Polarized angular distributions of parametric x radiation and vacuum-ultraviolet transition radiation from relativistic electrons

We present quantifiable images of the angular distributions (AD's) of parametric x radiation (PXR), and vacuum-ultraviolet transition radiation (vuv TR) from 230 MeV electrons interacting with a silicon crystal. Both AD's are highly polarized. The vuv TR and optical TR data provide measurements of the beam energy and effective divergence angle. Using these quantities and separately known values of the electronic susceptibility {}χ₀{}, we show that the measured PXR AD is in good agreement with the predictions of single crystal theory. Our analysis suggests a method to measure {}χ₀{} using PXR AD's.