Patent ID: 7151266

Claim:
Apparatus for the inspection of cargo containers for nuclear materials comprising: A) one or more arrays of modules, each of said arrays comprising: i) a plurality of grounded, closed conductive tubes having an thin interior coating of B 10 in polyethylene and a central axis and filled with a gas mixture ionizable in the presence of radioactive emissions; ii) a wire having opposing ends suspended along each of the tube axes; iii) a positive dc high voltage source applied to one end of each of the wires; and iv) an amplifier attached to the opposing end of each of said wires through a capacitance to decouple the amplifier from the high voltage; whereby in the presence of a source of X-rays, gamma rays and/or neutrons, such as nuclear material, X-rays, gamma rays and/or neutrons passing through the tubes ionize the gas in the tubes producing electrons or ions by the gas ionization process, said electrons are accelerated toward the wire surface due to the wire's electrical potential, the acceleration of the electrons near the wire's surface being sufficient to ionize more gas and produce an amplification of electrons/ions that creates a surge of current large enough to be detectable by the amplifier.