The efficient identification of relativistic particles by transition radiation
A system of transition-radiation detectors has been constructed and exposed to beams of electrons and pions in the energy range 3-15 GeV at SLAC. Transition radiation was generated in a variety of stacks of mylar foils (radiators), and background tests have been performed with solid targets replacing the radiators. The radiation intensity was detected with 7 multiwire proportional chambers and with high-Z scintillators [Ba(Pb)SO4, CaWO4]. To obtain a high X-ray conversion efficiency, the proportional chambers had a thickness of 4.5 cm and were filled with xenon-CO2 or krypton-CO2 mixtures. The transition-radition yield has been measured, and its dependence on the particle energy and on the radiator configuration has been investigated. While the raw data demonstrate a good separation between electron- and pion-induced signals, a more detailed analysis of the data has been performed and will be discussed. The results of this analysis show that a very efficient identification of individual particles is possible. Typically, a detection efficiency for electrons above 90%, combined with a pion-electron discrimination ratio of 10-3, has been achieved. Some conclusions with respect to the design of a practical detector for relativistic particles will be drawn. © 1974.