Deuteron Electro-Disintegration at Very High Missing Momenta
Download
1 / 28

presented by Werner Boeglin Florida International University Miami - PowerPoint PPT Presentation


  • 72 Views
  • Uploaded on

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

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'presented by Werner Boeglin Florida International University Miami' - nitza


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Deuteron Electro-Disintegration at Very High Missing MomentaPR10-003Hall C Collaboration Experiment

presented by

Werner Boeglin

Florida International University

Miami


Why the deuteron
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)


Challenges
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 !


Aim of experiment
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


From proposal PR07-006

unexplored

1 GeV/c


D e e p reaction mechanisms
D(e,e’p) Reaction Mechanisms

reduced at certainkinematics ?

expected to be small at large Q2

supressed for x>1


Experiments at low er q 2
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.


Eikonal approximation successfully describes d e e p n at high q 2
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)


Calculations compared to experiment
Calculations Compared to Experiment high Q

Data: Egyian et al. (CLAS) PRL 98 (2007)

pm = 250 ± 50 MeV/c

pm = 500 ± 100 MeV/c

Calculation. Sargsian


Momentum dependence from clas
Momentum Dependence from CLAS high Q

cross sections averagedover CLAS acceptance !


Selection of kinematics
Selection of Kinematics high Q

minimize FSI

pm = 500 MeV/c

pm = 400 MeV/c

pm = 200 MeV/c

pm bin width : ± 20 MeV/c


Angular distributions up to p m 1gev c
Angular Distributions up to p high Qm = 1GeV/c

FSI depend weakly on pm

Calculation: M.Sargsian


Fsi reduction
FSI Reduction high Q

  • b determined by nucleon size

  • cancellation due to imaginary rescattering amplitude

  • valid only for high energy (GEA)


Fsi contribution estimates
FSI contribution estimates high Q

M.Sargsian (GEA)


Measurements in hall c
Measurements in Hall C high Q

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


Kinematic configurations high Q

direct reactionproton is hit

indirect reactionneutron is hit

pn>1.9 GeV/cstrongly suppressed


Estimated counts per setting
Estimated Counts per Setting high Q

Estimate using SIMC and PWIA

Dpm=40 MeV/c, cut on acceptance > 20%


Accidentals expected to be small high Q

E01-020: pm = 0.5 GeV/c I = 90mA


Expected final yield
Expected Final Yield high Q

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




What if
What If ? high Q

Why would other models fail ?

These would indicate new phenomena


Beam time request
Beam Time Request high Q

Time in hours


Summary
Summary high Q

  • 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




Estimated counts per setting1
Estimated Counts per Setting high Q

Estimate using SIMC and PWIA

Dpm=40 MeV/c, no acceptance cut


Tap reports
TAP Reports high Q

  • 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


ad