Design and optimization of a CCD-neutron radiography detector

Radiography is a method to visualize the inner structure of macroscopic samples. It is based on the principle of the attenuation of radiation passing through matter, depending on the sample material and geometry. Besides the well-known radiographic examinations with X-rays and γ-rays, neutron radiography provides an important endorsement to radiographic examinations in the field of non-destructive testing (NDT), as contrary to X-rays, neutrons are attenuated by some light materials, as hydrogen, boron and lithium but penetrate many heavy materials. Neutrons are even able to distinguish between different isotopes and besides, neutron radiography is an important tool for the investigation of radioactive materials. One of the key components of a radiography facility is the detector. Usually, it is a two-dimensional, integrating imaging device. For neutron radiography applications requiring high quantitative precision as well as for neutron tomography investigations, a CCD-camera-based neutron radiography detector has been developed. It consists of a neutron sensitive scintillator screen, a nitrogen-cooled slow-scan CCD-camera and a mirror to reflect the light emitted by the scintillator to the CCD-camera. The whole assembly is placed in a light–tight enclosure. This paper presents the basic principle of this detector system, the strategy for the selection of the individual detector components, comparisons of the influence of the use of different components on the properties of the whole imaging device and results of the first test measurements.