On optical transition radiation of charged particles in SiO2-aerogels

Optical transition radiation (OTR) emitted on a charged particle passing through a stack of transparent plates with the parameters close to SiO2-aerogels is analyzed. At low velocities β (β < 0.2) the OTR intensity is found to be much higher as compared with the radiation in a regular solid transparent radiator of the same thickness. The rise in the intensity is caused by optical parametric Vavilov-Cherenkov radiation, its emission being favoured by the conditions in the above-mentioned stack of plates.