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General Information about the Experiment

GEn will run in Hall A from about Feb 28, 2005, to May 09, 2005. Please consider signing up for shifts.

Physics Motivation: Measurement of the Neutron Electric Form Factor GEn  at High Q2

    Knowledge of the neutron electric form factor GEn is essential for the understanding of the structure of the nucleon, and a key ingredient in the analysis of processes involving electromagnetic interactions with complex nuclei. Recent results on the electric form factor of the proton GEp from experiments E93-027 and E99-007 utilizing the recoil polarization technique at JLab, show that the ratio GEp/GMp decreases sharply as Q2 increases. Thus, the electric and magnetic form factors behave in a different manner from values of Q2 of the order of 1 (GeV/c)2 upwards. The same mechanisms that cause such a deviation should also be present in the neutron, but no accurate data exists at these momentum transfers.

     In the GEn 02-013 experiment at JLab's Hall A we intend to measure the neutron electric form factor GEn at high four-momentum transfer values of Q2 = 1.3, 2.4, and 3.4 (GeV/c)2 in double polarized 3He(e, e'n) scattering in quasi-elastic kinematics, by measuring the asymmetry AT of the cross section. The experiment will make use of the polarized 3He target and of the polarized CEBAF beam at moderate beam energies of 1.644, 2.444, and 3.244 GeV. The electrons will be recorded in the BigBite spectrometer whereas the neutrons will be detected in an array of scintillators. Because of the high kinetic energy of the neutrons it is possible to achive a high neutron detection efficiency with an excellent background suppression. During the scheduled beamtime of 768 hours the GEn value can be measured to a statistical accuracy of ΔGEn/GEn= 0.14 for the three proposed values of Q2.

The Collaboration

  The Spokespeople:

    Gordon Cates

    Kathy McCormick

    Bodo Reitz

    Bogdan Wojtsekhowski (Contact Person)

  Thesis Students (except the last one in the list):

    Sergey Abrahamyan (Yerevan, Armenia)

    Brandon Craver (University of Virginia, Va, USA)

    Aidan Kelleher (The College of William and Mary, Va, USA)

    Ameya Kolarkar (University of Kentucky, Ky, USA)

    Jonathan Miller (University of Maryland at College Park, Md, USA)

    Seamus Riordan (Carnegie Mellon University, Pa, USA)

    Jaideep Singh (Non-thesis student, University of Virginia, Va, USA)

  Others in the Collaboration (includes shift-takers; I'll put in the affiliations soon ...):

J.P. Chen, E. Chudakov, C. deJager, P. Degtiarenko, R.J. Feuerbach, J. Gomez, O. Hansen, D. W. Higinbotham, M. Jones, J. LeRose, W. Melnitchouk, R. Michaels, S. Nanda, B. Reitz, A. Saha, B. Wojtsekhowski, S. Wood
Thomas Jefferson National Accelerator Facility, Newport News, VA 23606

B. Anderson, A. T. Katramotou, K. McCormick, G. G. Petratos, J. Watson, Wei-Ming Zhang
Kent State University, Kent, OH 44242

G. Cates, D. Day, A. Deur, R. Lindgren, N. Liyanage, V. Nelyubin, B. E. Norum, O. Rondon, S. Tajima, K. Wang
University of Virginia, Charlottesville, VA 22901

G. Warren
University of Basel, Basel, Switzerland

D. Nikolenko, I. Rachek
Budker Institute, Novosibirsk, Russia

J. Annand, D. Ireland, J. Kellie, K. Livingston, G. Rosner, D. Watts
University of Glasgow, Glasgow, Scotland

P. Markowitz, M. M. Sargsian, L. Coman
Florida International University, Miami, FL 33199

A. Danagoulian, A. Nathan
University of Illinois, Champaign-Urbana, IL, 61801

K. Allada, C. Dutta, W. Korsh, P. Zolnierczuk
University of Kentucky, Lexington, KY 40506

K. G. Fissun
University of Lund, Lund, Sweden

J. M. Udias
Universidad Complutense de Madrid, Madrid, Spain

J. J. Kelly
University of Maryland, College Park, MD 20292

J. Calarco, W. Hersman
University of New Hampshire, Durham, NH 03824

V. Punjabi
Norfolk State University, Norfolk, VA 23504

B. Vlahovic
North Carolina Central University, Durham, NC

R. Niyazov, A. Radyushkin, L. Weinstein
Old Dominion University, Norfolk, Va 23529

M. Strikman
Pennsylvania State University, University Park, PA 16802

P. Stoler
Rensselaer Polytechnic Institute, Troy, NY 12180-3590

R. Gilman, C. Glashausser, X. Jiang, G. Kumbartzki, R. Ransome
Rutgers, The State University of New Jersey, Piscataway, NJ 08854

J. M. Laget, F. Sabatie
CEA Saclay, Gif-sur-Yvette, France

F. Garibaldi, M. Iodice
INFN, Rome, Italy

R. De Leo
INFN, Bari, Italy

J. Lichtenstadt, E. Piasetzky
Tel Aviv University, Israel

S. Choi, A. Lukhanin, Z.-E. Meziani, N. Ploquin, B. Sawatzky, K. Slifer, P. Solvignon
Temple University, Philadelphia, PA 19122

D. Armstrong, T. Averett, M. Finn, C. Perdrisat, B. Moffit, V. Sulkoski, J. Katich, S. Fuchs, K. Grimm
College of Willaim and Mary, Williamsburg, VA 23185

K. Egiyan, A. Ketikyan, A. Shahinyan, H. Voskanyan
Yerevan Physics Institute, Yerevan, Armenia

D. Margaziotis, T. Ngo
California State University, Los Angeles, CA

D. Rohe

Catherine Ferdi

Guido Urciuoli

Lisa Kaufman

Arie Beck, Sharon Beck

Andrew Puckett

Oleksandr Glamazdin

Mahbub Khandaker

Francesco Cusanno

Xiaofeng Zhu

Lubomir Pentchev

Justin Wright

Klaus Grimm

Paul Reimer

Luis Fraile

Simon Sirca

Jose Udias

Frank Wesselmann

Werner Boeglin

Cesar Fernandez

Joaquin Lopez

Milan Potokar

Brian Quinn

Alexandre Camsonne

David Howell

Dan Protopopescu

The Hall A Collaboration

 On leave from SPNPI of Russian Academy of Sciences, Gatchina, Russia.

  Helpers in Hardware:

Coming soon ...

Maintained by John LeRose

Last modified: Wed Feb 8 19:34:56 EST 2006