X-ray transition radiation from an ultrarelativistic charge passing near the edge of a target or through a thin wire

TR from an ultrarelativistic charged particle is explored in the high frequencies limit ω≫ωp. A plate of infinite length but of finite thickness and width is considered as a target. The distribution of the emitted energy over the angles and frequencies has been obtained. The special cases of semi-infinite target and the wire-like target are investigated. The distinctive features of the oblique incidence case are discussed.