基本信息
摘要：A screen which scintillates under the action of alpha-particles or X-ray comprises a carrier of polystyrene or polymethyl methacrylate with particles of a phosphor wholly or partially embedded therein, the screen being prepared by incorporating phosphor particles in a liquid, producing polystyrene or polymethyl methacrylate, in such a manner that a majority of the phosphor particles will be positioned closer to one of the major surfaces of the carrier then to the opposing surface, and solidifying the liquid by polymerization. The liquid can comprise styrene monomer or methyl methacrylate monomer or partially polymerized such materials, a solution or dispersion of polystyrene in styrene monomer or in partially polymerized styrene, or a solution or dispersion of polymethyl methacrylate in methyl methacrylate monomer or in partially polymerized methyl methacrylate. Polymerization can be effected by utilizing heat, U.V. or I.R. irradiation, or pressure. In one example, zinc sulphide is dusted over a temporary flat supporting surface of glass to which it may be bonded lightly by phosphoric acid, and a liquid consisting of partially polymerized methyl methacrylate together with a curing agent such as benzoyl peroxide is poured over the phosphor layer and polymerization completed by exposure under an I.R. lamp. Backing plates of polymethyl methacrylate or glass are attached to the surface of the film so produced by a glue consisting of partially polymerized methyl methacrylate containing a small quantity of benzoin and the glue hardened by exposure to U.V. light. The film is then removed from the glass plate and coated with one or more light reflecting and/or excluding metallic, e.g. aluminium, films by e.g. electrode sputtering, vaporization under reduced pressure or by transfer from a temporary supporting surface. Alternatively, or additionally thin films consisting of a resin with a dissolved dye can be used. In another example, the phosphor is suspended in the monomer of, or partially polymerized, styrene or methyl methacrylate with polymerization agents, and the liquid poured into a flat dish and the phosphor allowed to settle, polymerization being thereafter effected by heat and/or U.V. light. In a further example, the phosphor is dusted over the surface of the liquid monomer of, or partially polymerized, styrene or methyl methacrylate and the liquid polymerized. Organic phosphors may be used.
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