Development of a thin film 9.17 MeV gamma ray production target for the contraband detection system

We will describe the development of a thin film /sup 13/C target for generating 9.17 MeV gamma rays via a (p,/spl gamma/) reaction for use in a commercial contraband detection system (CDS) employing nuclear resonance absorption. The target required for this system must consist of a thin /sup 13/C film backed by a high Z proton stopping layer. It must be able to withstand average proton beam powers of 17.5 kW, implanted ion doses greater than 10/sup 19//cm/sup 2/ and peak power densities approaching 50 kW/cm/sup 2/ for extended periods of time. These requirements currently cannot be met by conventional target designs employing C/Au structures. After even short exposure times of several minutes to the proton beam the targets suffer from coating de-lamination and blistering. A new more durable target design has been developed which suffers no such degradation after many hours of beam exposure. The new design consists of a thin /sup 13/C film deposited onto a Ta layer which has been brazed onto a Cu cooling support.