Ultra High Energy Photon Showers in Magnetic Field:. Angular Distribution of Produced Particles.

Ultra high energy (UHE) photons can initiate electromagnetic showers in magnetic field. We analyze the two processes that determine the development of the shower, e⁺e^- pair creation and synchrotron radiation, and derive formulae for the angular distribution of the produced particles. These formulae are necessary to study the three-dimensional development of the shower.