Abstract: Oxyhalides of lanthanum and/or gadolinium coactivated with thulium and terbium are phosphors found to have the advantages of reduced afterglow and increased ultraviolet emisson. The relative speed of the phosphors is also quite high. These phosphors are used in x-ray image converters generally, and can be used in such devices as x-ray image intensifier tubes, in fluoroscopic screens and in radiographic intensifier screens.

Abstract: Oxybromides of lanthanum and gadolinium activated with bismuth are found to be superior in their conversion efficiency of X-rays to visible light when compared with conventional X-ray phosphors. The incorporation of the ytterbium ion in these phosphor materials produces reduced afterglow when used in X-ray image converter devices such as X-ray image intensifier tubes, fluoroscopic screens, and radiographic screens.

Abstract: Mixed rare earth alkali and alkaline earth sulfates activated with cerium and terbium are used as a phosphor coating system for fluorescent lamps. The phosphor efficiently emits light in the green region and the emission spectrum of the phosphor demonstrates a prominent peak in the 520-560 nm region with minor inflections at other visible wavelengths.

Abstract: Thermoluminescent materials have been found suitable for measuring long term exposures to low level ionizing radiation. Oxyhalides of lanthanum, gadolinium and yttrium, including the oxychlorides and oxybromides are activated with terbium and have been found to be most efficient oxygendominated phosphors having thermoradiant efficiencies with excitation by low level ionizing radiation. Thermoluminescence response increases when the previous materials have hafnium and zirconium additives.

Abstract: An X-ray intensifying screen having reduced radiographic mottle comprising a plurality of layers including a photographic film and two or more phosphor layers, the phosphor layers having increasing luminous efficiency, under X-ray radiation, from the layer nearest the photographic film to the outermost layer from said film. The luminous efficiencies are adjusted to cause about equal film densities, on absorption of about equal X-rays for each phosphor layer. Thus, the total density of the phosphor layers would be about equal to the film density of a single phosphor layer comprising a similar phosphor of homogeneous brightness.