Amplification of reflected x-ray beams by the mirage effect

By measuring X-ray from a bent Si single crystal, we have observed the amplification of the reflected beams from the surface. The amplification is observed when the incident angle is adjusted to minimize the effective linear absorption coefficient due to the dynamical diffraction effect. When we increase the width of the incident X-rays along the incident azimuth, we observe on increase in reflected beam intensity. The amplification can be explained by the addition of the electric fields of the propagating beams along hyperbolic trajectories in the bent crystal to those of the reflected beams. (author)