On the influence of crystal structure on the electromagnetic shower development in the lead tungstate crystals

The development of high-energy electromagnetic showers in long oriented lead tungstate crystals, accelerated by the effects induced by the strong field of atomic strings, is simulated for the first time. For that the characteristics of pair production and gamma-radiation by electrons or positrons were first simulated by the direct application of Baier-Katkov formulae in a thin PWO crystal to derive the scaling coefficients of the corresponding Bethe-Heitler cross sections to be incorporated into GEANT4 for the simulation of the electromagnetic shower development in a long crystal. Simulation results demonstrate the significant influence of the crystal structure on the e± and gamma-quanta registration processes in the existing homogeneous electromagnetic calorimeters and gamma-telescopes as well as wide possibilities of improving their performance in future developments.