Transition Radiation and Its Application to the Detection of Super-High Energy Particles

When a charged particle moving with uniform velocity v crosses the boundary between any two media with different dielectric constants, it will emit electromagnetic radiation, called transition radiation. The emitted frequency spectrum of the transition radiation covers from the optical spectrum up into the x-ray spectrum, the extent of which depends on the Lorentz factor, γ (= l/√ 1 - ß2) of the moving particle. Theory predicts 1) that the intensity of the transition radiation emitted in the optical region is proportional to log γ and 2) that the intensity of the x-ray radiation is linearly proportional to γ. Experimental verification of both these theoretical predictions will be presented and possible application of the transition radiation for the measurement of the γ of super-high energy particles will be discussed.