Silver halide emulsion

A silver halide emulsion comprising silver halide grains, wherein the silver halide grains each have a chloride content of not less than 90 mol % and are internally doped with an iridium compound (A), a compound (B) forming a stronger electron trap than said iridium compound (A) and a compound (C) comprising a metal selected from group 8 of the periodical table of elements except for iridium and at least an CN ligand;

• the silver halide grains meeting the following requirement:
• 100<z/Y<10000
• wherein Y represents an average number of molecules of said compound (B) contained per grain and Z represents an average number of molecules of said compound (C) contained per grain.

The silver halide emulsion, wherein said iridium compound (A) is a six-coordinate complex containing six halogen atoms as ligands.

A method for preparing a silver halide emulsion comprising silver halide grains, each having a chloride content of not less than 90 mol % and being internally doped with an iridium compound (A) and a compound (B) forming a stronger electron trap than said iridium compound (A),

• the method comprising forming silver halide grains by adding a silver salt and a halide salt to an aqueous solution containing a dispersing medium, and further comprising adding an iridium compound (A) and adding a compound (B) during forming the silver halide grains, wherein the silver halide grains meeting the following requirement:
• 10<X<1000 and 0<Y≦X
• wherein X represents an average number of molecules of said iridium compound (A) contained per grain and Y represents an average number of molecules of said compound (B) contained per grain.