Physicists Milton Livingston (left) and Ernest Lawrence in front of a 27-inch cyclotron at Berkeley in 1934
Lawrence's 60-inch cyclotron at Berkeley in 1939 was the most powerful accelerator in the world at the time. Glenn T. Seaborg and Edwin M. McMillan used it to discover plutonium, neptunium, etc., for which they received the 1951 Nobel Prize in chemistry
The cyclotron was the first non-linear particle accelerator. From 1929 onwards, using home-made parts, Ernest Lawrence used small electrical pulses to accelerate particles in circles. Eventually his improvements led to him being awarded the Nobel Prize in 1939.
Lawrence’s cyclotron accelerated charged atomic or subatomic particles by using a constant magnetic field and changing electrical field to create a spiraling path of particles that started at the center of the spiral. After spiraling many times in an evacuated chamber, the high-energy particles could finally smash into atoms and the results could be studied using a detector. One advantage of the cyclotron over prior methods was its relatively compact size that could be used to achieve high energies.
Lawrence’s first cyclotron was only a few inches in diameter, but by 1939, at the University of California, Berkeley, he was planning the largest and most expensive instrument thus far created to study the atom. The nature of the atomic nucleus was still mysterious, and this cyclotron, requiring electric current sufficient to light the city of Berkeley, would allow the probing of this inner realm after the high-energy particles collided with nuclei and caused nuclear reactions. Cyclotrons were used to produce radioactive materials and for the production of tracers used in medicine. The Berkeley cyclotron created technetium, the first known artificially generated element.
The cyclotron was also important in that it launched the modern era of high-energy physics and the use of huge, costly machines that required many people and large areas to operate. One such machine was the synchrotron, a circular accelerator developed later, seen for the first time at the General Electric Company in 1947. This led to modern accelerators such as the LHC.