Comment to the paper "Radiation induced by relativistic electrons propagating through random layered stacks: Numerical simulation results" by A.A.Varfolomeev and et al NIM B 256,705 (2007)

We show that the numerical code used in the above mentioned paper does not take into account the multiple scattering effects of electromagnetic field properly and is therefore incorrect.Comment: 2pages,submitted to NIM

Resonant Diffusive Radiation in Random Multilayered Systems

We have theoretically shown that the yield of diffuse radiation generated by relativistic electrons passing random multilayered systems can be increased when a resonant condition is met. Resonant condition can be satisfied for the wavelength region representing visible light as well as soft X-rays. The intensity of diffusive soft X-rays for specific multilayered systems consisting of two components is compared with the intensity of Cherenkov radiation. For radiation at photon energy of $99.4eV$, the intensity of Resonant Diffusive Radiation (RDR) generated by $5MeV$ electrons passing a $Be/Si$ multilayer exceeds the intensity of Cherenkov radiation by a factor of $\approx 60$ for electrons with the same energy passing a $Si$ foil. For a photon energy of $453eV$ and $13MeV$ electrons passing $Be/Ti$ multilayer generate RDR exceeding Cherenkov radiation generated by electrons passing a $Ti$ foils by a factor $\approx 130$.Comment: Talk presented at the RC2005, Frascati, Ital

Smith-Purcell Radiation from Rough Surfaces

Radiation of a charged particle moving parallel to a inhomogeneous surface is considered. Within a single formalism periodic and random gratings are examined. For the periodically inhomogeneous surface we derive new expressions for the dispersion relation and the spectral-angular intensity. In particular, for a given observation direction two wavelengths are emitted instead of one wavelength of the standard Smith-Purcell effect. For a rough surface we show that the main contribution to the radiation intensity is given by surface polaritons induced on the interface between two media. These polaritons are multiply scattered on the roughness of surface and convert into real photons. The spectral-angular intensity is calculated and its dependence on different parameters is revealed.Comment: 6 pages, 2 figures, submitted to Phys. Rev. ST Accel. Beam