Interference phenomenon in optical transition radiation and its application to particle beam diagnostics and multiple-scattering measurements

• DOI: 10.1063/1.322092
• Publication Date: 2003-02-14T20:50:24Z
• Authors: L. Wartski; S. Roland; J. Lasalle; M. Bolore; G. Filippi
• Keywords: 03 medical and health sciences; 0302 clinical medicine; 7. Clean energy

The optical transition radiation emitted by electron-irradiated aluminum, silver, gold-coated plates, and self-supported aluminum and Mylar films has been investigated experimentally. The investigation was made with an electron beam incident at 45 °, having a mean intensity of 1 μA, and an energy which was varied from 35 up to 72 MeV (68.5<γ<140.9). The study of the angular distribution and degree of polarization has shown that the high-directivity radiation is emitted around the direction of specular reflection and that the contribution of the optical bremsstrahlung is negligible. When two parallel foils are used, the resulting angular distribution exhibits an oscillating behavior arising from the interference of the fields emitted at both interfaces. This interference phenomenon is strongly related to the so-called formation zone in a vacuum, introduced by Garibyan. The intensity of light integrated in a small aperture at the center of the interference pattern presents a strong γ dependence (of the form γ8) which was exploited in the optimization of the phase adjustment of the electron bunches in the accelerating sections of the machine. In such a device using the interference phenomena in transition radiation, the possibility of measurements of the beam energy with a precision of about 1% has also been shown. On the basis of the visibility of fringes, the angular spread of the electron beam and the mean-square scattering angle in a given material were also estimated.