Measurements of Transverse Spin Asymmetries in eC and eAl Elastic Scattering at the Qweak Experiment.

Previous measurements of the beam-normal single-spin asymmetry A_n on light nuclei with atomic masses up to carbon agree with the AQ/Z scaling predicted by two-photon exchange calculations. However, the agreement breaks down for the heavy nucleus of lead which has a measured A_n consistent with zero (at 95% C.L.). Measurements at atomic masses between carbon and lead may explain the reasons for the disagreement. The Qweak experiment at Jefferson Lab has made the first precise determination of the weak charge of the proton in elastic scattering of longitudinally polarized electrons from unpolarized protons in a liquid hydrogen target. To correct for the contributions from background processes, we conducted several additional parity-violating and parity-conserving asymmetry measurements at different kinematics, with longitudinal and transverse beam polarization, and on several nuclear targets. I will present new preliminary measurements of the beam-normal single-spin asymmetry in elastic electron scattering from carbon and aluminum nuclei. The aluminum measurement will provide the first data with an atomic mass between the existing data on carbon and lead.