Abstract: A method for using secondary radiation scattering to evaluate the thickness of materials. The thickness of a first material adjacent to a second material may be evaluated by bombarding the first material with radiation and measuring the radiation scattered by the second material behind it. The method is particularly useful in evaluating the thickness of hydrocarbon-carrying pipelines.

Abstract: An image scanning apparatus for obtaining radiographic information from a detector system. The apparatus produces a video signal by optical readout of a latent image found in a detector system. The video signal is processed and displayed to provide radiographic information.

Abstract: A method of operating a photodetector system. The method impresses a surface charge on a photon detector by establishing an electric potential across the detector, storing the detector in the dark, disconnecting the source of electric potential, and electrically connecting layers in the detector.

Abstract: An array of optically isolated small area scintillators overlie a duophotoconductive sandwich, which includes interdigitated electrodes. The sandwich structure wound each interdigitated electrode is precharged to act as a separate small area detector. The duophotoconductive sandwich includes a photoconductive layer adjacent the scintillators and a second photoconductive layer which, in cooperation with the interdigitated electrodes, acts as a switch, when activated by a beam capable of generating charge carriers in the photoconductor, thus successively connecting each of the small area detectors to a low noise preamplifier.Two embodiments, an experimental setup and a method of operation are disclosed.