Americium

(the Americas) Americium was the fourth transuranic element to be discovered; theisotope 241Am was identified by Seaborg, James, Morgan, and Ghiorso late in 1944 at thewartime Metallurgical Laboratory of the University of Chicago as the result of successiveneutron capture reactions by plutonium isotopes in a nuclear reactor. The luster offreshly prepared americium metal is white and more silvery than plutonium or neptuniumprepared in the same manner. It appears to be more malleable than uranium or neptunium andtarnishes slowly in dry air at room temperature. Americium must be handled with great careto avoid personal contamination. The alpha activity from 241Am is about three times thatof radium. When gram quantities of 241Am are handled, the intense gamma activity makesexposure a serious problem. 241Am has been used as a portable source for gammaradiography. It has also been used as a radioactive glass thickness gauge for the flatglass industry and as a source of ionization for smoke detectors.