Abstract: A method for reducing the amount of shielding used in radiation sources, as well as, an improved radiation source (e.g., an x-ray producing device), are provided. The inventive method involves placement of a radiation producing target at the end of a vacuum drift tube and closer to and substantially in the center of a shield for blocking radiation emitted from the radiation producing target.

Abstract: A multiple energy x-ray source capable of rapidly generating and delivering x-rays in the form of successive pulses that alternate between at least two different energy levels, as well as a multiple energy x-ray inspection apparatus for inspecting moving objects that employs such a multiple energy x-ray source, are provided. The inventive x-ray source facilitates the use of differential absorption characteristics as a means for distinguishing materials contained within objects during a moving inspection.