To find the radiated energy, we consider electric field as a function of frequency at some perpendicular distance from the particle trajectory, say, at ( 0 , b , 0 ) , where b is the impact parameter. It is given by the inverse Fourier transform: E → → ( ω ω ) = 1 ( 2 π π ) 3 / 2 ∫ ∫ d 3 k E → → ( k → → , ω ω ) e i b k 2