Engineering design of a continuous duty γ-production proton target for the contraband detection system

A continuous duty γ-ray production proton target for use with the AES Contraband Detection System (CDS) has been designed, fabricated, and operated. The active element of the target is a thin film of carbon-13 where production of the interrogating γ-rays occurs via a p-γ reaction. To inhibit production of “off-energy” γ-rays stemming from interactions with substrate material, the carbon is sputtered on a tantalum layer (high Z) which is brazed to the OFE copper target structure. The water cooled target system is designed for continuous operation with a 10 ma, 1.76 MeV proton beam with peak power densities on the order of 39 kW/cm² . To deal with this power density, the target is a disk which rotates at 600 RPM with the beam impingement at a radius of 15 cm. This paper discusses the engineering analysis, the design of the brazed disk assembly, and the design of the rotation mechanism and vacuum vessel