Further developments and applications of radiography and tomography with thermal and cold neutrons

Abstract

In the current study various new experimental methods and computation procedures in the field of neutron radiography and tomography are presented. These methods have a significant technical importance in the non-destructive material investigations. Different techniques for a contrast enhancement, contrast variations and an increase of the image sharpness were developed. In a beam geometry with a high lateral coherency of the neutron waves for the first time phase contrast radiography experiments with polychromatic neutrons were performed and analytically simulated. Therewith very fine structures were visualized which was impossible with the standard absorption radiography technique. By the utilization of a neutron velocity selector radiography and tomography experiments below and above the Bragg cut offs for objects, composed from different materials, were performed and the possibility for a material identification was tested. Using the method of the neutron topography the quality of single crystals was investigated. For some of these experiments Monte Carlo simulations were performed using the powerful MCNP-code. This method was used also for the development of a mobile neutron radiography setup. Some of the achieved developments will be used at the radiography and tomography facilities at the new research reactor FRM II in Munich, Germany.