Compton scattered transition radiation from very high energy particles

X-ray transition radiation can be used to measure the Lorentz factor of relativistic particles. At energies approaching gamma = E/mc(2) = 10(5), transition radiation detectors can be optimized by using thick (similar to5-10 mil) foils with large (similar to5-10 mm) spacings. This implies X-ray energies greater than or similar to 100 keV and the use of scintillators as the X-ray detectors. Compton scattering of the X-rays out of the particle beam then becomes an important effect. We discuss the design of very high energy detectors, the use of metal radiator foils rather than the standard plastic foils, inorganic scintillators for detecting Compton scattered transition radiation, and the application to the ACCESS cosmic ray experiment. (C) 2002 Published by Elsevier Science B.V.