Ultra-monochromatic far-infrared Cherenkov diffraction radiation in a super-radiant regime

Nowadays, intense electromagnetic (EM) radiation in the far-infrared (FIR) spectral range is an advanced tool for scientific research in biology, chemistry, and material science because many materials leave signatures in the radiation spectrum. Narrow-band spectral lines enable researchers to investigate the matter response in greater detail. The generation of highly monochromatic variable frequency FIR radiation has therefore become a broad area of research. High energy electron beams consisting of a long train of dense bunches of particles provide a super-radiant regime and can generate intense highly monochromatic radiation due to coherent emission in the spectral range from a few GHz to potentially a few THz. We employed novel coherent Cherenkov diffraction radiation (ChDR) as a generation mechanism. This effect occurs when a fast charged particle moves in the vicinity of and parallel to a dielectric interface. Two key features of the ChDR phenomenon are its non-invasive nature and its photon yield being proportional to the length of the radiator. The bunched structure of the very long electron beam produced spectral lines that were observed to have frequencies upto 21 GHz and with a relative bandwidth of 10–4 ~ 10–5. The line bandwidth and intensity are defined by the shape and length of the bunch train. A compact linear accelerator can be utilized to control the resonant wavelength by adjusting the bunch sequence frequency.

Decanaling of high-energy particles from planar channels of crystal. Elastic and inelastic scattering processes

Based on the principles of nonequilibrium statistical thermodynamics, the kinetic theory of de-channeling of high-energy particles from planar channels of a crystal have been deduced. The de-channeling rate coefficient is considered from the point of view of the transition of a fast particle from the directional motion mode to the state of chaotic motion. The corresponding equation have been obtained that takes into account both the coherent nature of the diffraction of a particle beam in a regular single crystal and the inelastic scattering of channeled particles by electrons and phonons. An analytical solution of this equation have been obtained on the class of confluent hypergeometric function using which the de-channeling rate constant Re have been calculated. It have been shown that up to second-order terms in terms of the interaction potential the constant Re is inversely proportional to the relaxation time of the system tph. In calculating tph the polarization of space by a fast charged particle is not taken into account. The temperature and isotopic dependences of the de-channeling rate have been obtained.