• A.G. Shkvarunets, R.B. Fiorito
  UMD, College Park, Maryland
• M.E. Conde, W. Gai, J.G. Power
  ANL, Argonne

We have used an optical diffraction-transition radiation interferometer (ODTRI) in a transmission mode to measure the divergence of the low energy 8 MeV ANL-AWA electron beam. The interferometer employs a metallic micromesh first foil, which is used to overcome the inherent limitation due to scattering in the solid first foil of a conventional OTR interferometer, and an optically transparent dielectric foil. The interferences of forward directed ODR from the mesh and radiation from the dielectric foil is observed in transmission. This geometry allows a small gap between the foils (0.9 mm), which is required to observe fringes from two foils at low beam energies. The measured beam divergence is in a good agreement with that obtained using the standard pepper pot technique and simulation code calculations. ODTRI measurements indicate that a single Gaussian distribution is insufficient to describe the angular distribution of the measured beam and that a second Gaussian beam faction or halo beam component is required to fit the data.