Room 307, Gilman Hall, University of California

In this small research laboratory at the University of California at Berkeley, the man-made element Plutonium, was first identified. From that day in February 1941, atomic research continued until ultimately a new source of energy had been developed. Had it not been for the momentous discovery here, neither the atomic explosives used in 1945 to end the War with Japan, nor the subsequent development of nuclear energy reactors would have been possible.

Room 307, Gilman Hall, University of California is located at the University of California, Berkeley in Berkeley, California and was added to the National Register of Historic Places (#66000203) on October 15, 1966.

Although the possibility of extending the periodic table of elements had been considered many times, the hope of extension did not become realistic until 1934, when artificial radioactivity was discovered.

Ninety-two elements were then known, but in 1940, the first of the man-made elements was developed by bombarding uranium with neutrons until it captured a neutron and released an electron, thereby producing a new element, #93, Neptunium, an isotope of Uranium.

A few months, later, five co-workers shared in the discovery of element 94, Plutonium, by the same process. They were: Arthur Wall, Edwin MacMillan, Glenn Seaborg, Emilio Segre, and J.W. Kennedy. By using a cyclotron to bombard uranium oxide with neutrons, they created another isotope, and the one which has been far more important than any other. Plutonium, used in a nuclear fission process, can be and has been used for both power-generation in a nuclear reactor, and as an atomic explosive. Doctors Seaborg and MacMillan later shared a Nobel Prize for their work in this field.