Phosphors

Abstract

Abstract A scintillation luminescent material comprises a transparent, optically integral, crystalline calcium iodide activated by tin, in the range 10 to 400 p.p.m. by weight. The crystal may be prepared by zone cooling a dried, activated, material, and emits green light, 3,500-6,000 <\>rA, upon gamma-ray excitation (e.g. Co60). The phosphor, which is deliquescent, may be mounted in a sealed metal case, with a glass or quartz window, or for radioscopic purposes a mosaic of crystals (e.g. 0.003 inch thick) may be mounted, side-by-side, the crystals being optically isolated by light-reflective partitions, and the assembly having a metal case and a transparent, e.g. epoxy resin, window. Other scintillator materials referred to are thalliumactivated sodium, calcium and caesium iodides and thallium-activated potassium and caesium bromides, europium-activated calcium iodide, and unactivated calcium iodide. The scintillator may be optically coupled to a photo-multiplier window, or mounted adjacent a photographic film. The phosphor has a decay time of 0.5 microseconds, or less. The phosphor is transparent down to 3800 <\>rA, but is fluorescent at wavelengths up to about 3650 <\>rA, and is useful as a scintillator for energies as low as 33 Kev.

Inventors

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