Exposure of silver halide emulsions during formation

Claim 1

In the process of producing a photographic silver halide gelatin emulsion having grains of emulsion containing in their interior, sub-latent image nuclei for providing sensitivity upon exposure to light, the steps of, first, mixing components including an aqueous solution of a silver salt and an aqueous solution of an alkali metal halide in proportion which forms a precipitate emulsion of a silver halide in aqueous solution in a protective colloid and during the formation of said emulsion exposing the emulsion to ionizing radiation emanating from a source of said radiation located at a distance from the emulsion to produce an emulsion having sub-latent nuclei in the silver halide grains and which upon development without further exposure with a developer of the following compositions: p-methylaminophenol--1 g hydroquinone--3 g sodium sulphite--13 g sodium carbonate--26 g potassium bromide--1 g made up with water to 1000 ml at a devleopment temperature of 20° C. and a development time of 5 minutes, yields a quantity of not more than 20% of reduced silver from the silver halide emulsion of said precipitate emulsion, and second, continuing mixture of said components of a silver salt and aqueous solution of an alkali metal halide in proportion which forms the precipitate of silver halide in aqueous solution, in the absence of radiation to produce silver halide grains having an outer phase lacking nuclei, the grains in their final size containing not more than 98% by volume in the portion containing the nuclei.