[Cuga] Pizza Seminar - Wednesday, August 19, 2009---a message from Hari Areti

[Rachel Harris]

Using Polarized 3He to Study Ay, Ax, Az and GEn
Elena Long, Kent State University

12 Noon, August 19, 2009
Cebaf Center L102/104

Please RSVP to harris at jab.org by
5PM on Tuesday, Aug 18, 2009.

Abstract:
Experiments E05-102 and E08-005 involved measurements of electron
scattering from polarized ^3 He reactions that have been conducted in
Jefferson Lab's Hall A this past year. E08-005 measured the Target
Single-Spin Asymmetry A_y in the quasi-elastic ^3 He|(e, eâEUR^(TM)n)
reaction.
Plane wave impulse approximation (PWIA) predicts that A_y should
be exactly zero. A previous experiment at Q^2 of 0.2 (GeV/c)^2 , where
Laget and Nagorny predict A_y to be small, showed a large
asymmetry as predicted by Faddeev calculations. The recent experiment
measured this asymmetry at Q^2 of 0.1 (GeV/c)^2 , 0.5 (GeV/c)^2 and
1.0 (GeV/c)^2 . This is the first measurement of A_y at large Q2,
which is another region where A_y is expected to be small. Any non-zero
result is an indication of effects beyond impulse approximation.
During E05-102 double-polarized asymmetries (A_x and A_z ) in the
quasi-elastic ^3 (,eâEUR^(TM)d) reaction were measured. Faddeev
calculations
of these asymmetries by the Bochum/Krakow and Hannover groups
result in distinct descriptions. Comparison of these descriptions will
be compared to the data as a function of missing momentum and will
allow for a better understanding of the polarized ^3 He system.
These measurements have important implications for all neutron
experiments using this target. A measurement of the electric form
factor of the neutron (G_E ^n ) was also taken using the ^3 (,eâEUR^(TM)n)
channel at Q^2 of 0.4 (GeV/c)^2 , 0.5 (GeV/c)^2 and 1.0 (GeV/c)^2 . An
overview of these measurements will be presented.