Radiation from a charged particle flying through a dielectric ball
  The radiation from a relativistic charged particle uniformly moving through the centre of a dielectric ball is investigated. Analytical expressions for spectral and spectral-angular distributions of the radiated energy are derived and numerical results for the spectrum of radiation are given. It is shown, that the spectral distribution of Cherenkov radiation generated by the relativistic particle inside a dielectric ball at specified frequencies is strongly influenced by the ballvacuum boundary. 
Svetlana R. Arzumanyan
physics.class-ph cond-mat.other physics.acc-ph