M. Liang

Extraction of the neutron magnetic form factor from quasielastic 3He→(e→,e') at Q2=0.1-0.6 (GeV/c)2

We have measured the spin-dependent transverse asymmetry, A_T, in quasi-elastic inclusive electron scattering from polarized 3He with high precision at Q^2 = 0.1 to 0.6 (GeV/c)^2. The neutron magnetic form factor, GMn, was extracted at Q^2 = 0.1 and 0.2 (GeV/c)^2 using a non-relativistic Faddeev calculation that includes both final-state interactions (FSI) and meson-exchange currents (MEC). In addition, GMn was extracted at Q^2 = 0.3 to 0.6 (GeV/c)^2 using a Plane Wave Impulse Approximation calculation. The accuracy of the modeling of FSI and MEC effects was tested and confirmed with a precision measurement of the spin-dependent asymmetry in the breakup threshold region of the 3He(pol)(e(pol),e) reaction. The total relative uncertainty of the extracted GMn data is approximately 3%. Close agreement was found with other recent high-precision GMn data in this Q^2 range.

Polarization transfer in the d(epol,e' ppol)n reaction up to Q^2=1.61 (GeV/c)^2

The recoil proton polarization was measured in the d(epol,e ppol)n reaction in Hall A of the Thomas Jefferson National Accelerator Facility (JLab). The electron kinematics were centered on the quasielastic peak (x{sub Bj} {approx} 1) and included three values of the squared four-momentum transfer, Q{sup 2}=0.43, 1.00 and 1.61 (GeV/c){sup 2}. For Q{sup 2}=0.43 and 1.61 (GeV/c){sup 2}, the missing momentum, p{sub m}, was centered at zero while for Q{sup 2}=1.00 (GeV/c){sup 2} two values of p{sub m} were chosen: 0 and 174 MeV/c. At low p{sub m}, the Q{sup 2} dependence of the longitudinal polarization, P{sub z}, is not well described by a state-of-the-art calculation. Further, at higher p{sub m}, a 3.5 sigma discrepancy was observed in the transverse polarization, P{sub x}. Understanding the origin of these discrepancies is important in order to confidently extract the neutron electric form factor from the analogous d(epol,e npol)p experiment.