counts per Setting Estimate using SIMC and PWIA Dpm=40 MeV/c, no acceptance cut

  28. TAP Reports • H(e,e’p) for calibrationpurposes • rate at qe=11.68o 125Hz for 80mA • 20 cm target length: very little effect on rates • HMS defines target length acceptance • HMS at rel. large angles • cuts defined by coincidence acceptance • large Dp/p acceptance of SHMS does not match HMS momentum acceptance

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