Photographic Detectors for Neutron Diffraction

Although new boron- and lithium-loaded scintillators yield very fast photographic response for thermal neutrons, it is pointed out that reciprocity-law failure responses will complicate intensity analyses of diffraction pattern films made with these techniques. The magnitude of this effect for a B10-loaded scintillator and type F x-ray film is such that the response is decreased by a factor of at least 4 times at a neutron intensity of 3×103 neutrons/cm2- sec when compared to the response at a neutron intensity 100 times higher. This objection, and that of image nonuniformities, can be eliminated by using slower response metal screens and film detectors. A rhodium-gadolinium screen combination used with a fast x-ray film such as type KK is shown to be a fast technique which will yield diffraction patterns having useful intensity information.