A Precision Measurement of the Transverse Asymmetry AT from Quasi-elastic 3He(e,e') process, and the Neutron Magnetic Form Factor GNM at low Q2

Electromagnetic form factors are fundamental quantities in describing the underlying electromagnetic structure of nucleons. While proton electromagnetic form factors have been determined with good precision, neutron form factors are known poorly, largely due to the lack of free neutron targets. Jefferson Lab Hall A experiment E95-001, a ''precise measurement of the transverse asymmetry AT' from the quasielastic 3He(e, e') process,'' was therefore designed to determine precisely the neutron magnetic form factor, GMn at low momentum transfer values and was successfully completed in Spring 1999. High precision AT'data in the quasi-elastic region at Q2 values of 0.1 to 0.6 (GeV/c)2 were obtained using a high-pressure spin-exchange optically-pumped polarized 3He gas target with an average polarization of 30%, a longitudinally polarized e- beam, and two High Resolution Spectrometers: HRSe and HRSh. HRSe was employed to detect scattered electrons from the quasi-elastic kinematic region, and HRSh was employed as a elastic polarimetry to monitor the product of the beam and target polarizations. The extraction of form factors is usually model-dependent. Significant constraints on theoretical calculations are provided bu additional high precision quasi-elastic asymmetry data at Q2 values of 0.1 and 0.2 (GeV/c)2 in 3He breakup region, where effects of final state interactions (FSI) and meson exchange currents (MEC) are expected to be large [71]. GMn is extracted from a non-relativistic Faddeev calculation which includes both FSI and MEC at Q2 values of 0.1 and 0.2 (GeV/c)2. The uncertainties of GMn at these Q2 values are comparable to those of recent experiments with deuterium targets [58]. At the higher Q2 values from this experiment, GMn is extracted from Plane-Wave Impulsive Approximation (PWIA) calculations with a relatively large theoretical uncertainty of 2-4%. Thus a reliable extraction of GMn from A(prime)T at higher Q 2 values (especially at Q2 values of0.3 and 0.4 (GeV/c)2) requires improved theoretical calculations including FSI, MEC, and relativistic effects. However, those GMn results extracted from PWIA at higher Q2 values from the experiment still show overall a good agreement with the most recent deuterium measurements. The analysis of asymmetries and the extraction of GMn from both the Faddeev calculations and the PWIA calculations are reported in this thesis