Design of a High-Energy and High-Resolution detector for X-ray computed tomography

The Nuclear Measurement Laboratory (LMN) at CEA Cadarache in France is developing a high-energy tomograph reaching energies up to 21 MeV with high dose rates. It allows performing tomographies on massive objects (5 tons, 140 cm diameter) with a multimillimetric spatial resolution. For the control of absence of cracks, bubbles or defects in the concrete coating of some CEA waste drums, the laboratory needs a "high-resolution" version of this tomograph. The purpose of this study is to design an imaging detector able to provide a high spatial resolution on large objects with high dose resistance and scanning times of a few hours. To achieve this design, several steps are necessary and will be presented: - A first step consists in characterizing the current detection elements of the tomograph, such as the camera and its lens with experimental measurements. This enables to compare performance of these elements with that available on the market and to consider a replacement. - Then, the scintillator is selected according to experimental measurements on few scintillator types and a state of the art. - Next, the detector configuration is optimized to achieve the higher spatial resolution. Throughout these steps, we present the design of a high-resolution detector with a spatial resolution around 300 mu m for a 10%contrast.