Transition radiation detectors for energy measurements at high Lorentz factors

The characteristic dependence of the intensity of transition radiation (TR) on the Lorentz factor g 1⁄4 E=mc of a primary particle is key to a number of practical applications. In particular, one may use TR detectors for energy measurements of heavy cosmic-ray nuclei in a region where alternate techniques are difficult to apply. However, a serious constraint can be the saturation of the TR yield at high g-values. We investigate how the onset of saturation can be pushed to as high a Lorentz factor as possible. We then describe the results of test measurements at CERN, which demonstrate the possibility of practical configurations for measurements over the Lorentz factor range of a few hundred to about 10: r 2004 Elsevier B.V. All rights reserved. PACS: 29.40.Cs; 95.55.Vj