A compact tunable x-ray source based on parametric x-ray generation by moderate energy linacs

摘要

Parametric x-radiation can be described asthe diffraction of virtual photons associated withthe electric field of a relativistic charged particlepassing through a crystal. In analogy with Braggreflection of x-rays, these diffracted photonsappear as real photons, with an energy whichsatisfies Bragg's law for the reflecting crystalplanes. We describe the results of experimentsperformed on the Naval Postgraduate School linacwhich were designed to explore the basicproperties of PXR in order to assess its potentialapplication as a compact tunable x-ray source.Experiments using a mosaic graphite radiatorshow that this radiator produced multiple order,narrow bandwidth reflections from 5 - 45 keV.The measured production efficiency is found toexceed that predicted for spectral orders n > 1.We demonstrated the tunability of PXR byrotating the crystal in order to change the Braggangle relative to the incident 90 MeV electronbeam.