Discovery of americium

Americium was synthesised in 1944 at the Metallurgical Laboratory of the University of Chicago, a part of the Manhattan Project, by Glenn Seaborg with Ralph James, Leon Morgan and Albert Ghiorso. They produced it by bombarding plutonium with neutrons in a nuclear reactor, and the new element had the atomic number 95. Its existence was kept secret during the war, and Seaborg is said to have revealed it on a children's radio programme in 1945. It was named after the Americas, by analogy with europium, the rare earth element that lies just above it in the periodic table. Americium-241 is the active ingredient in most household smoke detectors, where its alpha particles ionise the air inside a small chamber.

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