| 摘要 |
A process for the preparation of a radiation-sensitive silver halide emulsion comprised of high bromide cubical silver halide grains is described, the process comprising: (a) providing in a stirred reaction vessel a dispersing medium and high bromide silver halide seed grains, the seed grains comprising at least 5 mole % of the final emulsion silver, and (b) precipitating a silver halide shell which comprises at least 5 mole % of the final emulsion silver onto the seed grains by introducing at least a silver salt solution into the dispersing medium at a rate such that the normalized shell molar addition rate, Rs, is above 1.0x10<-3 >min<-2>, Rs satisfying the formula:where Ms is the number of moles of silver halides added to the reaction vessel during the formation of the shell, ts is the run time, in minutes, of the silver salt solution for the formation of the shell, and Mt is total moles of silver halide in the reaction vessel at the end of the precipitation of the shell; wherein the concentration of silver halide grains in the reaction vessel at the end of the precipitation of the shell is at least 0.5 mole/L. The invention provides an improved manufacturing process for the preparation of high bromide silver halide cubical grain emulsion enabling concentrated emulsion batches to be prepared with desired photographic properties. In certain embodiments of the invention, further advantages are enabled in accordance with the discovery that when the exterior portion of high bromide silver halide cubic grains are grown under specific conditions of high molar addition rates, emulsions of enhanced sensitivity, improved contrast and radiographic curve shape may be produced while controlling the minimum fog level.
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