Measurement of gamma beams profile by Cherenkov radiation in fibers

Results of γ-beam profile experimental investigations measuring of Cherenkov radiation [1] generated in an optical fiber with 0.6 mm and 5 mm diameter are presented. These experiments were carried out on γ beams of the linac�Philips SL-75� and the betatron, both with 6 MeV energy. In works [2,3] authors have showed feasibility of Cherenkov radiation applying for high energy beam diagnostics. In our work the Cherenkov radiation yield dependence on the fiber orientation with respect to the beam axis was investigated and showed that the maximal light yield corresponds to the angle between fiber and beam axes closed to the Cherenkov angle [1]. Proposed technique for measurements of γ and electron [4] beam profiles is insensitive to low energy part of the bremsstrahlung spectrum and to undesirable background in contrast with well-known technique based on ionization chambers. Using such a technique it is possible to construct compact and noise insensitive device. It is also possible to reach submillimeter spatial resolution.