Characterization of beam shape systematics in a recoil sensitive atom interferometer

Recent measurements of the fine structure constant using atom interferometry are in significant disagreement. Thus, there is renewed interest in carefully evaluating systematic errors in these measurements. Deviations in the shape of a laser beam from a perfect Gaussian have been identified as a leading source of uncertainty. In this poster, I will explain our plans for evaluating systematic errors due to beam shape distortion in our experiment. Our experiment, the second generation fine structure constant measurement at UC Berkeley, improves on the previous measurement by having a longer propagation distance for the interferometry beam and by using a wider beam.