Recent progress in the development of transition radiation detectors

Transition radiation detectors have been used in several recent cosmic ray experiments for particle identification at energies E/mc2>= 103. In order to optimize the design of such detectors, and to use them for energy measurements over a broad energy range, it is necessary to study the details of the transition radiation process. We therefore present experimental results which test the theoretical predictions more precisely and at higher energies than in previous experiments. We have studied the dependence of the interference pattern in the frequency spectrum on the radiator dimensions. Furthermore, we have measured the total transition radiation yield generated by electrons in various radiators over a very wide energy range, from 5 GeV to 300 GeV. We review the significance of the individual experimental parameters in the desing of transition radiation detectors, and discuss the characteristics of transition radiation detectors capable of measuring particle energies over the range 300 >=E/mc2<=107 5. (author)