X-ray narrow-line transition radiation source based on low-energy electron beams traversing a multilayer nanostructure.

Abstract

X-ray transition radiation can be generated by low-energy electrons traversing a periodic multilayered solid-state nanostructure. In this paper, we investigate how the photoabsorption and electron scattering losses affect the maximal power of that radiation, the required electron energy, and the optimal total length of such a structure. We show that a combination of materials with high and low atomic numbers can produce an intense x-ray radiation with very narrow spectral peaks at the atomic inner-shell absorption edges of the materials, due to resonant anomalous dispersion of refractive index. We find that the photoabsorption and electron scattering result in only moderate increase of required electron energy as compared with the ideal lossless case. The photoabsorption also puts a certain ``ceiling'' on the required electron energy. We demonstrate the feasibility of an inexpensive x-ray source with mega- (or submega-) eV electrons that can generate narrow-line x-ray radiation. Its brightness can be high enough to compete with synchrotron radiation for a number of applications.