Biography of Ernest Lawrence, Inventor of the Cyclotron

Physicist Ernest O. Lawrence Behind Cyclotron Panel
Ernest Lawrence behind cyclotron panel. Corbis via Getty Images / Getty Images

Ernest Lawrence (August 8, 1901–August 27, 1958) was an American physicist who invented the cyclotron, a device used to accelerate charged particles in a spiral pattern with the help of a magnetic field. The cyclotron and its successors have been integral to the field of high-energy physics. Lawrence received the 1939 Nobel Prize in Physics for this invention.

Lawrence also played an essential role in the Manhattan Project, procuring much of the uranium isotope used in the atomic bomb launched on Hiroshima, Japan. In addition, he was notable for advocating government sponsorship of large research programs, or "Big Science."

Fast Facts: Ernest Lawrence

  • Occupation: Physicist
  • Known For: Winner of the 1939 Nobel Prize in Physics for the invention of the cyclotron; worked on the Manhattan Project
  • Born: August 8, 1901 in Canton, South Dakota
  • Died: August 27, 1958 in Palo Alto, California
  • Parents: Carl and Gunda Lawrence
  • Education: University of South Dakota (B.A.), University of Minnesota (M.A.), Yale University (Ph.D.)
  • Spouse: Mary Kimberly (Molly) Blumer
  • Children: Eric, Robert, Barbara, Mary, Margaret, and Susan

Early Life and Education

Ernest Lawrence was the eldest son of Carl and Gunda Lawrence, who were both educators of Norwegian ancestry. He grew up around people who went on to become successful scientists: his younger brother John collaborated with him on the medical applications of the cyclotron, and his childhood best friend Merle Tuve was a pioneering physicist.

Lawrence attended Canton High School, then studied for a year at Saint Olaf College in Minnesota before transferring to the University of South Dakota. There, he earned his bachelor’s degree in chemistry, graduating in 1922. Initially a premed student, Lawrence switched to physics with the encouragement of Lewis Akeley, a dean and a professor of physics and chemistry at the university. As an influential figure in Lawrence’s life, Dean Akeley’s picture would later hang on the wall of Lawrence’s office, a gallery that included notable scientists such as Niels Bohr and Ernest Rutherford.

Lawrence earned his master’s degree in physics from the University of Minnesota in 1923, then a Ph.D. from Yale in 1925. He remained at Yale for three more years, first as a research fellow and later assistant professor, before becoming an associate professor at the University of California, Berkeley in 1928. In 1930, at the age of 29, Lawrence became a "full professor" at Berkeley—the youngest-ever faculty member to hold that title.

Inventing the Cyclotron

Lawrence came up with the idea of the cyclotron after poring over a diagram in a paper written by the Norwegian engineer Rolf Wideroe. Wideroe's paper described a device that could produce high-energy particles by “pushing” them back and forth between two linear electrodes. However, accelerating particles to high enough energies for study would require linear electrodes that were too long to contain within a laboratory. Lawrence realized that a circular, rather than linear, accelerator could employ a similar to accelerate charged particles in a spiral pattern.

Lawrence developed the cyclotron with some of his first graduate students, including Niels Edlefsen and M. Stanley Livingston. Edlefsen helped develop the first proof-of-concept of the cyclotron: a 10-centimeter, circular device made of bronze, wax, and glass.

Subsequent cyclotrons were larger and capable of accelerating particles to higher and higher energies. A cyclotron roughly 50 times bigger than the first was completed in 1946. It required a magnet that weighed 4,000 tons and a building that was about 160 feet in diameter and 100 feet tall.

Manhattan Project

During World War II, Lawrence worked on the Manhattan Project, helping to develop the atomic bomb. The atomic bomb required the “fissionable” isotope of uranium, uranium-235, and needed to be separated from the much more abundant isotope uranium-238. Lawrence proposed that the two could be separated because of their small mass difference, and developed working devices called “calutrons” that could separate the two isotopes electromagnetically.

Lawrence’s calutrons were used to separate out uranium-235, which was then purified by other devices. Most of the uranium-235 in the atomic bomb that destroyed Hiroshima, Japan was obtained using Lawrence’s devices.

Later Life and Death

After World War II, Lawrence campaigned for Big Science: massive government spending on large scientific programs. He was part of the U.S. delegation at the 1958 Geneva Conference, which was an attempt to suspend the testing of atomic bombs. However, Lawrence became ill while at Geneva and returned to Berkeley, where he died one month later on August 27, 1958.

After Lawrence's death, the Lawrence Berkeley National Laboratory and the Lawrence Livermore National Laboratory were named in his honor.


Lawrence’s largest contribution was the development of the cyclotron. With his cyclotron, Lawrence produced an element that did not occur in nature, technetium, as well as radioisotopes. Lawrence also explored the cyclotron’s applications in biomedical research; for example, the cyclotron could produce radioactive isotopes, which could be used to treat cancer or as tracers for studies in metabolism.

The cyclotron design later inspired particle accelerators, such as the synchrotron, which have been used to make significant strides in particle physics. The Large Hadron Collider, which was used to discover the Higgs boson, is a synchrotron.


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