Edwin Mattison McMillan was a pioneering American nuclear physicist whose groundbreaking work fundamentally transformed the field of nuclear science. Born in Redondo Beach, California in 1907, he earned his B.Sc. and M.Sc. from the California Institute of Technology before completing his Ph.D. at Princeton University in 1932. McMillan joined the Berkeley Radiation Laboratory under Ernest Lawrence in 1933, where he would spend the majority of his career and eventually become Director of the Lawrence Radiation Laboratory from 1958 to 1973. His early work focused on nuclear reactions and improvements to the cyclotron, establishing him as a leading experimental physicist during a transformative period in atomic research.
McMillan's most significant scientific contribution was the discovery of element 93, neptunium, the first transuranic element ever identified, which he isolated in 1940 with Philip H. Abelson. This groundbreaking work paved the way for the discovery of plutonium and the subsequent development of nuclear energy and weapons. During World War II, he contributed to the Manhattan Project, working on radar and sonar technology before moving to Los Alamos to help develop the atomic bomb. In 1945, McMillan conceived the revolutionary principle of phase stability, which enabled the development of the synchrotron and synchro-cyclotron, particle accelerators that extended the energy of artificially accelerated particles into the hundreds of MeV range and made possible numerous fundamental advances in nuclear physics.
McMillan's enduring legacy in nuclear physics was recognized with the Nobel Prize in Chemistry in 1951, which he shared with Glenn T. Seaborg for their discoveries of transuranium elements. His leadership at the Lawrence Radiation Laboratory established it as a world-leading center for nuclear research, where he mentored generations of physicists and oversaw numerous significant scientific advances. Beyond his Nobel-winning work, McMillan's development of the synchrotron principle revolutionized particle physics research, enabling the exploration of subatomic matter at unprecedented energy levels. Although he passed away in 1991, McMillan's discoveries continue to influence nuclear physics, energy research, and our understanding of the fundamental structure of matter, with his principles of particle acceleration remaining foundational to modern high-energy physics experiments worldwide.
