McMillan, Edwin Mattison (1907-1991), an American nuclear physicist, discovered the element neptunium. He made the discovery jointly with his colleague Philip Abelson in 1940. The new element was the first discovered of the transuranium elements, elements that follow uranium on the periodic table (see Transuranium element ). McMillan shared the 1951 Nobel Prize for chemistry with Glenn T. Seaborg for their discovery of the transuranium elements (see Seaborg, Glenn Theodore ). McMillan and Seaborg were part of a team at the University of California at Berkeley that discovered the elements plutonium, americium, curium, berkelium, and californium.
In 1940, McMillan and Abelson synthesized a radioactive element that they called neptunium, after the planet Neptune. This discovery heralded a new era in atomic research. The following year, McMillan, Seaborg, and others produced a form of plutonium called Pu-238 by bombarding uranium-238 with deuterons, the nuclei in atoms of deuterium, an isotope of hydrogen. During the rest of World War II (1939-1945), McMillan worked on the development of radar, sonar, and the atomic bomb.
McMillan also found a way to improve the cyclotron, a machine that accelerates atomic particles, so that it could handle heavier particles. He called this new type of particle accelerator a synchro-cyclotron. See Particle accelerator .
McMillan was born on Sept. 18, 1907, in Redondo Beach, California. He studied at the California Institute of Technology and at Princeton University in New Jersey. He taught at the University of California at Berkeley. From 1954 to 1958, McMillan served on the General Advisory Committee to the U.S. Atomic Energy Commission, the government agency that directed the development and use of nuclear energy. From 1958 to 1973, he was director of the Lawrence Radiation Laboratory (now the Lawrence Berkeley National Laboratory) at the University of California at Berkeley. McMillan died on Sept. 7, 1991.
