EXPERIMENTAL-DETERMINATION OF THE LINEWIDTH OF PARAMETRIC X-RAY-RADIATION AT ELECTRON ENERGIES BELOW 10 MEV

The linewidth of parametric X-ray radiation has been determined experi mentally applying an absorption technique. Using a copper foil of 27.7 mu m thickness and tuning the energy of the PXR peak across the K-abs orption edge of copper by tilting a 55 mu m thick diamond crystal, the variance of the PXR line at 8.98 keV photon energy was found to be si gma = 48 eV. The diamond crystal has been bombarded with electrons of 6.8 MeV kinetic energy delivered by the superconducting linear acceler ator S-DALINAC at Darmstadt. The experimental yield of the intensity a mounts to N = 0.91 X 10(-5) photons/(electron sr). From the measured v ariance the spectral density in the peak is deduced to be J = 0.95 X 1 0(-7) photons/(electron sr eV).