Beam Angle Measurement Using Cherenkov Radiation

A simple beam angle monitor utilizing observation of far-field Cherenkov radiation is being developed. The monitor is independent of beam energy as well as position and requires modest camera sensitivity. The angular resolution is determined by beam scattering in a radiator and diffraction from a finite size radiation source. Numerical analysis shows that the angular resolution with a 100-μm thickness fused silica radiator is 800 μrad. The experiment results with 2-mm and 100-μm thickness fused silica agrees with the numerical result qualitatively, but still small error due to misalignment of optics remains. The possibility of non-destructive measurement is also discussed.