English: Photograph shows the 60-inch cyclotron at the University of California Lawrence Radiation Laboratory, Berkeley, in August, 1939. The metal frame at left is the machine's huge electromagnet. The flat vacuum chamber in which the particles are accelerated is located in the narrow space between the magnet's 60 inch (152 centimeter, 5 foot) pole pieces. The beamline which analyses the particles resulting from the collisions is at right.

The machine was the most powerful particle accelerator in the world at the time. It had started operating early in the year. During the period of the photograph Dr. Edwin M. McMillan was doing the work which led to the discovery of neptunium (element 93) a year later. The instrument was used later by Dr. Glenn T. Seaborg and his colleagues for the discovery of element 94 (plutonium) early in 1941. Subsequently, other transuranium elements were discovered with the machine, as well as many radioisotopes, including carbon-14. For their work, Drs. Seaborg and McMillan shared the Nobel Prize in 1951. The machine was used for the "long bombardments" which produced the first weighable and visible quantities of plutonium, which was used at Chicago by Seaborg and his colleagues to work out the method for separating plutonium on an industrial scale at the Hanford, Washington, plutonium pro...