Radiation: Atomic Signals from Silver

Since late last year, the silver-short U.S. has been forced to mint silverless "sandwich" quarters and dimes containing a central layer of copper between two thin slices of copper-nickel alloy. Now another Government agency has suggested a more direct solution: find more silver. To aid prospectors, U.S. Geological Survey scientists have designed and successfully tested a "silver snooper," a device capable of locating silver deposits buried as deep as three feet below the ground. By shooting a stream of neutrons into the earth, the snooper turns the silver temporarily radioactive, causing it literally to signal its presence.

Silver atoms that...