Transition radiation detectors

Abstract

The rearrangement of the electromagnetic field of a charged particle at a transition between media with different electric permittivity leads to the emission of electromagnetic radiation, so-called transition radiation. The chapter begins with the description of the characteristics of the radiation at a boundary, such as angular distribution, energy spectrum, dependence on the Lorentz factor γ‎ and photon yield. Then it is shown that a sufficient photon yield can only be achieved with a large number of transitions which is usually accomplished with stacks of thin foils. The interference phenomena and their dependence on the coherence conditions, parametrised by the ‘formation length’ are explained in detail. The explanation includes also threshold and saturation effects on the measurement of the Lorentz factor γ‎. Finally, typical transition radiation detectors are presented.