Session K20 - Poster Session.
POSTER session, Sunday afternoon, April 29
Congressional C, Renaissance Hotel
To avoid to some extent the undesirable scattering effect of the first foil in the traditional Optical Transition Radiation Interferometer - OTRI we propose a perforated foil as the first foil of the OTRI. Many holes of reasonable size and spacing can be made in this foil. In this case a substantial fraction of the beam electrons will not be scattered and the fraction of beam electrons passing through the holes will produce Optical Diffraction Radiation - ODR. The total coherent radiation produced will be the superposition of radiation from unscattered electrons ( the ODR from the holes in the first foil - OTR from second foil) and OTR from heavily scattered electrons. By choosing appropriate foil spacing and bandpass of the radiation, interference fringes in the light angular distribution (unscattered beam) are visible above the nonfringed background of light produced by the heavily scattered portion of beam. Such a system is planned to characterize the beam used the University of Maryland Infrared Free Electron LASER ( MIRFEL) experiment. Calculations demonstrate capability of the method to measure initial beam angular spread of order of milliradians for beam energies less than 10 MeV.