Today in History - June 8, 1940 - The discovery of element 93, neptunium (symbol Np), a decay product of uranium-239, was announced by Edwin M. McMillan and Philip H. Abelson working at the University of California at Berkeley. Neptunium was named after the planet Neptune and, at the time, was the first element heavier than uranium. Such elements with stable isotopes are called transuranium elements. McMillan was awarded a share of the Nobel Prize for Chemistry in 1951 for the discovery of Neptunium. McMillan was a member of the Radiation Laboratory under Professor E.O. Lawrence with research on nuclear reactions and their products, and the design and construction of cyclotrons and other equipment. He succeeded Lawrence as director of what is now the Lawrence Berkeley National Laboratory in 1958. McMillan was also a member of the Faculty in the Department of Physics at Berkely from 1935 till his retirement in 1974. Today, the Lawrence Berkeley National Laboratory (LBNL), named after Ernest Lawrence, has taken the lead in a diverse range of projects in particle physics and energy, such as environmental energy technologies.

See the Engineering Pathway’s educational resources on radiactive elements, particle physics and the cyclotron or visit the Nuclear Engineering Education or the Chemical Engineering Education community sites for more information.