The present invention pertains to a method and apparatus for generating a beam of charged particles, accelerating the charged particles toward a first side of a layer of X-ray target material configured to emit Bremsstrahlung radiation through a second side, receiving the Bremsstrahlung radiation on a first face of an additional layer of a different X-ray target material configured to emit characteristic fluorescence X-rays with energy above 20 keV through a second face, wherein the additional layer of X-ray target material is located within 3 mm of the second side of the first layer of material. The first X-ray target material can have an atomic number greater than 21.
