New features in cold neutron radiography and tomography: Part I: thinner scintillators and a neutron velocity selector to improve the spatial resolution

The tomography setup developed at the PGA facility of the Swiss spallation source SINQ has provided encouraging results in the field of cold neutron imaging. Performances of the detection system based on a CCD camera and a converter screen have been recently improved using 6LiF/ZnS:Ag scintillators with different thickness. Indeed, reducing the layer of the scintillator improved considerably the spatial resolution while keeping a reasonable efficiency. Furthermore, a neutron velocity selector was temporarily added to the setup to perform radiography and tomography experiments with monochromatic neutron beams. Basic properties of transmitted beams were studied to assess the applicability of this device in neutron imaging. Of interest was the enhancement of the L/D-ratio by selecting neutron beams of short wavelengths. Cold neutron tomography demonstrated to be a useful technique in various spheres of activity, such as aerospatial industry or radioactive waste storage. Various applications of the neutron velocity selector are described in the second part, namely, New features in cold neutron radiography and tomography—Part II: Applied energy-selective neutron radiography and tomography.