  In this paper we simulate the emission by charged particles in complex
structures with help of Geant4. We take into account Cherenkov radiation,
transition radiation, bremsstrahlung, pair production and other accompanying
processes. As an application we investigate the full size electromagnetic
calorimeter for the muon g-2 experiment at Fermilab. A calorimeter module (24
are expected in the experiment) consists of a Delrin front panel for
installation of the laser calibration system, 54 PbF2 Cherenkov crystals
wrapped by the black Millipore paper, and silicon photo-multiplier sensors. We
report here on a simulation of radiation from positrons passing through the
calorimeter system. We carry out the simulation using Geant4 toolkit, which
provides a complete set of tools for all areas of detector simulation:
geometry, tracking, detector response, run, event and track management, and
visualization. We consider Cherenkov photons expansion when a positron moves
down through the calorimeter at the arbitrary angle of incidence. Both spectral
and angular distributions of Cherenkov optical photons in different parts of
the calorimeter system have been evaluated as well as the transition radiation
and pre-shower distributions from the panel and from the Al vacuum chamber of
the storage ring. (The paper is in progress).
